U.S. patent application number 09/827653 was filed with the patent office on 2001-11-15 for nonreducing dielectric ceramic and monolithic ceramic capacitor using the same.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Motoki, Tomoo, Naito, Masahiro, Sano, Harunobu.
Application Number | 20010040784 09/827653 |
Document ID | / |
Family ID | 26589704 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040784 |
Kind Code |
A1 |
Naito, Masahiro ; et
al. |
November 15, 2001 |
Nonreducing dielectric ceramic and monolithic ceramic capacitor
using the same
Abstract
A nonreducing dielectric contains a main-component having a
perovskite crystal phase and satisfying the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn.-
sub.xNi.sub.yHf.sub.z)O.sub.3 and a compound oxide represented by
the formulae (Si, T)O.sub.2--MO--XO and (Si, T)O.sub.2--(Mn,
M')O--Al.sub.2O.sub.3. The ratio of the intensity of the maximum
peak of a crystal phase not of the perovskite crystal phase to the
intensity of the maximum peak assigned to the perovskite crystal
phase appearing at 2.theta.=25 to 35.degree. is about 5% or less in
a CuK.alpha. X-ray diffraction pattern.
Inventors: |
Naito, Masahiro; (Yasu-gun,
JP) ; Motoki, Tomoo; (Izumo-shi, JP) ; Sano,
Harunobu; (Kyoto-shi, JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
26589704 |
Appl. No.: |
09/827653 |
Filed: |
April 6, 2001 |
Current U.S.
Class: |
361/321.2 |
Current CPC
Class: |
H01G 4/1227 20130101;
C04B 35/49 20130101; H01G 4/1245 20130101; H01G 4/1236 20130101;
H01B 3/12 20130101 |
Class at
Publication: |
361/321.2 |
International
Class: |
H01G 004/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2000 |
JP |
2000-106906 |
Mar 15, 2001 |
JP |
2001-074810 |
Claims
What is claimed is:
1. A nonreducing dielectric ceramic comprising; a main-component
having a perovskite crystal phase, the main-component satisfying
the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn-
.sub.xNi.sub.yHf.sub.z)O.sub.3 wherein 0.ltoreq.a<0.5,
0.ltoreq.b<0.5, 0.ltoreq.c<0.05, 0.ltoreq.a+b+c<0.5,
0.98.ltoreq.m<1.03, 0.ltoreq.w<0.6, 0.ltoreq.x<0.05,
0.ltoreq.y<0.05, 0.ltoreq.z<0.3, 0.ltoreq.x+y.ltoreq.0.05,
and 0.ltoreq.w+x+y+z<0.6; and at least one compound oxide
selected from the group consisting of (Si, T)O.sub.2--MO--XO and
(Si, T)O.sub.2--(Mn, M')O--Al.sub.2O.sub.3, wherein T is at least
one of Ti and Zr, MO is at least one of MnO and NiO, XO is at least
one member selected from the group consisting of BaO, SrO, CaO and
MgO, and M' is at least one member selected from the group
consisting of Ni, Ba, Sr, Ca and Mg; wherein the ratio of the
intensity of the maximum peak of the crystal phases other than the
perovskite crystal phase to the intensity of the maximum peak
assigned to the perovskite crystal phase appearing at 2.theta.=25
to 35.degree. in a CuK.alpha. X-ray diffraction pattern is about 5%
or less.
2. A nonreducing dielectric ceramic according to claim 1, wherein
the compound oxide is (Si, T)O.sub.2--MO--XO and is represented by
the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2--.beta.(-
Mn.sub.1-.xi.Ni.sub..xi.)O--.gamma.XO, wherein .alpha., .beta., and
.gamma. are molar percent, 0.ltoreq..mu.<0.5,
0.ltoreq..nu.<0.7, 0.ltoreq..xi..ltoreq.1.0,
0.ltoreq..mu.+.nu..ltoreq.0.7; and wherein the
(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2 content, the
(Mn.sub.1-.xi.Ni.sub..xi.)O content and the XO content in the
compound oxide lie within the region in a ternary diagram
surrounded by points A (.alpha.=25.0, .beta.=75.0, .gamma.=0),
B(.alpha.=100.0, .beta.=0, .gamma.=0), C (.alpha.=20.0, .beta.=0,
.gamma.=80.0), and D (.alpha.=5.0, .beta.=15.0, .gamma.=80.0)
including the lines AB, AD, and DC, and excluding the line BC.
3. A nonreducing dielectric ceramic according to claim 1, wherein
the compound oxide is (Si, T)O.sub.2--(Mn, M')O--Al.sub.2O.sub.3
and is represented by the formula
.alpha.(Si.sub.1-.mu.T.sub..mu.)O.sub.2--.beta-
.(Mn.sub.1-.nu.M'.sub..nu.)O--.gamma.Al.sub.2O.sub.3, wherein
.alpha., .beta., and .gamma. are molar percent,
0.ltoreq..mu.<0.5 and 0.ltoreq..nu.<0.5; and wherein the
(Si.sub.1-.mu.T.sub..mu.)O.sub.2 content, the
(Mn.sub.1-.nu.M'.sub..nu.)O content and the Al.sub.2O.sub.3 content
in the compound oxide lie within the region in a ternary diagram
surrounded by points A (.alpha.=80.0, .beta.=20.0, .gamma.=0),
B(.alpha.=10.0, .beta.=90.0, .gamma.=0), C (.alpha.=10.0,
.beta.=20.0, .gamma.=70.0), D (.alpha.=30.0, .beta.=0,
.gamma.=70.0), and E (.alpha.=80.0, .beta.=0, .gamma.=20.0)
including the lines AE, BC and CD and excluding the lines AB and
ED.
4. A nonreducing dielectric ceramic according to claim 1, wherein
said ratio is about 3% or less; and wherein when the compound oxide
is (Si, T)O.sub.2--MO--XO, it is represented by the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2--.beta.(MN.sub.1-
-.xi.Ni.sub..xi.)O--.gamma.XO, wherein .alpha., .beta., and .gamma.
are molar percent, 0.ltoreq..mu.<0.5, 0.ltoreq..nu.<0.7,
0.ltoreq..xi..ltoreq.1.0, 0.ltoreq..mu.+.nu..ltoreq.0.7, and the
(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2 content, the
Mn.sub.1-.xi.Ni.sub..xi.)O content and the XO content in the
compound oxide lie within the region in a ternary diagram
surrounded by points A (.alpha.=25.0, .beta.=75.0, .gamma.=0),
B(.alpha.=100.0, .beta.=0, .gamma.=0), C (.alpha.=20.0, .beta.=0,
.gamma.=80.0), and D (.alpha.=5.0, .beta.=15.0, .gamma.=80.0)
including the lines AB, AD, and DC, and excluding the line BC; and
wherein when the compound oxide is (Si, T)O.sub.2--(Mn,
M')O--Al.sub.2O.sub.3, it is represented by the formula
.alpha.(Si.sub.1-.mu.T.sub..mu.)O.sub.2--.beta.(Mn.sub.1-.nu.M'.sub..nu.)-
O--.gamma.Al.sub.2O.sub.3, wherein .alpha., .beta., and .gamma. are
molar percent, 0.ltoreq..mu.<0.5 and 0.ltoreq..nu.<0.5, and
the (Si.sub.1-.mu.T.sub..mu.)O.sub.2 content, the
(Mn.sub.1-.nu.M'.sub..nu.)O content and the Al.sub.2O.sub.3 content
in the compound oxide lie within the region in a ternary diagram
surrounded by points A (.alpha.=80.0, .beta.=20.0, .gamma.=0),
B(.alpha.=10.0, .beta.=90.0, .gamma.=0), C (.alpha.=10.0,
.beta.=20.0, .gamma.=70.0), D (.alpha.=30.0, .beta.=0,
.gamma.=70.0), and E (.alpha.=80.0, .beta.=0, .gamma.=20.0)
including the lines AE, BC and CD and excluding the lines AB and
ED.
5. A monolithic ceramic capacitor comprising: a plurality of
dielectric ceramic layers; a pair of internal electrodes, each of
which is between a different pair of the plurality of dielectric
ceramic layers; and a pair of external electrodes, each of which is
electrically connected to a different one of the pair of internal
electrodes, wherein each of the plurality of dielectric ceramic
layers comprises a nonreducing dielectric ceramic in accordance
with of claim 4 and the internal electrodes comprise a base
metal.
6. A monolithic ceramic capacitor according to claim 5, further
comprising a plating layer on each external electrode.
7. A monolithic ceramic capacitor according to claim 6, wherein the
base metal is selected from the group consisting of Ni, a Ni alloy,
Cu and a Cu alloy.
8. A monolithic ceramic capacitor according to claim 5, wherein the
base metal is selected from the group consisting of Ni, a Ni alloy,
Cu and a Cu alloy.
9. A monolithic ceramic capacitor comprising: a plurality of
dielectric ceramic layers; a pair of internal electrodes, each of
which is between a different pair of the plurality of dielectric
ceramic layers; and a pair of external electrodes, each of which is
electrically connected to a different one of the pair of internal
electrodes, wherein each of the plurality of dielectric ceramic
layers comprises a nonreducing dielectric ceramic in accordance
with of claim 3 and the internal electrodes comprise a base
metal.
10. A monolithic ceramic capacitor according to claim 9, further
comprising a plating layer on each external electrode.
11. A monolithic ceramic capacitor according to claim 10, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
12. A monolithic ceramic capacitor according to claim 9, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
13. A monolithic ceramic capacitor comprising: a plurality of
dielectric ceramic layers; a pair of internal electrodes, each of
which is between a different pair of the plurality of dielectric
ceramic layers; and a pair of external electrodes, each of which is
electrically connected to a different one of the pair of internal
electrodes, wherein each of the plurality of dielectric ceramic
layers comprises a nonreducing dielectric ceramic in accordance
with of claim 2 and the internal electrodes comprise a base
metal.
14. A monolithic ceramic capacitor according to claim 13, further
comprising a plating layer on each external electrode.
15. A monolithic ceramic capacitor according to claim 14, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
16. A monolithic ceramic capacitor according to claim 13, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
17. A monolithic ceramic capacitor comprising: a plurality of
dielectric ceramic layers; a pair of internal electrodes, each of
which is between a different pair of the plurality of dielectric
ceramic layers; and a pair of external electrodes, each of which is
electrically connected to a different one of the pair of internal
electrodes, wherein each of the plurality of dielectric ceramic
layers comprises a nonreducing dielectric ceramic in accordance
with of claim 1 and the internal electrodes comprise a base
metal.
18. A monolithic ceramic capacitor according to claim 17, further
comprising a plating layer on each external electrode.
19. A monolithic ceramic capacitor according to claim 18, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
20. A monolithic ceramic capacitor according to claim 17, wherein
the base metal is selected from the group consisting of Ni, a Ni
alloy, Cu and a Cu alloy.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a nonreducing dielectric
ceramic, and a monolithic ceramic capacitor using the same.
[0003] 2. Description of the Related Art
[0004] Japanese Unexamined Patent Application Publication Nos.
60-131708, 63-126117, 5-9073, 5-217426, 10-330163 and 10-335169
disclose (Ca.sub.1-xSr.sub.x).sub.m(Zr.sub.1-yTi.sub.y)O.sub.3-type
dielectric ceramic materials as nonreducing dielectric ceramic
materials which exhibit excellent dielectric characteristics and do
not become semiconductive even when internal electrodes provided
therefor are composed of an inexpensive base metal such as nickel
(Ni), copper (Cu), etc., and baking is performed in a neutral or
reducing atmosphere having low oxygen partial pressure.
[0005] By using these dielectric ceramic materials, dielectric
ceramics which do not become semiconductive even when baking is
performed in a reducing atmosphere can be formed. Moreover, the
production of monolithic ceramic capacitors having internal
electrodes composed of a base metal such as nickel (Ni) or copper
(Cu) has become possible.
[0006] However, in the nonreducing dielectric ceramics disclosed in
the above-described Japanese Unexamined Patent Application
Publication Nos. 60-131708 and 63-126117, raw materials, i.e.,
calcium carbonate (CaCO.sub.3), strontium carbonate (SrCO.sub.3),
titanium dioxide (TiO.sub.2) and zirconium dioxide (ZrO.sub.2) are
calcined at the same time as manganese dioxide (MnO.sub.2), which
is a secondary component, and silicon dioxide (SiO.sub.2), which is
a mineralizer, so as to make a ceramic having a main component
satisfying the formula
(Ca.sub.1-xSr.sub.x).sub.m(Zr.sub.1-yTi.sub.y)O.sub.3. As a
consequence, the resulting calcined material powder has not only
peaks characteristic of a perovskite crystal phase which is the
primary crystal phase, but also peaks indicating crystal phases not
of the perovskite crystal phase. When the dielectric ceramic is
formed by sintering one of these calcined material powders in a
reducing atmosphere, crystal phases not of the
perovskite-structured primary crystal phase (i.e., different
phases) remain in the resulting dielectric. When the thickness of
an element is reduced to manufacture a miniaturized
high-capacitance monolithic ceramic capacitor, the performance
thereof in a high-temperature loading lifetime test is degraded
since these different crystal phases have inferior thermal
resistance.
[0007] Japanese Unexamined Patent Application Publication Nos.
63-126117, 5-9073, 5-217426, and 10-330163 disclose nonreducing
dielectric ceramics containing lithium (Li) or boron (B) in their
additive glasses. Because Li and B readily evaporate at high
temperatures, fluctuations in furnace temperature and unevenness of
the atmosphere result in fluctuation in the amount of Li or B
evaporating and the evaporation time. Thus, the characteristics
such as electrostatic capacitance of the resulting capacitors are
irregular.
[0008] Japanese Unexamined Patent Application Publication No.
10-335169 discloses a nonreducing dielectric ceramic comprising a
main component represented by the formula
[(Ca.sub.xSr.sub.1-x)O].sub.m[(Ti.sub.yZr.sub.- 1-y)O.sub.2],
manganese oxide, aluminum oxide, and a secondary component
represented by the formula
[(Ba.sub.zCa.sub.1-z)O].sub..nu.SiO.sub.2. The nonreducing
dielectric ceramic does not contain components which readily
evaporate during baking. Consequently, the ceramics show greater
reliability in a high-temperature loading lifetime test and exhibit
less irregularity in performance. The nonreducing dielectric
ceramic indeed shows some improvement in insulation-resistance in a
high-temperature loading lifetime test but has a significant
proportion of crystal phases which are not of the perovskite
primary crystal phase. As a result, degradation of
insulation-resistance is observed in a moisture-resistance loading
test.
[0009] Recently, the demand for smaller monolithic ceramic
capacitors having large capacitance has required thin yet highly
reliable dielectric ceramic layers. In order to meet this need, a
highly reliable dielectric ceramic material capable of forming
thinner layers and a small, yet highly reliable, monolithic ceramic
capacitor having large capacitance at high temperatures and high
humidity is desired.
SUMMARY OF THE INVENTION
[0010] Accordingly, it is an object of the present invention to
provide a nonreducing dielectric ceramic including a main component
having a perovskite crystal phase, the main component satisfying
the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn.-
sub.xNi.sub.yHf.sub.z)O.sub.3
[0011] wherein 0.ltoreq.a<0.5, 0.ltoreq.b<0.5,
0.ltoreq.c<0.05, 0.ltoreq.a+b+c<0.5, 0.98.ltoreq.m<1.03,
0.ltoreq.w<0.6, 0.ltoreq.x<0.05, 0.ltoreq.y<0.05,
0.ltoreq.z<0.3, 0.ltoreq.x+y.ltoreq.0.05, and
0.ltoreq.w+x+y+z<0.6 and at least one type of compound oxide
selected from one of the group consisting of (Si, T)O.sub.2--MO--XO
wherein T is at least one element selected from Ti and Zr, MO is at
least one selected from MnO and NiO, and XO is at least one
selected from BaO, SrO, CaO and MgO and (Si, T)O.sub.2--(Mn,
M')O--Al.sub.2O.sub.3 wherein T is at least one of Ti and Zr, and
M' is at least one selected from Ni, Ba, Sr, Ca and Mg. The
proportion of the intensity of the maximum peak of a crystal phase
not of the perovskite crystal phase to the intensity of the maximum
peak assigned to the perovskite crystal phase appearing at
2.theta.=25 to 35.degree. is about 5% or less in a CuK.alpha. X-ray
diffraction pattern.
[0012] Preferably, the compound oxide (Si, T)O.sub.2--MO--XO
represented by the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2---
.beta.(Mn.sub.1-.xi.Ni.sub..xi.)O--.gamma.XO, wherein .alpha.,
.beta. and .gamma. are molar percent and XO is at least one of BaO,
SrO, CaO and MgO satisfies the relationships 0.ltoreq..mu.<0.5,
0.ltoreq..nu.<0.7, 0.ltoreq..xi..ltoreq.1.0,
0.ltoreq..mu.+.nu..ltoreq.0.7. The
(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2 content, the
(Mn.sub.1-.xi.Ni.sub..xi.)O content and the XO content in the
compound oxide preferably lie within the region surrounded by
points A (.alpha.=25.0, .beta.=75.0, .gamma.=0), B(.alpha.=100.0,
.beta.=0, .gamma.=0), C (.alpha.=20.0, .beta.=0, .gamma.=80.0), and
D (.alpha.=5.0, .beta.=15.0, .gamma.=80.0) including the lines AB,
AD, and DC, and excluding the line BC is used as the compound oxide
in a ternary diagram.
[0013] Preferably, the compound oxide (Si, T)O.sub.2--(Mn,
M')O--Al.sub.2O.sub.3 represented by the formula
.alpha.(Si.sub.1-.mu.T.s-
ub..mu.)O.sub.2--.beta.(Mn.sub.1-.nu.M.sub..nu.)O--.gamma.Al.sub.2O.sub.3
wherein .alpha., .beta., and .gamma. are molar percent, T is at
least one of Ti and Zr, and M' is at least one of Ni, Ba, Sr, Ca
and Mg, satisfies the relationships 0.ltoreq..mu.<0.5 and
0.ltoreq..nu.<0.5. The (Si.sub.1-.mu.T.sub..mu.)O.sub.2 content,
the (Mn.sub.1-.nu.M.sub..nu.)O content and the Al.sub.2O.sub.3
content in the compound oxide preferably lie within the region
surrounded by points A (.alpha.=80.0, .beta.=20.0, .gamma.=0),
B(.alpha.=10.0, .beta.=90.0, .gamma.=0), C (.alpha.=10.0,
.beta.=20.0, .gamma.=70.0), D (.alpha.=30.0, .beta.=0,
.gamma.=70.0), and E (.alpha.=80.0, .beta.=0, .gamma.=20.0)
including the lines AE, BC and CD and excluding the lines AB and ED
in a ternary diagram.
[0014] The present invention also provides a monolithic ceramic
capacitor including a plurality of dielectric ceramic layers,
internal electrodes provided between the plurality of dielectric
ceramic layers and external electrodes electrically connected to
the internal electrodes. Each of the plurality of dielectric
ceramic layers is formed of the above-described nonreducing
dielectric ceramic in accordance with the present invention. The
internal electrodes are formed of a base metal as the main
component.
[0015] The monolithic ceramic capacitor may be provided with
plating layers on the surfaces of the external electrodes.
[0016] The base metal is preferably one selected from the group
consisting of Ni, a Ni alloy, Cu and a Cu alloy.
[0017] The nonreducing dielectric ceramic in accordance with the
present invention exhibits a high specific resistance of 10.sup.13
.OMEGA..multidot.cm or more and a low dielectric loss of 0.1% or
less. The rate of change in electrostatic capacitance is within
-1000 ppm/.degree.C. The performance thereof in a high-temperature
loading lifetime test and moisture-resistance loading test is
highly reliable. Moreover, irregularities in the characteristics
thereof are reduced since substances which evaporate during
sintering are not contained therein.
[0018] By using the nonreducing dielectric ceramic of the present
invention, the production of monolithic ceramic capacitors having
internal electrodes composed of an inexpensive base metal becomes
possible. As the base metal, not only elemental nickel and a Ni
alloy but also elemental copper and a Cu alloy having a superior
high-frequency performance can be used to manufacture small
high-performance monolithic ceramic capacitors.
[0019] The nonreducing dielectric ceramic of the present invention
can be applied to temperature-compensating capacitors and microwave
dielectric resonators. It can also be used as the material for
small-size high-capacitance monolithic ceramic capacitors since the
layers formed therefrom are thin. The scope of the industrial
application is significantly wide.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a diagram showing the X-ray diffraction pattern of
a dielectric ceramic Sample 34;
[0021] FIG. 2 is a diagram showing the X-ray diffraction pattern of
a dielectric ceramic Sample 20;
[0022] FIG. 3 is a ternary diagram of showing the
(Si.sub.1-.mu.-.nu.Ti.su- b..mu.Zr.sub..nu.)O.sub.2 content, the
(Mn.sub.1-.xi.Ni.sub..xi.)O content and the XO content in a (Si,
T)O.sub.2--MO--XO-type compound oxide;
[0023] FIG. 4 is a diagram showing the X-ray diffraction pattern of
a dielectric ceramic Sample 121;
[0024] FIG. 5 is a diagram showing the X-ray diffraction pattern of
a dielectric ceramic Sample 119; and
[0025] FIG. 6 is a ternary diagram showing the
(Si.sub.1-.mu.T.sub..mu.)O.- sub.2 content, the
(Mn.sub.1-.nu.M.sub..nu.) content and the Al.sub.2O.sub.3 content
in a (Si, T)O.sub.2--(Mn, M')O--Al.sub.2O.sub.3-b- ased compound
oxide.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Now, preferred embodiments of the present invention will be
described below by way of Examples.
Example 1
[0027] First, powders of CaCo.sub.3, SrCO.sub.3, BaCO.sub.3,
MgCO.sub.3, ZrO.sub.2, TiO.sub.2, MnCO.sub.3, NiO, HfO.sub.2 and
SiO.sub.2, each having purity of 99% or more, were prepared as the
raw materials for the main component of a nonreducing dielectric
ceramic and for a compound oxide added thereto.
[0028] These material powders were weighed in order to make
uncalcined main-component material powders represented by the
formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k(Zr.sub.1-w-x-y-zTi.sub.wMn.-
sub.xNi.sub.yHf.sub.z)O.sub.3
[0029] wherein subscripts a, b, c, w, x, y and z are as shown in
Tables 1 and 2 and subscript k is as shown in Tables 3 and 4. In
Tables 3 and 4, the sample numbers correspond to the sample numbers
in Tables 1 and 2.
1TABLE 1 Composition of Main-component Composition of Compound
Oxide Sample (Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).-
sub.k(Zr.sub.1-w-x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2-.beta.(Mn.sub.1--
.xi.Ni.sub..xi.)O-.gamma.CaO No. a b c w x y z m .alpha. .beta.
.gamma. .mu. .nu. .xi. 1 0.05 0 0 0.10 0.02 0.02 0.02 1.00 36.4
54.5 9.1 0.02 0.10 0.20 2 0.01 0.50 0 0.01 0.02 0.02 0.01 1.00 36.4
54.5 9.1 0.02 0.10 0.20 3 0.01 0 0.05 0.01 0.02 0.02 0.01 1.02 36.4
54.5 9.1 0.02 0.10 0.20 4 0.01 0 0 0.60 0.02 0.02 0.02 1.00 36.4
54.5 9.1 0.02 0.10 0.20 5 0.37 0.10 0.03 0.01 0.02 0.02 0.01 1.00
36.4 54.5 9.1 0.02 0.10 0.20 6 0.01 0 0 0.01 0.02 0.02 0.01 0.97
36.4 54.5 9.1 0.02 0.10 0.20 7 0.01 0 0 0.01 0.02 0.02 0.01 1.03
36.4 54.5 9.1 0.02 0.10 0.20 8 0.01 0 0 0.01 0.05 0 0.01 1.00 36.4
54.5 9.1 0.02 0.10 0.20 9 0.01 0 0 0.01 0 0.05 0.01 1.00 36.4 54.5
9.1 0.02 0.10 0.20 10 0.01 0 0 0.01 0.02 0.02 0.30 1.02 36.4 54.5
9.1 0.02 0.10 0.20 11 0.01 0 0 0.01 0.04 0.02 0.01 1.00 36.4 54.5
9.1 0.02 0.10 0.20 12 0.01 0 0 0.55 0.02 0.02 0.01 0.99 36.4 54.5
9.1 0.02 0.10 0.20 13 0.01 0 0 0.01 0.02 0.02 0.02 1.02 Li-type
glass 14 0.01 0 0 0.01 0.02 0.02 0.02 1.02 Li-B-type glass 15 0.01
0 0 0.01 0.02 0.02 0.01 1.01 36.4 54.5 9.1 0.02 0 0.20 16 0 0 0
0.37 0.01 0.02 0.02 0.99 33.3 66.7 0 0.02 0.10 0.20 17 0.30 0.10
0.02 0.01 0.02 0.02 0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20 18 0.01
0 0 0.01 0.01 0.02 0.02 1.00 19.7 0.3 80.0 0.02 0.10 0.20 19 0.01 0
0 0.01 0.01 0.02 0.02 1.00 5.0 15.0 80.0 0.02 0.10 0.20 20 0.01 0 0
0.01 0.01 0.02 0.02 1.00 45.4 6.2 48.4 0.02 0.10 0.20 21 0.01 0 0
0.37 0.02 0.02 0.02 0.99 36.4 54.5 9.1 0.02 0.10 0.20 22 0.30 0 0
0.30 0.02 0.02 0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20 23 0.24 0.16
0 0 0.02 0.02 0.01 0.99 36.4 54.5 9.1 0.02 0.10 0.20 24 0.31 0 0 0
0 0 0 0.99 36.4 54.5 9.1 0.02 0.10 0.20 25 0.45 0 0 0.30 0.02 0.02
0.02 0.99 36.4 54.5 9.1 0.02 0.10 0.20 26 0.30 0.10 0.01 0.01 0.02
0.02 0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20 27 0.01 0 0 0.37 0.04
0.01 0.01 1.02 36.4 54.5 9.1 0 0 0.20 28 0.01 0 0 0.01 0.01 0.04
0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20 29 0.01 0 0.03 0.01 0.02
0.02 0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20 30 0 0.45 0 0.45 0.02
0.02 0.01 1.00 36.4 54.5 9.1 0.02 0.10 0.20
[0030]
2TABLE 2 Composition of Main-component Composition of Compound
Oxide Sample (Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).-
sub.k(Zr.sub.1-w-x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2-.beta.(Mn.sub.1--
.xi.Ni.sub..xi.)O-.gamma.CaO No. a b c w x y z m .alpha. .beta.
.gamma. .mu. .nu. .xi. 31 0.01 0 0 0.20 0.01 0.02 0.11 0.98 36.4
54.5 9.1 0.02 0.10 0.20 32 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4
54.5 9.1 0.02 0.10 0.20 33 0.01 0 0 0.01 0 0 0.02 1.00 25.0 75.0 0
0.02 0.10 0.20 34 0.01 0 0 0.01 0.01 0.02 0.02 1.00 60.0 40.0 0
0.02 0.10 0.20 35 0.01 0 0 0.01 0.01 0.02 0.02 1.00 99.7 0.3 0 0.02
0.10 0.20 36 0.01 0 0 0.01 0.01 0.02 0.02 1.00 19.7 0.3 80.0 0.02
0.10 0.20 37 0.01 0 0 0.01 0.01 0.02 0.02 1.00 5.0 15.0 80.0 0.02
0.10 0.20 38 0.01 0 0 0.01 0.01 0.02 0.02 1.00 45.4 6.2 48.4 0.02
0.10 0.20 39 0.01 0 0 0.01 0.01 0.02 0.02 1.00 42.9 57.1 0 0.02
0.10 0.20 40 0.01 0 0 0.01 0.01 0.02 0.02 1.00 33.3 33.3 33.4 0.02
0.10 0.20 41 0.01 0 0 0.01 0.01 0.02 0.02 1.00 12.0 8.0 80.0 0.02
0.10 0.20 42 0.01 0 0 0.01 0.01 0.02 0.02 1.00 9.4 28.2 62.4 0.02
0.10 0.20 43 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4 54.5 9.1 0.40
0.10 0.20 44 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4 54.5 9.1 0.02
0.10 0.50 45 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4 54.5 9.1 0.02
0.10 1.00 46 0 0 0 0.37 0.01 0.02 0.02 0.99 33.3 66.7 0 0.02 0.10
0.20 47 0 0 0 0.37 0.01 0.02 0.02 0.98 25.0 50.0 25.0 0.02 0.10
0.20 48 0 0 0 0.37 0.01 0.02 0.02 0.98 25.0 50.0 25.0 0.04 0.10
0.30 49 0 0 0 0.37 0.01 0.02 0.02 0.98 22.2 55.6 22.2 0.02 0.10
0.20 50 0 0 0 0.37 0.01 0.02 0.02 0.98 29.9 46.7 23.4 0.02 0.10
0.20 51 0.01 0 0 0.01 0.01 0.02 0.02 1.00 24.5 75.5 0 0.02 0.10
0.20 52 0.01 0 0 0.01 0.01 0.02 0.02 1.00 16.5 3.0 80.5 0.02 0.10
0.20 53 0.01 0 0 0.01 0.01 0.02 0.02 1.00 4.5 15.5 80.0 0.02 0.10
0.20 54 0.01 0 0 0.01 0.01 0.02 0.02 1.02 36.4 54.5 9.1 0.50 0.10
0.20 55 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4 54.5 9.1 0.02 0.70
0.20 56 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4 54.5 9.1 0.30 0.50
0.20
[0031]
3TABLE 3 Composition of Main-component
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k(Zr.sub.1-w-y-zTi.sub.wMn.s-
ub.xNi.sub.yHf.sub.z)O.sub.3 Calcination Average particle diameter
after temperature Sample No. k milling and before calcining (.mu.m)
(.degree. C.) 1 1.00 0.4 1200 2 1.00 0.4 1200 3 1.00 0.4 1200 4
0.97 0.4 1200 5 1.00 0.4 1200 6 0.97 0.3 1200 7 0.97 0.4 1200 8
1.00 0.4 1200 9 1.00 0.4 1200 10 1.00 0.4 1300 11 1.00 0.5 1200 12
0.97 0.5 1200 13 1.01 0.4 1300 14 1.01 0.4 1300 15 1.01 0.5 950 16
0.96 0.8 950 17 1.00 0.6 1200 18 0.96 0.4 1000 19 1.00 1.0 1100 20
0.96 0.8 950 21 0.97 0.3 1200 22 1.00 0.5 1200 23 0.99 0.4 1200 24
0.99 0.5 1100 25 0.99 0.5 1200 26 1.00 0.4 1200 27 1.00 0.5 1100 28
1.00 0.4 1250 29 1.00 0.4 1250 30 1.00 0.4 1200
[0032]
4TABLE 4 Composition of Main-component
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k(Zr.sub.1-w-y-zTi.sub.wMn.s-
ub.xNi.sub.yHf.sub.z)O.sub.3 Calcination Average particle diameter
after temperature Sample No. k milling and before calcining (.mu.m)
(.degree. C.) 31 0.98 0.4 1200 32 0.99 0.3 1300 33 1.00 0.3 1300 34
1.00 0.3 1300 35 1.00 0.4 1250 36 1.00 0.4 1250 37 1.00 0.5 1200 38
1.00 0.5 1300 39 1.00 0.3 1300 40 1.00 0.3 1300 41 0.97 0.5 1100 42
0.97 0.4 1200 43 1.00 0.3 1300 44 1.00 0.3 1300 45 1.00 0.3 1300 46
0.99 0.3 1200 47 0.98 0.3 1200 48 0.98 0.3 1200 49 0.98 0.3 1200 50
0.97 0.5 1000 51 1.00 0.4 1200 52 1.00 0.4 1150 53 1.00 0.5 1100 54
1.01 0.4 1200 55 0.97 0.4 1150 56 0.99 0.5 1200
[0033] The uncalcined main-component material powders were
wet-blended and pulverized in a ball mill, and were dried. The
average particle diameter of the respective main-component material
powders is shown in Tables 3 and 4.
[0034] Next, the uncalcined main-component material powders were
calcined in air at the temperatures shown in Tables 3 and 4 for two
hours to obtain calcined main-component material powders.
[0035] In order to precisely adjust the proportion of the
components in each of the main-component material powders,
CaCO.sub.3, SrCO.sub.3, BaCO.sub.3 and MgCO.sub.3 were added to the
calcined main-component powder so that subscript m in the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.b-
Mg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
was that those shown in Tables 1 and 2. A predetermined amount of
the compound oxide shown in Tables 1 and 2 was then added to each
of the precisely-adjusted main-component material powders. In the
material powders Samples 13 and 14, a predetermined amount of
Li-type glass and Li--B-type glass were added in place of the
compound oxides and were mixed.
[0036] SiO.sub.2, TiO.sub.2, ZrO.sub.2, MnCO.sub.3, NiO and
CaCO.sub.3 were weighed in advance, and mixed, calcined and milled
to an average diameter of 1 .mu.m or less to obtain the compound
oxides shown in Tables 1 and 2 satisfying the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.su-
b..nu.)O.sub.2--.beta.(Mn.sub.1-.xi.Ni.sub..xi.)O--.gamma.CaO,
wherein subscripts .alpha., .beta., and .gamma. were molar percent
and subscripts .alpha., .beta., .gamma., .nu., and .xi. were as
shown in Tables 1 and 2.
[0037] A poly(vinyl butyral)-based binder and an organic solvent
such as ethanol were added to the resulting material powders and
were wet-blended in a ball mill to obtain ceramic slurries.
[0038] Each of the ceramic slurries was formed into sheet by the
doctor blade method and was cut to obtain rectangular ceramic green
sheets, each having a thickness of 12 .mu.m.
[0039] A conductive paste primarily composed of elemental nickel
(Ni) was applied by printing on the ceramic green sheets so as to
make conductive paste layers for forming internal electrodes of a
monolithic ceramic capacitor.
[0040] The ceramic green sheets provided with conductive paste
layers thereon were then laminated so that an end face of each
ceramic green sheet exposing the conductive paste appeared
alternately in the resulting ceramic green sheet laminate.
[0041] The laminate was heated to a temperature in the range of 240
to 350.degree. C. in an air or N.sub.2 atmosphere to burn out the
binder. Subsequently, the laminate was sintered at a temperature
shown in Tables 5 and 6 in a reducing atmosphere of
H.sub.2--N.sub.2--H.sub.2O gas to form a ceramic sintered compact.
Note that the sample numbers in Tables 5 and 6 correspond to the
sample numbers in Tables 1 and 2.
[0042] An silver (Ag) paste was applied on the two end faces of the
resulting ceramic sintered compact and was baked at 800.degree. C.
in air to form external electrodes electrically connected to the
internal electrodes.
[0043] The outer dimensions of the resulting monolithic ceramic
capacitor were 1.6 mm in width, 3.2 mm in length and 1.2 mm in
thickness. The thickness of each dielectric ceramic layer was 10
.mu.m. The total number of the effective dielectric ceramic layers
was 50.
[0044] Next, the electrical characteristics of the resulting
monolithic ceramic capacitor were examined. Electrostatic
capacitance and dielectric loss were determined at a frequency of 1
MHZ and a temperature of 25.degree. C. The relative dielectric
constant was calculated from the electrostatic capacitance.
Subsequently, insulation-resistance was measured by applying a DC
voltage of 50 V for two minutes at a temperature of 25.degree. C.
and the specific resistance was calculated therefrom. The
electrostatic capacitance was further examined at a frequency of 1
MHZ and at temperatures of 25.degree. C. and 125.degree. C. A rate
of change (TC) thereof was calculated using the formula (1)
described below. In the formula (1), C125 indicates the
electrostatic capacitance (pF) at a temperature of 125.degree. C.
and C25 indicates the electrostatic capacitance (pF) at a
temperature of 25.degree. C.
[0045] Formula (1):
TC={(C125-C25)/C25}.times.{1/(125-25)}.times.10.sup.6[-
ppm/.degree.C.]
[0046] Moreover, thirty-six test pieces for each sample were
subjected to a high-temperature loading lifetime test. A DC voltage
of 200 V was applied to the test pieces at a temperature of
140.degree. C. and the change in insulation-resistance over time
was examined. In this test, the life of the sample piece was
considered terminated when the insulation-resistance reached
10.sup.6 .OMEGA. or less. The average lifetime for each sample was
calculated.
[0047] Seventy-six test pieces for each sample were subjected to a
moisture-resistance loading test. A DC voltage of 100 V was applied
to the sample pieces at a temperature of 121.degree. C. under air
pressure 2 (relative humidity 100%) and the change in
insulation-resistance over time was measured. The test pieces were
deemed defective if the insulation-resistance thereof reached
10.sup.6 .OMEGA. or less within 200 hours.
[0048] The test pieces of the ceramic sintered compacts were
pulverized using a mortar to undergo a CuK.alpha. X-ray diffraction
analysis in order to obtain an intensity ratio of the maximum peak
of a different phase (i.e., every crystal phase which was not the
perovskite crystal phase) to the maximum peak characteristic of
perovskite crystal phase appearing at 2.theta.=25 to 35 degrees. It
is to be understood that because the internal electrodes were
pulverized together with the ceramic sintered compacts, the X-ray
diffraction chart has peaks relating to the internal electrodes.
These peaks were, accordingly, not different phases of the ceramic
and the intensity of these peaks were disregarded for purposes of
the comparison.
[0049] The results of the above-described examinations are shown in
Tables 5 and 6.
5TABLE 5 Baking Dielectric Relative Specific Average No. of Defects
Different Sample Temperature Loss Dielectric Resistance TC Lifetime
in Moisture- Phase Intensity No. (.degree. C.) (%) Constant
(.OMEGA. cm) (ppm/.degree. C.) (hr) resistance Test Rate 1 1300
0.01 45 >10.sup.13 -220 5 0/72 1.5 2 1300 0.01 36 >10.sup.13
-150 75 0/72 1.0 3 1350 Not Sintered 4 1300 0.25 120 >10.sup.13
-1050 45 0/72 3.5 5 1300 0.22 33 >10.sup.13 18 50 0/72 1.0 6
1250 0.40 31 >10.sup.13 -10 10 0/72 0.5 7 1350 Not Sintered 8
1250 0.60 31 6 .times. 10.sup.12 98 20 0/72 2.0 9 1250 0.02 31 4
.times. 10.sup.12 21 65 0/72 2.0 10 1350 Not Sintered 11 1250 0.47
31 5 .times. 10.sup.12 78 40 0/72 3.0 12 1300 0.01 97 >10.sup.13
-1000 20 0/72 3.5 13 1250 0.04 32 >10.sup.13 13 250 1/72 3.0 14
1250 0.05 32 >10.sup.13 15 270 6/72 3.0 15 1300 0.28 32 3
.times. 10.sup.12 5 95 0/72 5.5 16 1300 0.35 84 3 .times. 10.sup.12
-940 70 0/72 6.5 17 1300 0.49 32 3 .times. 10.sup.12 16 35 0/72 6.0
18 1350 0.87 31 3 .times. 10.sup.12 47 45 0/72 6.0 19 1350 0.53 32
3 .times. 10.sup.12 53 80 0/72 6.0 20 1300 0.43 32 3 .times.
10.sup.12 5 85 0/72 6.5 21 1300 0.01 85 >10.sup.13 -940 420 0/72
1.5 22 1300 0.10 55 >10.sup.13 -350 450 0/72 2.0 23 1300 0.05 46
>10.sup.13 13 425 0/72 1.0 24 1300 0.06 32 >10.sup.13 -5 420
0/72 3.0 25 1300 0.01 79 >10.sup.13 -670 430 0/72 2.0 26 1300
0.09 32 >10.sup.13 16 440 0/72 1.0 27 1300 0.07 83 >10.sup.13
-880 410 0/72 4.5 28 1300 0.01 31 >10.sup.13 10 410 0/72 1.5 29
1350 0.03 33 >10.sup.13 50 440 0/72 2.0 30 1300 0.02 96
>10.sup.13 -1000 420 0/72 2.5
[0050]
6TABLE 6 Baking Dielectric Relative Specific Average No. of Defects
Different Sample Temperature Loss Dielectric Resistance TC Lifetime
in Moisture- Phase Intensity No. (.degree. C.) (%) Constant
(.OMEGA. cm) (ppm/.degree. C.) (hr) resistance Test Rate 31 1300
0.01 57 >10.sup.13 -490 440 0/72 1.0 32 1300 0.01 32
>10.sup.13 4 >500 0/72 0.5 33 1300 0.02 33 >10.sup.13 -5
480 0/72 1.0 34 1300 0.03 32 >10.sup.13 -2 >500 0/72 1.0 35
1300 0.03 30 >10.sup.13 28 405 0/72 2.5 36 1350 0.08 31
>10.sup.13 47 420 0/72 3.0 37 1350 0.08 32 >10.sup.13 53 420
0/72 4.0 38 1350 0.01 32 >10.sup.13 5 >500 0/72 4.0 39 1300
0.01 32 >10.sup.13 2 >500 0/72 1.0 40 1350 0.01 28
>10.sup.13 -5 >500 0/72 1.0 41 1350 0.07 31 >10.sup.13 23
>500 0/72 4.0 42 1350 0.09 32 >10.sup.13 28 460 0/72 3.0 43
1350 0.02 32 >10.sup.13 5 490 0/72 0.5 44 1300 0.01 32
>10.sup.13 5 440 0/72 0.5 45 1300 0.01 32 >10.sup.13 5 420
0/72 0.5 46 1300 0.01 85 >10.sup.13 -940 460 0/72 0.5 47 1350
0.02 83 >10.sup.13 -820 440 0/72 1.5 48 1350 0.02 83
>10.sup.13 -950 480 0/72 1.5 49 1300 0.06 84 >10.sup.13 -790
460 0/72 2.0 50 1350 0.01 83 >10.sup.13 -860 460 0/72 3.0 51
1300 0.09 33 >10.sup.13 -2 325 0/72 1.0 52 1350 0.08 29
>10.sup.13 5 310 0/72 4.5 53 1350 0.07 31 >10.sup.13 48 340
0/72 4.5 54 1350 0.04 32 >10.sup.13 2 360 0/72 1.0 55 1350 0.02
30 >10.sup.13 -21 380 0/72 4.5 56 1350 0.03 31 >10.sup.13 -10
360 0/72 3.0
[0051] As apparent from Tables 5 and 6, the nonreducing dielectric
ceramics Samples 21 to 56 exhibited high specific resistances of
10.sup.13 .OMEGA..multidot.cm or more and low dielectric losses of
0.1% or less. The rate of the change in electrostatic capacitance
relative to temperature did not exceed -1000 ppm/.degree.C. and
this value may be adjusted to a desired value by changing the
composition. The average lifetime in a high-temperature loading
lifetime test at 150.degree. C. and 200 V was significantly long
and was 300 hours or more. Defects did not occur in the
moisture-resistance loading test at 121.degree. C./air pressure
2/100 V even after 200 hours had passed.
Example 2
[0052] A monolithic ceramic capacitor containing a compound oxide
and containing Li-type glass were manufactured to examine particle
diameter and breakdown-voltage.
[0053] More specifically, the same material powders as in Example 1
were weighed to prepare an uncalcined main-component material
powder represented by the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k-
(Zr.sub.1-w-z-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3 wherein
subscripts a, b, c, w, x, y, and z are as shown in Table 7 and
subscript k is as shown in Table 8. In Table 7, the sample numbers
correspond to the sample numbers in Table 8.
7TABLE 7 Composition of Main-component Composition of Compound
Oxide Sample (Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).-
sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2-.beta.(Mn.sub.1--
.xi.Ni.sub..xi.)O-.gamma.CaO No. a b c w x y z m .alpha. .beta.
.gamma. .mu. .nu. .xi. 61 0.01 0 0 0.01 0.01 0.02 0.02 1.00 36.4
54.5 9.1 0.02 0.10 0.20 62 0.01 0 0 0.01 0.01 0.02 0.02 1.00
Li-type glass
[0054]
8TABLE 8 Composition of Main-component
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-y-zTi.sub.wMn.s-
ub.xNi.sub.yHf.sub.z)O.sub.3 Sample Average Diameter after
Calcination No. k Milling before Calcining Temperature (.degree.
C.) 61 0.99 0.3 1300 62 0.99 0.3 1300
[0055] The above-described uncalcined main-component material
powders were wet-blended and pulverized in a ball mill, and were
dried. The average particle diameter of the main-component material
powders is shown in Table 8. Next, the uncalcined main-component
material powders were calcined at the temperatures shown in Table 8
in air for two hours to form calcined main-component material
powders.
[0056] CaCO.sub.3, SrCO.sub.3, BaCO.sub.3 and MgCO.sub.3 were added
to each of the calcined main-component powders so that subscript m
in the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn.-
sub.xNi.sub.yHf.sub.z)O.sub.3
[0057] was shown in Table 7. A predetermined amount of the compound
oxide shown in Table 7 was then added to the material powder Sample
61. In the material powder Sample 62, a predetermined amount of
Li-type glass was added in place of the compound oxide.
[0058] The same raw materials as in Example 1 were weighed in
advance, and mixed, calcined and milled to the same average
diameter as in Example 1 and to obtain the compound oxide shown in
Table 7 satisfying the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2--.beta.(Mn.sub.1-
-.xi.Ni.sub..xi.)O--.gamma.CaO, wherein subscripts .alpha., .beta.,
and were molar percent and subscripts .alpha., .beta., .gamma.,
.mu., .nu., and .xi. were as shown in Table 7.
[0059] Ceramic slurries were formed as in Example 1 from the
material powders and rectangular ceramic green sheets having a
thickness of 12 .mu.m were formed from the ceramic slurries. A
conductive paste mainly composed of nickel (Ni) as in Example 1 was
applied on these ceramic green sheets by printing to form
conductive paste layers for forming internal electrodes of
monolithic ceramic capacitors. The ceramic green sheets were
laminated as in Example 1 to obtain a ceramic green sheet
laminates. After burning out the binder contained in the laminates
as in Example 1, the laminates were baked in a reducing atmosphere
at the temperatures shown in Table 9 to form sintered ceramic
compacts. The sample numbers in Table 9 correspond to the sample
numbers in Table 7.
[0060] External electrodes were formed as in Example 1 on the two
end faces of each of the sintered ceramic compacts.
[0061] The outer dimensions of the resulting monolithic ceramic
capacitors were 1.6 mm in width, 0.8 mm in length, and 0.7 mm in
thickness. The thickness of the dielectric ceramic layer was 10
.mu.m. The total number of the effective dielectric ceramic layers
was 30.
[0062] Next, the particle diameter of monolithic ceramic
capacitors, thirty for each sample, was measured by scanning
electron microscopy (SEM). Breakdown-voltage was examined to
calculate standard deviation.
[0063] The results are shown in Table 9.
9TABLE 9 Com- Breakdown-voltage No. Baking pound SEM (V) Sam- of
Tempera- Oxide Particle Upper: Average ple Test ture or Glass
Diameter Lower: Standard No. Pieces (.degree. C.) added (.mu.m)
deviation 61 30 1300 Si-Mn- 1.0-3.0 152 Ca-type 52 compound oxide
62 30 1300 Li-type 1.0-10.0 1450 glass 145
[0064] As is apparent from Table 9, there were small variation in
the diameters of the nonreducing dielectric ceramic Sample 61 after
sintering and a little fluctuation in breakdown-voltage.
[0065] It is to be understood that although CaO was used as XO in
the compound oxide represented by the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.su-
b..mu.Zr.sub..nu.)O.sub.2--.beta.(Mn.sub.1-.xi.Ni.sub..xi.)O--.gamma.XO,
the scope of the invention is not limited by this example. Any one
of BaO, SrO and MgO may be used as XO and the same advantages and
effects can still be obtained as in this example.
[0066] Moreover, although elemental nickel was used as the base
metal constituting the internal electrodes, a nickel alloy, copper
(Cu) or a copper alloy may be used in place of elemental nickel.
The same advantages and effects obtained in this example can still
be achieved.
[0067] The ranges of the composition of the nonreducing dielectric
ceramic and the composition of the additional compound oxide are
limited as below.
[0068] The composition of the main-component (100 molar) satisfies
the formula:
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zT-
i.sub.wMn.sub.xNi.sub.yHf.sub.2)O.sub.3 wherein 0.ltoreq.a<0.5,
0.ltoreq.b<0.5, 0.ltoreq.c<0.05, 0.ltoreq.a+b+c<0.5,
0.98.ltoreq.m<1.03, 0.ltoreq.w<0.6, 0.ltoreq.x<0.05,
0.ltoreq.y<0.05, 0.ltoreq.z<0.3, 0.ltoreq.x+y.ltoreq.0.05,
and 0.ltoreq.w+x+y+z<0.6. When subscripts a and b are more than
0.5, respectively, as in the dielectric ceramics Samples 1 and 2 in
Tables 1 and 5, the average lifetime in high-temperature loading
lifetime test is shortened. When subscript c is 0.05 or more as in
the dielectric ceramic Sample 3, sinterability is drastically
degraded. When subscripts a, b, and c are in the ranges of
0.ltoreq.a<0.5, 0.ltoreq.b<0.5, and0.ltoreq.c<0.05but
total of a, b, and c is 0.5 or more as in Sample 5, dielectric loss
is increased, thereby shortening the average lifetime in the
high-temperature loading lifetime test. When subscript w is 0.6 or
more as in the dielectric ceramic Sample 4, dielectric loss and
rate of change in electrostatic capacitance relative to temperature
(TC) are increased and the average lifetime in the high-temperature
loading lifetime test is shortened. When subscript x is 0.05 or
more as in the dielectric ceramic Sample 8, dielectric loss is
increased and an average lifetime in the high-temperature loading
lifetime test is decreased. When subscript y is 0.05 or more as in
the dielectric ceramic Sample 9, the average lifetime in the
high-temperature loading lifetime test is shortened. When subscript
z is 0.3 or more as in the dielectric ceramic Sample 10,
sinterability is degraded drastically. When the total of subscripts
x and y exceeds 0.05 as in the dielectric ceramic Sample 11,
dielectric loss is increased and an average lifetime in the
high-temperature loading lifetime test is shortened. When the total
of subscripts w, x, y, and z is 0.6 or more as in the dielectric
ceramic Sample 12, an average lifetime in the high-temperature
loading test is shortened.
[0069] In view of the above, the Sr content a is preferably in the
range of 0.ltoreq.a<0.5, the Ba content b is preferably in the
range of 0.ltoreq.b<0.5 and the Mg content c is preferably in
the range of 0.ltoreq.c<0.05. Meanwhile, the sum of a, b, and c
is preferably in the range of 0.ltoreq.a+b+c<0.5. The Ti content
w is preferably in the range of 0.ltoreq.w<0.6, the Mn content x
is preferably in the range of 0.ltoreq.x<0.05, the Ni content y
is preferably in the range of 0.ltoreq.y <0.05 and Hf content z
is preferably in the range of 0.ltoreq.z<0.3. Meanwhile, the sum
of x and y is preferably in the range of 0.ltoreq.x+y.ltoreq.0.05
and the sum of w, x, y, and z is preferably in the range of
0.ltoreq.w+x+y+z<0.6.
[0070] As in the dielectric ceramic Sample 6 in Tables 1 and 5,
when subscript m is less than 0.98, dielectric loss is increased
and the average lifetime in the high-temperature loading lifetime
test is shortened. When subscript m is 1.03 or more as in the
dielectric ceramic Sample 7, sinterability is degraded drastically.
Subscript m is, therefore, preferably in the range of
0.98.ltoreq.m<1.03.
[0071] When glass containing volatile components such as Li or B is
used in place of the additional compound oxide, the volatilization
amount and the volatilization time vary between samples. As a
consequence, some particles exhibit abnormal growth while others
exhibit no growth resulting in irregular particle diameters.
Accordingly, even when the main-component of the nonreducing
dielectric ceramic satisfies the above-described ranges, the number
of defective pieces in moisture-resistance loading test increases
as in the dielectric ceramics Samples 13 and 14 in Table 1 and if
the compound oxide added thereto contained Li-type glass or Li--B
type glass.
[0072] Also, as in the dielectric ceramic Sample 62 in Table 7 and
9, fluctuation in breakdown-voltage is increased, thereby degrading
the reliability.
[0073] In view of the above, the additional compound oxide is
preferably a compound oxide containing neither Li-type nor Li--B
type glass which satisfies the formula (Si, T)O.sub.2--MO--XO
wherein T is at least one selected from the group consisting of Ti
and Zr, MO is at least one selected from the group consisting of
MnO and NiO, and XO is at least one selected from the group BaO,
SrO, CaO and MgO.
[0074] When the intensity ratio of the maximum peak of the
different phase (i.e., every crystal phase not the perovskite
crystal phase) to the maximum peak characteristic of perovskite
crystal phase appearing at 2.theta.=25 to 35 degrees exceeds about
5% in the CuK.alpha. X-ray diffraction analysis, dielectric loss is
undesirably increased and the average lifetime in the
high-temperature loading lifetime test is undesirably shortened as
demonstrated by the dielectric ceramics Samples 15 to 20 in Table
5. Accordingly, the intensity ratio of the maximum peak of the
different phase relative to the maximum peak of the perovskite
crystal phase is preferably about 5% or less and more preferably
about 3% or less.
[0075] As is apparent from the dielectric ceramics Samples 15 to 20
in Tables 1, 3 and 5, the following factors must be satisfied in
addition to satisfying the above-described composition ranges of
the main-component and complying with the types of the compound
oxide in order to prevent the intensity ratio of the maximum phase
of the different phase to the maximum peak of the perovskite
crystal phase from exceeding about 5%. First, an average particle
diameter of the main-component material is about 0.5 .mu.m or less
after milling and before calcining. Second, an A/B site ratio in
the main-component material is in the range of about 0.97 to 1.01
before calcining. Third, a calcination temperature is in the range
of about 1000 to 1300.degree. C.
[0076] FIG. 1 is an X-ray diffraction diagram of the dielectric
ceramic Sample 34 in which the intensity ratio of the maximum peak
of the different peak relative to the maximum peak of the
perovskite crystal phase is 1.0%. FIG. 2 is an X-ray diffraction
diagram of the dielectric ceramic Sample 20 having the intensity
ratio of 6.5%. The asterisked peaks in the charts indicate peaks
indicating the perovskite crystal phase. The peaks not indicating
the perovskite crystal phase are not asterisked.
[0077] Preferably, a compound oxide represented by the formula
.alpha.(Si.sub.1-.mu.-.nu.Ti.sub..mu.Zr.sub..nu.)O.sub.2--.beta.(Mn.sub.1--
.xi.Ni.sub..xi.)O--.gamma.XO
[0078] where (a, b, and g are molar percent and XO is one selected
from the group consisting of BaO, SrO, CaO, and MgO), wherein
0.ltoreq..mu.<0.5, 0.ltoreq..nu.<0.7,
0.ltoreq..xi..ltoreq.1.0, 0.ltoreq..mu.+.nu..ltoreq.0.7 and wherein
the (Si.sub.1-.mu.-.nu.Ti.sub..- mu.Zr.sub..nu.)O.sub.2 content,
the (Mn.sub.1-.xi.Ni.sub..xi.)O content and the XO content lie
within the region in the ternary diagram in FIG. 3 surrounded by
points A (.alpha.=25.0, .beta.=75.0, .gamma.=0), B(.alpha.=100.0,
.beta.=0, .gamma.=0), C (.alpha.=20.0, .beta.=0, .gamma.=80.0), and
D (.alpha.=5.0, .beta.=15.0, .gamma.=80.0) including the lines AB,
AD, and DC but excluding the line BC is used as the compound oxide.
By using such an oxide, significantly long lifetime of 400 hours or
more in the high-temperature loading lifetime test can be achieved
as shown by the dielectric ceramics Samples 21 to 50 in Tables 1,
2, 5, and 6.
Example 3
[0079] Nonreducing dielectric ceramics having the same
main-component as Example 1 added with the compound oxides of
different compositions were formed.
[0080] First, powders of CaCo.sub.3, SrCO.sub.3, BaCO.sub.3,
MgCO.sub.3, ZrO.sub.2, TiO.sub.2, MnCO.sub.3, NiO, HfO.sub.2,
SiO.sub.2 and Al.sub.2O.sub.3, each having purity of 99% or more,
were prepared as the raw materials for the main-component and for
the compound oxide.
[0081] These material powders were weighed to obtain an uncalcined
main-component material powder represented by the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k(Zr.sub.1-w-x-y-zTi.sub.wMn-
.sub.xNi.sub.yHf.sub.z)O.sub.3 wherein subscripts a, b, c, w, x, y,
and z were as shown in Tables 10 and 11 and subscript k was as
shown in Tables 12 and 13. In Tables 12 and 13, the sample numbers
correspond to the sample numbers in Tables 10 and 11.
10TABLE 10 Composition of Compound Oxide Composition of
Main-component .alpha.(Si.sub.1-.mu.Ti.sub..mu.)O.sub.2- Sample
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-
-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.beta.(Mn.sub.1-.nu.Sr.sub..nu.- )O-.gamma.Al.sub.2O.sub.3 No. a b
c w x y z m .alpha. .beta. .gamma. .mu. .nu. 101 0.50 0 0 0.20 0.02
0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10 102 0.01 0.50 0 0.05 0.02
0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10 103 0.01 0 0.05 0.01 0.02
0.02 0.02 1.02 51.6 36.3 12.1 0.20 0.10 104 0.37 0.10 0.03 0.03
0.02 0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10 105 0.01 0 0 0.60 0.02
0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10 106 0.01 0 0 0.01 0.05 0
0.01 1.00 51.6 36.3 12.1 0.20 0.10 107 0.01 0 0 0.01 0 0.05 0.02
1.00 51.6 36.3 12.1 0.20 0.10 108 0.01 0 0 0.01 0.02 0.02 0.30 1.02
51.6 36.3 12.1 0.20 0.10 109 0.01 0 0 0.01 0.04 0.02 0.01 1.00 51.6
36.3 12.1 0.20 0.10 110 0.01 0 0 0.55 0.02 0.02 0.01 1.00 51.6 36.3
12.1 0.20 0.10 111 0.01 0 0 0.01 0.02 0.02 0.01 0.97 51.6 36.3 12.1
0.20 0.10 112 0.01 0 0 0.01 0.02 0.02 0.02 1.03 51.6 36.3 12.1 0.20
0.10 113 0.01 0 0 0.01 0.01 0.02 0.02 1.00 Li-type glass 114 0.01 0
0 0.01 0.01 0.02 0.02 1.00 Li-B-type glass 115 0.01 0 0 0.01 0.01
0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10 116 0.01 0 0 0.01 0.01 0.02
0.02 1.00 0 60.0 40.0 -- 0.10 117 0.01 0 0 0.01 0.01 0.02 0.02 1.00
60.0 0 40.0 0.20 -- 118 0.01 0 0 0.01 0.01 0.02 0.02 1.00 25.0 75.0
0 0.20 0.10 119 0.01 0 0 0.01 0.01 0.02 0.01 1.01 78.0 19.0 3.0
0.20 0.10 120 0 0 0 0.37 0.01 0.02 0.01 1.01 51.6 36.3 12.1 0.20
0.10 121 0.01 0 0 0.01 0.01 0.02 0.01 1.00 51.6 36.3 12.1 0.20 0.10
122 0 0 0 0.33 0.01 0.02 0.01 0.99 51.6 36.3 12.1 0.20 0.10 123 0 0
0 0.33 0.01 0.02 0.01 0.99 51.6 36.3 12.1 0.20 0.10 124 0 0 0 0.37
0.01 0.02 0.01 0.99 51.6 36.3 12.1 0.20 0.10 125 0.25 0 0 0.25 0.01
0.02 0.01 1.01 51.6 36.3 12.1 0.20 0.10 126 0.25 0 0 0.25 0.01 0.02
0.01 1.01 51.6 36.3 12.1 0.20 0.10 127 0 0.25 0 0.25 0.01 0.02 0.01
1.00 51.6 36.3 12.1 0.20 0.10 128 0 0.25 0 0.25 0.01 0.02 0.01 1.00
51.6 36.3 12.1 0.20 0.10 129 0.31 0 0 0.03 0.01 0.02 0.01 1.00 51.6
36.3 12.1 0.20 0.10 130 0.31 0 0 0.03 0.01 0.02 0.01 1.00 51.6 36.3
12.1 0.20 0.10
[0082]
11TABLE 11 Composition of Compound Oxide Composition of
Main-component .alpha.(Si.sub.1-.mu.Ti.sub..mu.)O.sub.2- Sample
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-
-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.beta.(Mn.sub.1-.nu.Sr.sub..nu.- )O-.gamma.Al.sub.2O.sub.3 No. a b
c w x y z m .alpha. .beta. .gamma. .mu. .nu. 131 0.01 0 0 0.01 0.01
0.02 0.02 1.01 32.8 58.4 8.8 0.20 0.10 132 0.01 0 0 0.01 0.01 0.02
0.02 1.01 32.8 58.4 8.8 0.20 0.10 133 0.01 0 0 0.01 0.01 0.02 0.02
1.01 43.3 48.0 8.7 0.20 0.10 134 0.01 0 0 0.01 0.01 0.02 0.02 1.01
44.1 29.4 26.5 0.20 0.10 135 0.01 0 0 0.01 0.01 0.02 0.02 1.01 64.0
18.9 17.1 0.20 0.10 136 0.01 0 0 0.01 0.01 0.02 0.02 1.00 81.0 10.0
9.0 0.20 0.10 137 0.01 0 0 0.01 0.01 0.02 0.02 1.00 80.0 10.0 10.0
0.20 0.10 138 0.01 0 0 0.01 0.01 0.02 0.02 1.00 80.0 1.0 19.0 0.20
0.10 139 0.01 0 0 0.01 0.01 0.02 0.02 1.00 80.0 19.0 1.0 0.20 0.10
140 0.01 0 0 0.01 0.01 0.02 0.02 1.00 9.5 50.0 40.5 0.20 0.10 141
0.01 0 0 0.01 0.01 0.02 0.02 1.00 10.0 50.0 40.0 0.20 0.10 142 0.01
0 0 0.01 0.01 0.02 0.02 1.00 10.0 89.5 0.5 0.20 0.10 143 0.01 0 0
0.01 0.01 0.02 0.02 1.00 10.0 20.0 70.0 0.20 0.10 144 0.01 0 0 0.01
0.01 0.02 0.02 1.00 19.0 10.0 71.0 0.20 0.10 145 0.01 0 0 0.01 0.01
0.02 0.02 1.00 20.0 10.0 70.0 0.02 0.10 146 0.01 0 0 0.01 0.01 0.02
0.02 1.00 29.5 0.5 70.0 0.20 0.10 147 0.01 0 0 0.01 0.01 0.02 0.02
1.00 68.1 24.0 7.9 0.20 0.10 148 0.01 0 0 0.01 0.01 0.02 0.02 1.00
35.5 56.2 8.3 0.20 0.60
[0083]
12TABLE 12 Composition of Main-component
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-y-zTi.sub.wMn.s-
ub.xNi.sub.yHf.sub.z)O.sub.3 Calcination Average particle diameter
after temperature Sample No. k milling and before calcining (.mu.m)
(.degree. C.) 101 1.00 0.4 1200 102 1.00 0.3 1200 103 1.00 0.4 1200
104 1.00 0.4 1200 105 0.97 0.5 1200 106 1.00 0.4 1200 107 1.00 0.4
1200 108 1.00 0.4 1300 109 1.00 0.4 1200 110 1.00 0.4 1200 111 0.97
0.3 1200 112 0.97 0.4 1200 113 1.00 0.5 1300 114 1.00 0.5 1300 115
1.00 0.4 1300 116 1.00 0.4 1300 117 1.00 0.3 1300 118 1.00 0.4 1300
119 0.96 0.5 1100 120 1.01 0.7 950 121 1.00 0.3 1300 122 0.99 0.3
1200 123 0.99 0.6 1050 124 0.99 0.3 1200 125 1.00 0.3 1200 126 0.96
0.6 1000 127 1.00 0.3 1200 128 0.95 1.0 950 129 1.00 0.3 1200 130
0.99 0.5 950
[0084]
13TABLE 13 Composition of Main-component Composition of
Main-component (Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.s-
ub.c).sub.m(Zr.sub.1-w-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
Calcination Average particle diameter after temperature Sample No.
k milling and before calcining (.mu.m) (.degree. C.) 131 1.00 0.4
1300 132 1.00 0.6 950 133 1.00 0.3 1300 134 1.00 0.4 1250 135 1.00
0.4 1200 136 1.00 0.5 1100 137 1.00 0.5 1150 138 0.97 0.4 1200 139
1.00 0.3 1300 140 1.00 0.3 1300 141 1.00 0.3 1300 142 1.00 0.4 1300
143 1.00 0.5 1100 144 1.00 0.5 1150 145 1.00 0.5 1150 146 1.00 0.3
1200 147 1.00 0.4 1250 148 0.97 0.3 1200
[0085] The uncalcined main-component material powders were
wet-blended and pulverized in a ball mill, and were dried as in
Example 1. The average particle diameters of the main-component
material powders are shown in Tables 12 and 13.
[0086] Next, the uncalcined main-component material powders were
calcined in air at the temperatures shown in Tables 3 and 4 for two
hours to obtain calcined main-component material powders.
[0087] CaCO.sub.3, SrCO.sub.3, BaCO.sub.3 and MgCO.sub.3 were then
weighed and were added to the calcined main-component powder so
that subscript m in the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w--
x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3 was as shown in
Tables 10 and 11. A predetermined amount of compound oxide shown in
Tables 10 and 11 was then added to the main-component material
powder. A predetermined amount of Li-type glass was added to the
material powder Sample 113 in place of the above-described compound
oxide. A predetermined amount of Li--B-type glass was added to the
material powder Sample 114. Predetermined amounts of uncalcined Si
oxide, Mn oxide and Al oxide were added and mixed to the material
powder Sample 115.
[0088] SiO.sub.2, TiO.sub.2, MnCO.sub.3, SrCO.sub.3 and
Al.sub.2O.sub.3 were weighed in advance, and mixed, calcined, and
milled to an average diameter of 1 .mu.m or less and to obtain the
compound oxides shown in Tables 10 and 11 satisfying the formula
a(Si.sub.1-.mu.Ti.sub..mu.)O.sub.-
2--.beta.(Mn.sub.1-.nu.Sr.sub..nu.)O--.gamma.Al.sub.2O.sub.3,
wherein subscripts a, b and g were molar percent and subscripts a,
b, g, m and n were as shown in Tables 10 and 11.
[0089] Ceramic slurries were formed by wet-blending the resulting
material powders as in Example 1, were formed into sheets, and were
cut to obtain the ceramic green sheets having the same thickness
and shape as in Example 1.
[0090] A conductive paste primarily composed of nickel (Ni) was
applied by printing on the ceramic green sheets so as to form
conductive paste layers for forming internal electrodes of
monolithic ceramic capacitors as in Example 1. Plural ceramic green
sheets were laminated to form ceramic green sheet laminates.
[0091] After the laminate was fired to burn out the binder
contained therein as in Example 1, the laminate was baked at a
temperature shown in Tables 14 and 15 in a reducing atmosphere to
form a ceramic sintered compact. Note that the sample numbers in
Tables 14 and 15 correspond to the sample numbers in Table 10 and
11.
[0092] External electrodes electrically connected with the internal
electrodes were formed on the ceramic sintered compact as in
Example 1.
[0093] A Ni plating solution composed of nickel sulfate, nickel
chloride and boric acid was prepared and Ni plating layers were
formed on the surfaces of the external electrodes by barrel
plating.
[0094] On the resulting Ni plating layers, Sn plating layers were
formed using a carboxylic-acid-based Sn plating solution by barrel
plating.
[0095] The outer dimensions of the resulting monolithic ceramic
capacitor were 1.6 mm in width, 3.2 mm in length and 1.2 mm in
thickness. The thickness of each dielectric ceramic layer was 10
.mu.m. The total number of the effective dielectric ceramic layers
was 50.
[0096] Next, electrical characteristics of the monolithic ceramic
capacitor were examined under the same condition as those of
Example 1. That is, electrostatic capacitance and dielectric loss
were determined and relative dielectric constant was calculated
from the electrostatic capacitance obtained. Subsequently,
insulation-resistance was measured and the specific resistance was
calculated therefrom. The electrostatic capacitance was further
examined and a rate of change (TC) thereof was calculated as in
Example 1.
[0097] Moreover, thirty-six test pieces for each sample were
subjected to a high-temperature loading life test as in Example 1
to examine change in insulation-resistance over time. The lifetimes
of the sample pieces were determined using the same standard as in
Example 1 and an average lifetime for each sample was
determined.
[0098] A moisture-resistance loading test was also conducted as in
Example 1 to observe the change in insulation-resistance over time.
The test pieces considered defective using the same standard as in
Example 1 were counted.
[0099] These ceramic sintered compacts underwent a CuK.alpha. X-ray
diffraction analysis to obtain an intensity ratio of the maximum
peaks. The results are shown in Tables 14 and 15.
14TABLE 14 Baking Dielectric Relative Specific Average No. of
Defects Different Sample Temperature Loss Dielectric Resistance TC
Lifetime in Moisture- Phase Intensity No. (.degree. C.) (%)
Constant (.OMEGA. cm) (ppm/.degree. C.) (hr) resistance Test Rate
101 1200 0.01 62 >10.sup.13 -420 75 0/72 2.0 102 1250 0.01 26
>10.sup.13 -150 90 0/72 1.0 103 1350 Not Sintered 104 1250 0.22
34 >10.sup.13 37 50 0/72 1.5 105 1200 0.08 110 >10.sup.13
-1100 45 0/72 3.5 106 1250 0.45 30 6 .times. 10.sup.12 90 35 0/72
1.5 107 1250 0.02 30 4 .times. 10.sup.12 18 85 0/72 1.5 108 1350
Not Sintered 109 1250 0.38 30 6 .times. 10.sup.12 72 60 0/72 2.5
110 1200 0.03 94 >10.sup.13 -980 50 0/72 3.0 111 1250 0.40 30
>10.sup.13 -8 35 0/72 0.5 112 1350 Not Sintered 113 1250 0.04 32
>10.sup.13 13 250 1/72 3.0 114 1250 0.05 32 >10.sup.13 15 270
6/72 3.0 115 1350 0.02 32 >10.sup.13 -5 300 1/72 1.5 116 1350
Not Sintered 117 1350 0.05 29 >10.sup.13 -7 320 2/72 2.5 118
1300 0.01 32 >10.sup.13 5 380 1/72 1.5 119 1350 0.47 32
>10.sup.13 -5 80 0/72 5.5 120 1200 0.53 81 >10.sup.13 -960 85
0/72 6.5 121 1250 0.01 30 >10.sup.13 -10 >500 0/72 0.5 122
1250 0.01 70 >10.sup.13 -740 480 0/72 0.5 123 1250 0.17 66
>10.sup.13 -780 100 0/72 6.0 124 1250 0.01 81 >10.sup.13 -940
470 0/72 0.5 125 1250 0.01 72 >10.sup.13 -720 420 0/72 0.5 126
1250 0.13 69 >10.sup.13 -760 75 0/72 6.5 127 1250 0.01 63
>10.sup.13 -440 430 0/72 0.5 128 1250 0.25 60 >10.sup.13 -460
90 0/72 8.5 129 1250 0.01 35 >10.sup.13 -20 440 0/72 0.5 130
1250 0.15 33 >10.sup.13 -5 120 0/72 6.0
[0100]
15TABLE 15 Baking Dielectric Relative Specific Average No. of
Defects Different Sample Temperature Loss Dielectric Resistance TC
Lifetime in Moisture- Phase Intensity No. (.degree. C.) (%)
Constant (.OMEGA. cm) (ppm/.degree. C.) (hr) resistance Test Ratio
131 1250 0.01 31 >10.sup.13 3 480 0/72 1.0 132 1250 0.12 29
>10.sup.13 16 160 0/72 5.5 133 1250 0.01 31 >10.sup.13 -2
>500 0/72 0.5 134 1250 0.01 29 >10.sup.13 -12 440 0/72 2.0
135 1250 0.01 30 >10.sup.13 -15 440 0/72 3.0 136 1300 0.04 31
>10.sup.13 8 280 0/72 4.0 137 1300 0.03 31 >10.sup.13 6 420
0/72 3.5 138 1350 0.06 30 >10.sup.13 9 400 0/72 4.5 139 1300
0.01 31 >10.sup.13 -5 430 0/72 1.5 140 1250 0.07 29
>10.sup.13 12 260 0/72 2.5 141 1200 0.07 29 >10.sup.13 11 440
0/72 2.5 142 1250 0.09 31 >10.sup.13 17 400 0/72 3.0 143 1250
0.01 28 >10.sup.13 6 480 0/72 4.0 144 1250 0.03 28 >10.sup.13
-2 290 0/72 3.5 145 1250 0.02 28 >10.sup.13 -4 420 0/72 3.5 146
1250 0.05 28 >10.sup.13 -11 400 0/72 3.5 147 1200 0.01 34
>10.sup.13 -21 320 0/72 1.0 148 1250 0.02 31 >10.sup.13 -10
380 0/72 1.0
[0101] As is apparent from Tables 14 and 15, the nonreducing
dielectric ceramics Samples 121, 122, 124, 125, 127, 129, 131 and
133 to 148 exhibited high specific resistances of 1013
.OMEGA..multidot.cm or more and low dielectric losses of 0.1% or
less. The rate of change in electrostatic capacitance relative to
temperature was within -1000 ppm/.degree.C. This rate can be
adjusted to a desired value by changing the composition. The
average lifetime in the high-temperature loading lifetime test at
150.degree. C./200 V was significantly long, i.e., 200 hours or
more. No defective pieces were found after 200 hours in the
moisture-resistance loading test at 121.degree. C./air pressure
2/100 V.
Example 4
[0102] A monolithic ceramic capacitor containing compound oxide and
that containing Li-type glass were formed to examine the
fluctuation in particle diameter and in breakdown-voltage.
[0103] The same raw materials as in Example 1 were used. These
materials were weighed to obtain an uncalcined main-component
material powder represented by the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m-
(Zr.sub.1-w-x-y-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3 wherein
subscripts a, b, c, w, x, y, and z are as shown in Table 16 and
subscript k is as shown in Table 17. The sample numbers in Table 17
correspond to the sample numbers in Table 16.
16TABLE 16 Composition of Compound Oxide Composition of
Main-component .alpha.(Si.sub.1-.mu.Ti.sub..mu.)O.sub.2- Sample
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-
-zTi.sub.wMn.sub.xNi.sub.yHf.sub.z)O.sub.3
.beta.(Mn.sub.1-.nu.Sr.sub..nu.- )O-.gamma.Al.sub.2O.sub.3 No. a b
c w x y z m .alpha. .beta. .gamma. .mu. .nu. 151 0.01 0 0 0.01 0.01
0.02 0.02 1.00 51.6 36.3 12.1 0.20 0.10 152 0.01 0 0 0.01 0.01 0.02
0.02 1.00 Li-type glass
[0104]
17TABLE 17 Composition of Main-component
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-y-zTi.sub.wMn.s-
ub.xNi.sub.yHf.sub.z)O.sub.3 Sample Average Particle Diameter after
Calcination No. k Milling before Calcining (82 m) Temperature
(.degree. C.) 151 0.99 0.3 1300 152 0.99 0.3 1300
[0105] The uncalcined main-component material powders were then
wet-blended and pulverized in a ball mill, and were dried. An
average particle diameter of the main-component material powder at
this stage was as shown in Table 17.
[0106] The material powder for main-component was calcined for two
hours in air at a temperature shown in Table 17 to form calcined
material powder for main-component.
[0107] In order to precisely adjust the proportion of the
components contained in the powder, CaCO.sub.3, SrCO.sub.3,
BaCO.sub.3 and MgCO.sub.3 were added so that subscript m in the
formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn-
.sub.xNi.sub.yHf.sub.z)O.sub.3 was as shown in Table 16. A
predetermined amount of compound oxide shown in Table 16 is added
to the material powder Sample 151 and Li-type glass was added in
place of the compound oxide to the material powder Sample 152.
[0108] The same raw materials as in Example 3 were weighed in
advance, and mixed, calcined and milled to the same average
diameter as in Example 3 so as to obtain the compound oxides shown
in Table 16 satisfying the formula
.alpha.(Si.sub.1-.mu.Ti.sub..mu.)O.sub.2--.beta.(Mn.sub.1-.nu.Sr.-
sub..nu.)O--.gamma.Al.sub.2O.sub.3, wherein subscripts .alpha.,
.beta., and .gamma. were molar percent and subscripts .alpha.,
.beta., .gamma., .mu., and .nu. were as shown in Table 16.
[0109] Ceramic slurries were made using the material powders as in
Example 3. Rectangular ceramic green sheets having a thickness of
12 .mu.m were then made from these ceramic slurries. A conductive
paste primarily composed of nickel (Ni) was applied by printing on
the ceramic green sheets so as to obtain conductive paste layers
for forming internal electrodes of a monolithic ceramic capacitor.
These ceramic green sheets were laminated as in Example 3 to form a
ceramic green sheet laminate. The laminate was heated to burn out
the binder and was then baked at a temperature shown in Table 18 in
a reducing atmosphere to obtain a ceramic sintered compact. The
sample numbers in Table 18 correspond to the sample numbers in
Table 16.
[0110] External electrodes for providing electrical connecting to
the internal electrodes were formed on the ceramic sintered compact
as in Example 3. Ni plating layers and then Sn plating layers were
formed on the surfaces of the external electrodes as in Example
3.
[0111] The outline dimension of the resulting monolithic ceramic
capacitor was 1.6 mm in width, 3.2 mm in length and 1.2 mm in
thickness. The thickness of each dielectric ceramic layer was 10
.mu.m. The total number of the effective dielectric ceramic layers
was 80.
[0112] Next, the particle diameter of monolithic ceramic
capacitors, thirty for each sample, was measured by a scanning
electron microscope (SEM). Breakdown-voltage was also measured and
standard deviation was determined. The results are shown in Table
18 below.
18TABLE 18 Com- Breakdown-voltage No. Baking pound SEM (V) Sam- of
Tempera- Oxide Particle Upper: Average ple Test ture or Glass
diameter Lower: Standard No. Pieces (.degree. C.) added (.mu.m)
deviation 151 30 1230 Si-Mn- 0.7-1.0 1776 Al-type 73 compound oxide
152 30 1300 Li-type 1.0-10.0 1450 glass 145
[0113] As is apparent from Table 18, the nonreducing dielectric
ceramic Sample 151 containing compound oxide exhibited little
variation in the particle diameter after baking and
in-breakdown-voltage.
[0114] It is to be understood that although Ti was used as T and Sr
was used as M' in the compound oxide represented by the formula
.alpha.(Si.sub.1-.mu.T.sub..mu.)O.sub.2--.beta.(Mn.sub.1-.nu.M'.sub..nu.)-
O--.gamma.Al.sub.2O.sub.3 in this Example, the scope of the present
invention is not limited to this compound oxide. Alternatively, T
may be Zr and M' may be one selected from the group consisting of
Ni, Ba, Ca and Mg may be used and the same advantages and effects
can still be obtained as in this example.
[0115] Moreover, although elemental nickel was used as the base
metal constituting the internal electrodes, a nickel alloy, copper
(Cu) or a copper alloy may be used in place of elemental nickel.
The same advantages and effects can still be obtained as in this
example.
[0116] The ranges of the composition in the nonreducing dielectric
ceramic and the composition of the additional compound oxide were
limited as below.
[0117] In the main-component (100 molar) represented by the formula
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.m(Zr.sub.1-w-x-y-zTi.sub.wMn-
.sub.xNi.sub.yHf.sub.z)O.sub.3 wherein 0.ltoreq.a<0.5,
0.ltoreq.b<0.5, 0.ltoreq.c<0.05, 0.ltoreq.a+b+c<0.5,
0.98.ltoreq.m<1.03, 0.ltoreq.w<0.06, 0.ltoreq.x<0.05,
0.ltoreq.y<0.05, 0.ltoreq.z<0.3, 0.ltoreq.x+y.ltoreq.0.05,
and 0.ltoreq.w+x+y+z<0.6, when subscripts a and b are more than
0.5, respectively, as in the dielectric ceramics Samples 101 and
102 in Tables 10 and 14, the average lifetime in high-temperature
loading lifetime test is shortened. When subscript c is 0.05 or
more as in Sample 103, sinterability is significantly degraded.
When 0.ltoreq.a<0.5, 0.ltoreq.b<0.5, and 0.ltoreq.c<0.05
but total of a, b, and c is 0.5 or more as in Sample 104,
dielectric loss is increased resulting in a shorter average
lifetime in the high-temperature loading lifetime test. When
subscript w is 0.6 or more as in the dielectric ceramic Sample 105,
dielectric loss and rate of change in electrostatic capacitance
relative to temperature (TC) are increased and the average lifetime
in the high-temperature loading lifetime test is shortened. When
subscript x is 0.05 or more as in the dielectric ceramic Sample
106, dielectric loss is increased and the average lifetime in the
high-temperature loading lifetime test is decreased. When subscript
y is 0.05 or more as in the dielectric ceramic Sample 107, the
average lifetime in the high-temperature loading lifetime test is
shortened. When subscript z is 0.3 or more as in the dielectric
ceramic Sample 108, sinterability thereof is degraded drastically.
When the total of subscripts x and y exceeded 0.05 as in the
dielectric ceramic Sample 109, dielectric loss is increased and the
average lifetime in the high-temperature loading lifetime test is
shortened. When the total of subscripts w, x, y, and z is 0.6 or
more as in the dielectric ceramic Sample 110, the average lifetime
in the high-temperature loading test is shortened.
[0118] In view of the above, the Sr content a is preferably in the
range of 0.ltoreq.a<0.5, the Ba content b is preferably in the
range of 0.ltoreq.b<0.5 and the Mg content c is preferably in
the range of 0.ltoreq.c<0.05. Meanwhile, the total of a, b, and
c is preferably in the range of 0.ltoreq.a+b+c<0.5. The Ti
content w is preferably in the range of0.ltoreq.w<0.6, the Mn
content x is preferably in the range of 0.ltoreq.x<0.05, the Ni
content y is preferably in the range of 0.ltoreq.y<0.05 and Hf
content z is preferably in the range of 0.ltoreq.z<0.3.
Meanwhile, the total of x and y is preferably in the range of
0.ltoreq.x+y.ltoreq.0.05 and the total of w, x, y, and z is
preferably in the range of 0.ltoreq.w+x+y+z<0.6.
[0119] As in the dielectric ceramic Sample 111 in Tables 10 and 14,
when subscript m is less than 0.98, dielectric loss is increased
and the average lifetime in the high-temperature loading lifetime
test is shortened. When subscript m is 1.03 or more as in the
dielectric ceramic Sample 112, sinterability is degraded
significantly. Subscript m is, therefore, preferably in the range
of 0.98.ltoreq.m<1.03.
[0120] When glass containing volatile components such as Li or B is
used as the additional compound oxide, the volatilization volume
and the volatilization timing varied with Samples. As a
consequence, some particles exhibited abnormal growth while others
exhibited no growth at all, causing increased fluctuation of
particle diameter. Accordingly, when the main-component of the
nonreducing dielectric ceramic complies with the above-described
ranges but the additional compound oxide contained Li-type glass or
Li--B type glass, the number of defective pieces in
moisture-resistance loading test increased as in the dielectric
ceramics Samples 113 and 114 in Table 10 and 14. Also, as in the
dielectric ceramic Sample 152 in Table 16 and 18, fluctuation in
breakdown-voltage was increased, thereby degrading the
reliability.
[0121] When the Si oxide, Mn oxide and Al oxide added to the powder
are not calcined in advance as in the nonreducing dielectric
ceramic Sample 115 in Tables 10 and 14, sinterability is degraded
and the number of defective pieces in the moisture-resistance
loading test is increased. When the compound oxide is not provided
with all of Si oxide, Mn oxide, and Al oxide, as in the nonreducing
dielectric ceramic Samples 116 to 118, sinterability is degraded
and the number of defective pieces in the moisture-resistance
loading test is increased.
[0122] In view of the above, the additional compound oxide is
preferably the type of compound oxide containing neither Li-type
nor Li--B type glass which satisfies the formula (Si,
T)O.sub.2--(Mn, M')O--Al.sub.2O.sub.3 wherein T is at least one
selected from the group consisting of Ti and Zr, M' is at least one
selected from the group consisting of Ni, Ba, Sr, Ca and Mg.
[0123] When the intensity ratio the maximum peak of a different
phase ("different phase" refers to every crystal phase which is not
the perovskite crystal phase) to the maximum peak characteristic of
perovskite crystal phase appearing at 2.theta.=25 to 35 degrees
exceeds about 5% in the CuK.alpha. X-ray diffraction analysis,
dielectric loss is undesirably increased and the average lifetime
in the high-temperature loading lifetime test is undesirably
shortened as shown by the dielectric ceramics Samples 119, 120,
123, 126, 128 and 130 in Table 14 and Sample 132 in Table 15. The
intensity of the maximum peak of the different phase relative to
the maximum peak of the perovskite crystal phase is preferably
about 5% or less.
[0124] As is apparent from the dielectric ceramics Samples 119,
120, 123, 126, 128, and 130 in Table 10, 12 and 14 and Sample 132
in Tables 11, 13 and 15, the following factors must be satisfied in
addition to satisfying the above-described composition ranges of
the main-component and complying with the types of the compound
oxide, in order to prevent the intensity of the maximum phase of
the different phase to the maximum peak of the perovskite crystal
phase from exceeding about 5%. First, an average particle diameter
of the main-component material is about 0.5 .mu.m or less after
milling and before calcining. Second, an A/B site ratio in the
main-component material is in the range of about 0.97 to 1.01
before calcining. Third, a calcination temperature is in the range
of about 1000 to 1300.degree. C.
[0125] FIG. 4 is an X-ray diffraction analysis chart of the
dielectric ceramic Sample 121 in which the intensity ratio of the
maximum peak of the different peak relative to the maximum peak of
the perovskite crystal phase is 0.5%. FIG. 5 is an X-ray
diffraction analysis chart of the dielectric ceramic Sample 119
having the intensity ratio of 5.5%. The asterisked peaks in the
charts are the peaks assigned to the perovskite crystal phase and
other peaks are peaks assigned to the different phases.
[0126] Preferably, a compound oxide represented by the formula
.alpha.(Si.sub.1-.mu.T.sub..mu.)O.sub.2--.beta.(Mn.sub.1-.nu.M'.sub..nu.)-
O--.gamma.Al.sub.2O.sub.3 (.alpha., .beta., and are molar percent,
T is at least one element selected from the group consisting of Ti
and Zr, and M' is at least one element selected from the group
consisting of Ni, Ba, Sr, Ca and Mg), wherein 0.ltoreq..mu.<0.5
and 0.ltoreq..nu.<0.5, and wherein the
(Si.sub.1-.mu.T.sub..mu.)O.sub.2 content, the
(Mn.sub.1-.nu.M'.sub..nu.)O content, and the Al.sub.2O.sub.3
content lie within the region surrounded in the ternary diagram in
FIG. 6 by points A (.alpha.=80.0, .beta.=20.0, .gamma.=0),
B(.alpha.=10.0, .beta.=90.0, .gamma.=0), C (.alpha.=10.0,
.beta.=20.0, .gamma.=70.0), D (.alpha.=30.0, .beta.=0,
.gamma.=70.0), and E (.alpha.=80.0, .beta.=0, .gamma.=20.0),
including the lines AE, BC and CD, but excluding the lines AB and
ED, is used as the compound oxide. The dielectric ceramics
containing such an oxide exhibits a significantly long lifetime of
400 hours or more in the high-temperature loading lifetime test as
shown by Samples 121, 122, 124, 125, 127, 129, 131, 133 to 135, 137
to 139, 141 to 143, and 145 to 148 in Tables 10, 11, 14 and 15.
[0127] When the raw materials are weighed to make the uncalcined
main-component material powder, the value of subscript k in the
formula:
(Ca.sub.1-a-b-cSr.sub.aBa.sub.bMg.sub.c).sub.k(Zr.sub.1-w-x-y-zTi.sub.wMn-
.sub.xNi.sub.yHf.sub.z)O.sub.3 is preferably in the range of
0.97.ltoreq.k.ltoreq.1.01 and more preferably in the range of
0.98.ltoreq.k.ltoreq.1.00. When k is less than 0.97, particle
growth of the raw materials are excessively promoted and an average
particle diameter after calcining is coarsened. As a consequence,
solid phase reaction is inhibited during sintering, the perovskite
crystal phase as the primary crystal phase is inhibited from being
synthesized and crystal phases not of the perovskite crystal phase
are generated. When k exceeds 1.01, formation of the perovskite
crystal phase as the primary crystal phase in the calcined material
powder is not satisfactory.
[0128] The uncalcined main-component material powder is preferably
milled to an average diameter of about 0.5 .mu.m or less, more
preferably, about 0.3 .mu.m or less, in a ball mill. When an
average diameter exceeds 0.5 .mu.m, the solid phase reaction during
the calcination is inhibited, the perovskite crystal phase as the
primary crystal phase is inhibited from being synthesized and
crystal phases not of the perovskite crystal phase are generated.
It is to be understood that no limit is imposed as to the lowest
value of an average particle diameter.
[0129] The material powder is preferably calcined at a temperature
in the range of about 1000 to 1300.degree. C. When the calcination
temperature is less than about 1000.degree. C., solid phase
reaction is inhibited and the perovskite crystal phase as the
primary crystal phase is inhibited from being synthesized.
Unreacted substances remain and cause the generation of crystal
phases not of perovskite crystal phase. When the calcination
temperature exceeds about 1300.degree. C., an average particle
diameter of the calcined material powder is excessively increased,
inhibiting solid phase reaction during the sintering process and
preventing the formation of the perovskite crystal phase as the
primary crystal phase.
[0130] It should be noted that although the thickness of the
sintered dielectric ceramic layer is 10 .mu.m in the Examples
above, the thickness can be further decreased to 5 .mu.m or less so
as to form a smaller high-capacitance monolithic ceramic capacitor.
In this case also, fluctuation in particle diameter is prevented
and sinterability is improved because of the above-described
compound oxide added to the material powder. The resulting
capacitor exhibits highly-reliable performance in high-temperature
loading test and moisture-resistance loading test and enjoys the
same advantages as that according to the Examples.
[0131] It should also be noted that in the Examples, the compound
oxides are primarily in an amorphous phase and "different phases"
refer to all the crystal phases not of the perovskite-structured
primary crystal phase, such as these generated by various additives
and by reaction between the compound oxide and the
main-component.
* * * * *