U.S. patent number RE29,484 [Application Number 05/729,290] was granted by the patent office on 1977-11-29 for barium titanate base ceramic composition having a high dielectric constant.
This patent grant is currently assigned to Nippon Electric Company, Limited. Invention is credited to Tomeji Ohno, Norio Tsubouchi, Kazuaki Utsumi.
United States Patent |
RE29,484 |
Utsumi , et al. |
November 29, 1977 |
Barium titanate base ceramic composition having a high dielectric
constant
Abstract
A ceramic composition having a high dielectric constant which
has good stability with temperature variation and the passage of
time includes BaTiO.sub.3 in which the molecular ratio of Ba to Ti
ranges from about 0.9 to 1.1 as the basic constituent and about 0.1
to 10 mol % of at least one compound selected from the group of
Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % of
at least one compound selected from the group consisting of
In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO and
NiO as sub constituents.
Inventors: |
Utsumi; Kazuaki (Tokyo,
JA), Tsubouchi; Norio (Tokyo, JA), Ohno;
Tomeji (Tokyo, JA) |
Assignee: |
Nippon Electric Company,
Limited (Tokyo, JA)
|
Family
ID: |
27548913 |
Appl.
No.: |
05/729,290 |
Filed: |
October 4, 1976 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
453998 |
Mar 22, 1974 |
03912527 |
Oct 14, 1975 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Mar 24, 1973 [JA] |
|
|
49-33896 |
May 9, 1973 [JA] |
|
|
48-51996 |
Feb 20, 1974 [JA] |
|
|
49-20303 |
Feb 22, 1974 [JA] |
|
|
49-21225 |
|
Current U.S.
Class: |
501/139;
252/520.21; 501/138 |
Current CPC
Class: |
C04B
35/46 (20130101); C04B 35/4682 (20130101); C04B
35/48 (20130101); C04B 35/50 (20130101); C04B
35/51 (20130101); H01B 3/12 (20130101) |
Current International
Class: |
C04B
35/462 (20060101); C04B 35/48 (20060101); C04B
35/51 (20060101); C04B 35/50 (20060101); C04B
35/468 (20060101); C04B 35/46 (20060101); H01B
3/12 (20060101); C04B 035/46 (); H01B 001/08 () |
Field of
Search: |
;106/73.31,73.32,DIG.5
;252/520 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Three -Step Positive Temperature Coefficient of Resistivity...,"
Kuwabara et al., CA 79:71231t (1973)..
|
Primary Examiner: Wyman; Daniel E.
Assistant Examiner: Waltz; Thomas A.
Attorney, Agent or Firm: Hopgood, Calimafde, Kalil,
Blaustein & Lieberman
Claims
We claim:
1. A dielectric ceramic composition having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 0.1 to
10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5,
and about 0.01 to 15 mol % of at least one of the compounds
In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3.
2. A dielectric ceramic composition having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3, 0.1 to
10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5,
about 0.01 to 15 mol % of at least one of the compounds In.sub.2
O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3, and about 0.01 to
10 mol % of Al.sub.2 O.sub.3.
3. A dielectric ceramic composition, having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a
basic constituent, 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 as a sub
constituent, and 0.05 to 5.0 mol % of at least one of the compounds
In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another
sub constituent.
4. A dielectric ceramic composition, having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a
basic constituent, 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 as one sub
constituent, 0.05 to 5.0 mol % of at least one of the compounds
In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as a
second sub constituent and 0.5 to 5.0 mol % of Al.sub.2 O.sub.3 as
a third sub constituent, the total amount of said sub constituents
being within a range of 1.05 to 10 mol %.
5. A dielectric ceramic composition, having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a
basic constituent, 0.5 to 5.0 mol % of Ta.sub.2 O.sub.5 as a sub
constituent, and 0.05 to 5.0 mol % of at least one of the compounds
In.sub.2 O.sub.5, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another
sub constituent.
6. A dielectric ceramic composition, having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a
basic constituent, 0.5 to 5.0 mol % of Ta.sub.2 O.sub.5 as a sub
constituent, 0.05 to 5.0 mol % of at least one of the compounds
In.sub.2 O.sub.5, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another
sub constituent and 0.5 to 5.0 mol % of Al.sub.2 O.sub.3 as a
further sub constituent.
7. A dielectric ceramic composition, having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of non-stoichometric
BaTiO.sub.3 in which the molecular ratio of Ba to Ti lies within
the range of approximately 0.9 to 1.1, 0.1 to 10 mol % of at least
one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 ; and 0.01 to 15 mol %
of at least one of the compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3
and Tl.sub.2 O.sub.3.
8. A dielectric ceramic composition having a high dielectric
constant, consisting of 77.5 to 99.79 mol % of non-stoichometric
BaTiO.sub.3 in which the molecular ratio of Ba to Ti lies within
the range of approximately 0.9 to 1.1, 0.1 to 10 mol % of at least
one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 ; 0.01 to 15 mol % of
at least one of the compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3
and Tl.sub.2 O.sub.3 ; and further including 0.01 to 10 mol % of
Al.sub.2 O.sub.3.
Description
BACKGROUND OF THE INVENTION
The present invention relates to ceramic compositions containing
BaTiO.sub.3 as the basic composition, and particularly to such
ceramic compositions having a high dielectric constant and in which
the dielectric constant remains substantially stable despite
temperature variation and the passage of time.
Ceramic compositions having the above described properties are
suitable for use in various electronic devices, such as for
instance ceramic capacitors. In order to be practical for use in
ceramic capacitors, it is desirable that a material have a
dielectric constant (.epsilon.) of up to 2,000. The dielectric
constant should remain relatively stable over a wide temperature
range, for example, from minus 55.degree. C to plus 125.degree. C
and should have good stability over the passage of time. It is also
desirable that the dielectric loss (tan.delta.) of the material be
low.
In order to fulfill these requirements, a variety of compositions
have heretofore been prepared. Most of these prior art
compositions, however, have only had a dielectric constant which
was stable with reference to either temperature or time. Moreover,
the temperature range of good dielectric constant stability has
been very narrow, so that practical applications have been quite
limited.
It has been recently found that ceramic compositions containing
barium titanate (BaTiO.sub.3) as the basic component and Ce, La and
Bi as additives have a good temperature stability of their
dielectric constant over a temperature range of -55.degree. C to
+125.degree. C. The stability of the dielectric constant of such
materials is also good with respect to time. This fact is reported
in detail, for example, by Johannes Just, in an article entitled
"Eigenschaften von hochtemperaturbestandigen Sonderkeramiken mit
hoher Dielektrizitatskonstante," which appeared in `Technische
Mitteilungen AEG-Telefunken Gesellschaft`, Vol. 60, No. 2, pages
125-126 (1970). However, in compositions of the type described in
this article having dielectric constants which have good stability
with respect to time and temperature, the dielectric constant is
degraded to below 1,000 in value. Moreover, since Bi which has a
high vapor pressure and is very reactive is contained in these
compositions, it is difficult to use them in the manufacture of
ceramics. When for instance these compositions are used to
manufacture a laminated ceramic capacitor, internal electrodes made
of platinum or palladium are noticeably corroded.
An object of the present invention is to eliminate the
disadvantages mentioned above.
Another object of the present invention is to provide ceramic
compositions which have a high dielectric constant and exhibit good
temperature stability over a wide temperature range together with
good time stability.
A further object of the present invention is to provide ceramic
compositions which contain BaTiO.sub.3 as a basic composition but
contain no Bi, so that capacitor manufacture using these
compositions is facilitated and these compositions provide an
optimum material for the manufacture of, for instance, laminated
ceramic capacitors.
SUMMARY OF THE INVENTION
The ceramic compositions of the present invention contain
BaTiO.sub.3 as the basic constituent, in which the molecular ratio
of Ba to Ti is within the range from about 0.9 to 1.1. These
compositions further contain about 0.1 to 10 mol % of at least one
compound selected from the group consisting of Nb.sub.2 O.sub.5 and
Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % of at least one
compound selected from the group consisting of In.sub.2 O.sub.3,
Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO, and NiO as sub
constituents. If desired, compositions within the above composition
ranges may also contain about 0.01 to 10 mol % of Al.sub.2 O.sub.3
as another sub constituent to provide even greater improvement in
both the temperature stability and the time stability of the
dielectric constant.
DESCRIPTION OF THE INVENTION
The ceramic compositions of the present invention have BaTiO.sub.3
as their basic constituent. The BaTiO.sub.3 is manufactured so that
the molecular ratio of Ba to Ti is within the range of about 0.9 to
1.1. In addition, these ceramic compositions contain about 0.1 to
10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5
and about 0.01 to 15 mol % of at least one of In.sub.2 O.sub.3,
Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, Zno, and NiO as sub
constituents. These compositions may also contain about 0.01 to 10
mol % of Al.sub.2 O.sub.3 as a further sub constituent.
If the content of Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5 is less
than 0.1 mol % in these ceramic compositions, tan .delta. will
become large. While, if the content of Nb.sub.2 O.sub.5 and/or
Ta.sub.2 O.sub.5 is more than 10 mol % or if the content of one or
more of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO,
ZnO and NiO is less than 0.01 mol %, the temperature stability of
the dielectric constant will be .[.degreaded.].
.Iadd.degraded.Iaddend.. If the content of one or more of In.sub.2
O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO and NiO is
more than 15 mol % or if the content of Al.sub.2 O.sub.3 is more
than 10 mol %, the value of the dielectric constant will become
low, e.g., below 1,500.
According to a first example of the present invention, a ceramic
composition is made containing BaTiO.sub.3, about 0.1 to 10 mol %
and preferably about 0.5 to 5.0 mol %, of Nb.sub.2 O.sub.5 and/or
Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % and preferably about
0.05 to 5.0 mol % of at least one of In.sub.2 O.sub.3, Ga.sub.2
O.sub.3, and Tl.sub.2 O.sub.3. Less than 10 mol %, and preferably
about 0.5 to 5.0 mol % Al.sub.2 O.sub.3 may be added to the
composition. It is preferable that the total amount of sub
constituents in the composition be about 1.05 to 10 mol %.
According to a second example of the present invention, a ceramic
composition contains BaTiO.sub.3, about 0.1 to 10 mol % and
preferably about 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 and/or
Ta.sub.2 O.sub.5, about 0.001 to 10 mol % and preferably about 0.5
to 5.0 mol % of MgO, ZnO, or NiO, and about 0.1 to 10 mol % and
preferably about 0.5 to 5.0 mol % of Al.sub.2 O.sub.3. This
composition may also contain at least one of TiO.sub.2, SiO.sub.2,
SnO.sub.2, GeO.sub.2 and ZrO.sub.2 in an amount of about 0.01 to 10
mol % and preferably about 0.1 to 5.0 mol %. It is preferable that
the total amount of sub constituents in the composition be about
1.6 to 10.0 mol %.
The ceramic compositions of the present invention have a high
dielectric constant which is for example in the range of 1,500 to
3,500. The dielectric constant of these compositions has good
stability over a wide temperature range, varying only in the range
of +15% to -20% over a temperature range of -55.degree. C to
+125.degree. C. The dielectric constant of these compositions also
has good stability with respect to time.
As starting materials for making the basic constituent of the
ceramic compositions of the present invention, BaCO.sub.3 and
TiO.sub.2 powders of at least 99% purity were used. Powders of
Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, In.sub.2 O.sub.3, Ga.sub.2
O.sub.3, Tl.sub.2 O.sub.3, Al.sub.2 O.sub.3, MgO, ZnO, NiO,
TiO.sub.2, SnO.sub.2, SiO.sub.2, GeO.sub.2, and ZrO.sub.2 of at
least 99% purity were employed as the sub constituents. The
BaCO.sub.3 and TiO.sub.2 were added together in equal mols, and
were mixed by means of a ball mill. This mixture was thereafter
pre-sintered at 1,000.degree. to 1,200.degree. C. It was determined
by the powder X-ray diffraction method that the pre-sintering
caused the powder to be thoroughly transformed into BaTiO.sub.3.
The pre-sintered BaTiO.sub.3 powder and the starting materials of
subconstituents were weighed to obtain the necessary quantities,
and were mixed by means of a ball mill. After filtration and
drying, the mixture was pressure-molded into discs having a
diameter of 16mm. These discs were sintered then at 1,300.degree.
to 1,450.degree. C for 1 hour.
Silver electrodes were then provided on both the principal surfaces
of the resultant ceramic discs by burning at 600.degree. C. The
dielectric constant (.epsilon.) and the dielectric loss
(tan.delta.) were then measured with a capacitance bridge by
applying an alternating current of 1 KHz to the ceramic discs at a
temperature of 20.degree. C. The temperature stability of the
dielectric constant was estimated by measuring it at various
temperatures within the range of -55.degree. C and +125.degree. C
and calculating the rate of temperature variation of the dielectric
constant with reference to the value of the dielectric constant at
+20.degree. C. The temperature stability of the dielectric constant
can then be represented by: ##EQU1## where .epsilon..sub.20 denotes
the value of .epsilon. at +20.degree. C, while .epsilon..sub.max
and .epsilon..sub.min respectively denote the maximum and the
minimum values of the dielectric constant within the temperature
range of -55.degree. C to +125.degree. C.
In order to estimate the time stability of the dielectric constant,
the value of the dielectric constant was measured several times
over a period of time from 12 hours to 1,000 hours after the
provision of the silver electrodes by burning. The rate of
variation (A.sub..epsilon.) of the dielectric constant with respect
to time was calculated by the following equation: ##EQU2## where t:
elapsed time,
.epsilon..sub.t0 : the value of .epsilon. at a time 12 hours after
the provision of the electrodes by burning, and .epsilon..sub.t :
the value of .epsilon. after an elapsed time of t hours.
Typical examples of the results obtained are listed in Tables 1, 2
and 3. Specimens shown with an asterisk in the tables are
compositions outside the scope of the present invention.
Table 1
__________________________________________________________________________
rate rate of temp. of time variation variation Spec- tan .delta. of
.epsilon. (%) of .epsilon. [A] imen Composition (mol %) .epsilon.
(%) [-55.degree. C (%/ No. BaTiO.sub.3 Nb.sub.2 O.sub.5 Al.sub.2
O.sub.3 Other Subconstituents [20.degree. C] [20.degree. C] to
+125.degree. C] decade)
__________________________________________________________________________
1* 95 2.5 2.5 -- -- -- -- 3130 6.40 +4 .about. -42 -1.5 2* 96 2.5
1.5 -- -- -- -- 2310 0.78 +19 .about. -30 -1.0 3* 96.5 1.5 2.0 --
-- -- -- 2770 0.36 0 .about. -40 -0.8 4 96 1.5 2.49 In.sub.2
O.sub.3 0.01 -- -- 2540 0.45 0 .about. -19 -0.8 5 96 1.5 2.40 "
0.10 -- -- 2450 0.40 0 .about. -16 -1.2 6 96 1.5 2.25 " 0.25 -- --
2040 0.35 +1 .about. -8 -1.2 7 96 1.5 2.00 " 0.50 -- -- 2270 0.55
+15 .about. -10 -1.0 8 96 1.5 1.50 " 1.00 -- -- 1820 0.55 +15
.about. -10 -1.5 9 97 1.0 -- " 2.0 -- -- 2620 0.40 0 .about. -16
-1.1 10 99.79 0.1 0.1 " 0.1 -- -- 2510 1.92 +7 .about. -11 -1.8 11
84.8 10.0 5.0 " 0.2 -- -- 1980 0.98 +10 .about. -6 -0.7 12 77.5 5.0
2.5 " 15.0 -- -- 1750 0.48 +9 .about. -19 -0.8 13 92.5 2.0 5.0 "
0.5 -- -- 1510 0.36 +8 .about. -6 -1.3 14 96.7 2.0 1.0 " 0.3 -- --
3000 0.33 +4 .about. -9 -1.2 15 97.8 1.5 0.5 " 0.2 -- -- 3100 0.41
+8 .about. -10 -1.0 16 78.0 7.0 -- Ga.sub.2 O.sub.3 15.0 -- -- 1770
0.86 +12 .about. -18 -1.0 17 97.2 1.5 1.0 " 0.3 - - 2200 0.42 +4
.about. -10 -1.2 18 97.2 1.5 1.2 " 0.1 -- -- 2460 0.67 0 .about.
-17 -0.8 19 78.0 7.0 -- Tl.sub.2 O.sub.3 15.0 -- -- 1650 0.79 +11
.about. -18 -0.9 20 97.2 1.5 1.0 " 0.3 -- -- 2110 0.51 +8 .about.
-6 -1.3 21 97.2 1.5 1.2 " 0.1 -- -- 2300 0.39 0 .about. -13 -1.0 22
94.0 2.5 3.0 MgO 0.5 -- -- 2500 0.51 +14 .about. -12 -1.5 23 79.8
0.1 0.1 " 10.00 TiO.sub.2 10.0 3000 2.10 +5 .about. -15 -0.7 24
83.0 10.0 5.0 " 1.0 " 1.0 2530 1.00 +13 .about. -14 -1.0 25 83.0
5.0 10.0 " 1.0 " 1.0 2100 0.89 +12 .about. -13 -1.2 26 97.98 1.0
1.0 " 0.01 " 0.01 2300 0.43 +13 .about. -15 -1.5 27 95.0 2.5 1.5 "
0.5 " 0.5 1860 0.45 +10 .about. -13 -1.5 28 95.0 2.0 2.0 " 0.5 "
0.5 2560 0.50 +12 .about. -9 -1.2 29 94.5 1.0 1.5 " 1.5 " 1.5 1820
0.60 +17 .about. -12 -1.0 30 97.99 1.0 1.0 ZnO 0.01 -- -- 2400 0.83
+4 .about. -13 -1.3 31 93.0 1.0 1.0 ZnO 2.5 TiO.sub.2 2.5 2750 0.90
+6 .about. -13 -1.0 32 92.0 1.0 1.0 " 3.0 " 3.0 2530 1.10 +5
.about. -12 -2.0 33 78.0 1.0 1.0 " 10.0 " 10.0 1650 0.53 +7 .about.
-11 -1.0 34 93.5 2.5 2.0 " 1.0 SnO.sub.2 1.0 2300 0.73 +9 .about.
-10 -1.5 35 78.0 1.0 1.0 " 10.0 " 10.0 1700 0.62 +3 .about. -7 -1.4
36 95.5 1.0 1.5 " 1.0 SiO.sub.2 1.0 2400 0.65 +7 .about. -8 -0.9 37
78.0 1.0 1.0 " 10.0 " 10.0 1730 0.55 +9 .about. -4 -0.7 38 95.5 1.0
1.5 " 1.0 GeO.sub.2 1.0 2630 0.43 +10 .about. -7 -1.3 39 78.0 1.0
1.0 " 10.0 " 10.0 1560 0.41 +3 .about. -6 -2.0 40 94.5 2.0 1.5 "
1.0 ZrO.sub.2 1.0 2120 0.81 +4 .about. -10 -1.7 41 78.0 1.0 1.0 "
10.0 " 10.0 1770 0.91 +7 .about. -9 -2.0 42 97.0 1.0 1.5 NiO 0.5 --
-- 2440 0.83 +3 .about. -11 -0.7 43 95.98 2.0 2.0 " 0.01 TiO.sub.2
0.01 2510 0.75 +4 .about. -9 -1.2 44 95.0 1.5 1.5 " 1.0 " 1.0 2320
0.91 +7 .about. -7 -1.3 45 78.0 1.0 1.0 " 10.0 " 10.0 1600 1.01 +11
.about. -4 -1.1 46 97.99 1.0 1.0 In.sub.2 O.sub.3 0.005 Ga.sub.2
O.sub.3 0.005 2830
0.35 +1 .about. -13 -0.7 47 97.90 1.0 1.0 " 0.05 " 0.05 2540 0.41
+3 .about. -11 -1.1 48 97.75 1.0 1.0 " 0.125 " 0.125 2500 0.35 +5
.about. -10 -1.2 49 97.50 1.0 1.0 " 0.25 " 0.25 2380 0.51 +8
.about. -9 -0.9 50 97.00 1.0 1.0 " 0.5 " 0.5 2320 0.72 + 10 .about.
-5 -0.8 51 97.00 1.0 -- " 1.0 " 1.0 2330 0.63 +5 .about. -8 -1.0 52
99.79 0.01 0.1 " 0.05 " 0.05 2960 0.91 +4 .about. -10 -1.3 53 88.80
10.0 1.0 " 0.1 " 0.1 1820 0.21 +1 .about. -13 -0.7 54 83.90 1.0 0.1
" 7.5 " 7.5 1550 0.32 +7 .about. -11 -0.9 55 88.50 1.0 10.0 " 0.25
" 0.25 1920 0.43 +5 .about. -10 -0.8 56 97.70 1.5 0.5 " 0.15 " 0.15
2480 0.38 +8 .about. -7 -0.9 57 84.00 1.0 -- -- Tl.sub.2 O.sub.3
7.5 " 7.5 1630 0.55 +3 .about. -14 -1.1 58 97.20 1.5 1.0 " 0.15 "
0.15 2210 0.61 +9 .about. -7 -1.2 59 97.29 1.5 1.2 " 0.005 " 0.005
2350 0.48 +2 .about. -12 -0.7 60 84.00 1.0 -- " 7.5 In.sub.2
O.sub.3 7.5 1610 0.65 +5 .about. -13 -0.9 61 97.20 1.5 1.0 " 0.15 "
0.15 2280 0.54 +7 .about. -9 -0.8 62 97.29 1.5 1.2 Tl.sub.2 O.sub.3
0.005 In.sub.2 O.sub.3 0.005 2310 0.37 +4 .about. -9 -1.1 63 92.00
1.0 -- " 2.0 " 3.0 2120 0.71 0 .about. -15 -1.0 Ga.sub.2 O.sub.3
2.0 64 97.20 1.5 1.0 Tl.sub.2 O.sub.3 0.1 " 0.03 2430 0.62 +11
.about. -5 -1.0 Ga.sub.2 O.sub.3 0.17 65 97.29 1.5 1.2 Tl.sub.2
O.sub.3 0.002 " 0.003 2510 0.53 +3 .about. -7 -0.9 Ga.sub.2 O.sub.3
0.005
__________________________________________________________________________
Table 2
__________________________________________________________________________
rate rate of of temp. time vari- variation ation of tan .delta. of
.epsilon. (%) .epsilon.[A.sub.. epsilon. ] Specimen Composition
(mol %) .epsilon. (%) [-55.degree. C (%/ No. BaTiO.sub.3 Ta.sub.2
O.sub.5 Al.sub.2 O.sub.3 In.sub.2 O.sub.3 Ga.sub.2 O.sub.3 Tl.sub.2
O.sub.3 [20.degree. C] [20.degree. C] to +125.degree. C] decade)
__________________________________________________________________________
66* 99.0 1.0 -- -- -- -- 2800 4.8 +30 .about. -40 -3.0 67 98.99 1.0
0.01 -- -- -- 2720 0.64 0 .about. -17 -1.0 68 98.0 1.0 1.0 -- -- --
2540 0.35 0 .about. -20 -1.6 69 84.0 1.0 1.5 -- -- -- 1500 0.82 +11
.about. -4 -1.8 70 98.49 1.5 -- 0.01 -- -- 2380 0.67 0 .about. -13
-1.5 71 97.5 1.5 -- 1.0 -- -- 2300 0.71 +4 .about. -3 -1.5 72 84.0
1.0 -- 1.5 -- -- 1510 0.73 +3 .about. -6 -1.7 73 98.49 1.5 -- --
0.01 -- 2740 0.61 +4 .about. -8 -1.4 74 98.0 1.0 -- -- 1.0 -- 3190
0.65 +11 .about. -4 -2.0 75 84.0 1.0 -- -- 1.5 -- 1500 0.79 +9
.about. -3 -2.1 76 98.49 1.5 -- -- -- 0.01 2710 0.84 +5 .about. -9
-0.9 77 97.5 1.5 -- -- -- 1.0 2650 0.71 +9 .about. -10 -1.1 78 84.0
1.0 -- -- -- 1.5 1530 0.62 +10 .about. -12 -1.3 79 98.87 0.1 1.0
0.03 -- -- 2630 0.73 +11 .about. -8 -0.8 80 97.5 1.0 1.0 0.5 -- --
2410 0.52 +8 .about. -9 -1.1 81 96.47 1.5 2.0 0.03 -- -- 2260 0.43
+7 .about. -7 -1.5 82 93.9 5.0 1.0 0.1 -- -- 2080 0.44 +3 .about.
-12 -1.6 83 88.9 10.0 1.0 0.1 -- -- 1610 0.76 +0 .about. -15 -1.8
84 98.0 1.0 0.5 -- 0.5 -- 2580 0.71 +0 .about. -14 -2.0 85 97.5 1.0
1.0 -- -- 0.5 2540 0.65 +0 .about. -17 -2.1 86 97.5 1.0 -- -- 1.0
0.5 2420 0.56 +3 .about. -13 -1.3 87 98.0 1.0 -- 0.5 -- 0.5 2680
0.81 +1 .about. -11 -1.2 88 97.5 1.0 -- 0.5 1.0 -- 2370 0.77 +2
.about. -11 -1.5 89 97.47 1.0 -- 0.03 1.0 0.5 2330 0.69 +5 .about.
-9 -1.7 90 97.97 1.0 0.5 -- 0.5 0.03 2410 0.53 +4 .about. -12 -1.9
91 97.47 1.0 1.0 0.03 -- 0.5 2330 0.55 +7 .about. -10 -1.1 92 95.95
1.5 1.5 0.05 1.0 -- 2150 0.62 +6 .about. -9 -0.8 93 96.3 1.5 0.5
0.1 1.5 0.1 2470 0.71 +5 .about. -5 -
__________________________________________________________________________
0.6
Table 3
__________________________________________________________________________
rate of rate of tan .delta. temp. variation time variation Specimen
Composition (mol %) .epsilon. (%) of .epsilon. (%) of .epsilon.
[A.sub..epsilon. ] No. BaTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2
O.sub.5 Al.sub.2 O.sub.3 In.sub.2 O.sub.3 [20.degree. C]
[20.degree. C] [-55.degree. C to +125.degree. C] (%/decade)
__________________________________________________________________________
94 96.0 0.5 1.0 2.25 0.25 2130 0.38 +2 .about. -7 -1.0 95 97.5 0.5
0.5 1.0 0.5 2380 0.45 +6 .about. -7 -0.9 96 96.47 1.0 0.5 2.0 0.03
2280 0.45 +3 .about. -7 -0.8
__________________________________________________________________________
The specimens numbered 1, 2, 3 and 66 indicate results for
compositions outside the scope of the present invention for
comparison. Results for specimens 1, 2, 3 and 66 show wide
percentage variation of the dielectric constant of the test
compositions within the range of temperatures tested. By contrast
from Tables 1 to 3, the example specimens numbered 4 through 65 and
67 through 96 have compositions within the scope of the present
invention, and these compositions show a relatively smaller
variation in dielectric constant with variation in temperature. The
rate of variation of dielectric constant with time of these
compositions is also small. Moreover, the compositions of the
present invention have dielectric constants of sufficiently large
values and superior values of dielectric loss (tan.delta.).
While almost all of the foregoing examples have been described as
employing, as the basic constituent, BaTiO.sub.3 in which Ba and Ti
are used in equimolecular amounts, similar effects can be achieved
utilizing BaTiO.sub.3 in which the molecular ratio of Ba to Ti
(Ba/Ti) ranges from about 0.9 to 1.1, as shown by the results for
specimens 50, 56, 71 and 80 in Tables 1 and 2. The specimens
numbered 50 and 71 indicate results for compositions in which the
molecular ratio of Ba to Ti (Ba/Ti) is 0.9. While, the specimens 56
and 80 indicate results for compositions in which the molecular
ratio of Ba to Ti is 1.1.
* * * * *