U.S. patent application number 09/775493 was filed with the patent office on 2001-09-27 for capacitor.
Invention is credited to Naito, Kazumi.
Application Number | 20010024351 09/775493 |
Document ID | / |
Family ID | 12725261 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024351 |
Kind Code |
A1 |
Naito, Kazumi |
September 27, 2001 |
Capacitor
Abstract
In a capacitor comprising a pair of electrodes and a dielectric
substance intervening between the two electrodes, one of the
electrodes is composed of sintered niobium nitride. Preferably, the
dielectric substance is composed of niobium oxide and the electrode
other than the electrode composed of sintered niobium nitride is
composed of an ingredient selected from electrolytes, organic
semiconductors and inorganic semiconductors. This capacitor has
good environmental stability and good leak current
characteristics.
Inventors: |
Naito, Kazumi; (Chiba-shi,
JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS, PLLC
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037-3202
US
|
Family ID: |
12725261 |
Appl. No.: |
09/775493 |
Filed: |
February 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09775493 |
Feb 5, 2001 |
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09620898 |
Jul 20, 2000 |
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09620898 |
Jul 20, 2000 |
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09171902 |
Oct 28, 1998 |
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6115235 |
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Current U.S.
Class: |
361/303 |
Current CPC
Class: |
H01G 9/042 20130101 |
Class at
Publication: |
361/303 |
International
Class: |
H01G 004/005 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 1997 |
JP |
9/45650 |
Claims
1. A capacitor comprising a pair of electrodes and a dielectric
substance intervening between the electrodes, characterized in that
one of the electrodes is composed of sintered niobium nitride.
2. The capacitor according to claim 1, wherein the content of bound
nitrogen in the sintered niobium nitride is in the range of 10 to
200,000 ppm by weight.
3. The capacitor according to claim 1 or 2, wherein the dielectric
substance is composed of niobium oxide.
4. The capacitor according to claim 3, wherein the dielectric
substance composed of niobium oxide is formed on the electrode
composed of sintered niobium nitride by conversion-treating the
electrode composed of sintered niobium nitride in an electrolyte,
or subjecting a niobium-containing complex to hydrolysis and/or
pyrolysis on the electrode composed of sintered niobium
nitride.
5. The capacitor according to any of claims 1 to 4, wherein the
electrode other than the electrode composed of sintered niobium
nitride is at least one ingredient selected from electrolytes,
organic semiconductors and inorganic semiconductors.
6. The capacitor according to any of claims 1 to 4, wherein the
electrode other than the electrode composed of sintered niobium
nitride is at least one ingredient selected from organic
semiconductors and inorganic semiconductors, which have an
electrical conductivity of 10.sup.-2 S.multidot.cm.sup.-1 to
10.sup.3 S.multidot.cm.sup.-1.
Description
TECHNICAL FIELD
[0001] This invention relates to a novel capacitor. More
particularly, it relates to a capacitor which is inexpensive and
exhibits good leak current characteristics, and E capacitor which
has a large capacitance, especially a large capacitance per unit
weight at a high frequency, and exhibits good leak
characteristics.
BACKGROUND ART
[0002] As an electrode of a capacitor made of a sintered metal,
those which are composed of sintered aluminum, tantalum and alloys
thereof are known. These capacitors have widely used in various
fields. For example, for a capacitor used in a Smoothing circuit
for obtaining a direct current from an alternating current, it is
desired that the capacitor possesses a low impedance and a large
capacitance at a high frequency for suppressing the occurrence of
spike-shaped voltage and enhancing the efficiency of conversion to
a direct current.
[0003] The above-mentioned sintered metals used as a capacitor
electrode have problems. Namely, sintered aluminum has poor
environmental characteristics such as moisture resistance and
chemical characteristics, and sintered tantalum is expensive.
Sintered niobium is also known as a material used for a capacitor
electrode, and not possessing the problems encountered with
sintered aluminum and tantalum, but, it has another problem that
oxygen adsorbed on its surface influences dielectrics as mentioned
below, and thus, the leak current characteristics are not
satisfactory and it is of poor practical use.
[0004] To provide a capacitor used in a smoothing circuit and
having an enhanced capacitance at a high frequency, the volume of a
sintered metal substrate made of, for example, tantalum or
aluminum, should be increased. The increase in volume of the
sintered metal substrate is inconsistent with a requirement of
miniaturization of a capacitor. Among others, tantalum gives a
relatively satisfactory for the requirements of an enhanced
capacitance at a high frequency and a miniaturization of a
capacitor, but, it is still not completely satisfactory for these
requirements. Usually a tantalurn oxide is used as a dielectric
substance for a capacitor with an electrode composed of sintered
tantalum bodies. However, if a material having a dielectric
constant larger than that of tantalum oxide is used as a dielectric
substance, the capacitor can be more miniaturized. As examples of
the material having a large dielectric constant, there can be
mentioned titanium oxide and niobium oxide. But, these materials
exhibit poor leak current (hereinafter abbreviated to "LC")
characteristics.
DISCLOSURE OF INVENTION
[0005] The inventors have found, first, that sintered bodies of
niobium nitride are advantageous in that the amount of oxygen
deposited on the surface thereof is minor and the leak current
characteristics of the capacitor are satisfactory, and secondly,
that the above-mentioned problem as for LC characteristics of a
capacitor with niobium oxide dielectrics is due to the fact that
oxygen deposited on the surface of sintered bodies influences the
dielectric substance. Based on these findings, the inventors have
completed the present invention.
[0006] The inventors have further found that, if the electrode
other than the electrode composed of sintered niobium nitride
bodies is made of at least one compound selected from organic
semiconductors and inorganic semiconductors, which do not have a
capability of supplying oxygen to an undue extent, a capacitor
having a large capacitance at a high frequency can be obtained.
Further, if, as the organic semiconductor or the inorganic
semiconductor, those which have an electrical conductivity of
10.sup.-2 S.multidot.cm.sup.1 to 10.sup.3 S.multidot.cm.sup.-1 are
used, a capacitor having a more reduced impedance can be
obtained.
[0007] Thus, in accordance with the present invention, there is
provided a capacitor comprising a pair of electrodes and a
dielectric substance intervening between the electrodes,
characterized in that one of the electrodes is composed of sintered
niobium nitride.
[0008] The dielectric substance of the above-mentioned capacitor is
preferably made of niobium oxide, more preferably made of niobium
oxide prepared by electrolytic oxidation of the sintered niobium
nitride. The other of the two electrodes is preferably made of at
least one ingredient selected from electrolytes, organic
semiconductors and inorganic semi-conductors, more preferably at
least one ingredient selected from organic semiconductors and
inorganic conductors, which have an electrical conductivity of from
10.sup.-2 S.multidot.cm.sup.-1 to 10.sup.3
S.multidot.cm.sup.-1.
BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1 is a partially cutaway view in perspective
specifically illustrating one example of the capacitor of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0010] The niobium nitride constituting one of the electrodes in
the capacitor of the invention is made by partially nitrifying
metallic niobium. For example, niobium nitride of a powdery form is
made by nitrifying the surfaces of particles of powdery niobium in
a nitrogen gas atmosphere. In this instance, the amount of nitrogen
bound to the niobium is in the range of from 10 to 200,000 ppm by
weight, preferably 100 to 50,000 ppm by weight. For nitrifying
niobium into niobium nitride having the desired nitrogen content,
the temperature employed is not higher than 2,000.degree. C. and
the time employed is in several tens of hours. Generally, as the
temperature for nitrification becomes high, the particle surfaces
of powdery niobium are nitrified in a shorter time. Even at room
temperature, when powdery niobium is fluidized for several tens of
hours, powdery niobium nitride containing several hundreds ppm of
nitrogen is obtained.
[0011] The thus-obtained powdery niobium nitride has a shape
approximately similar to that of the powdery niobium used as the
raw material. In one example, if a powdery niobium mass obtained by
pulverizing a niobium lump is used as a raw material, powdery
niobium nitride having various shapes which are peculiar to
pulverized mass is obtained. In another example, if powdery niobium
in the form of a secondary particle is used, which is prepared by
reducing potassium fluoroniobate to give a finely divided
particles, and granulating the finely divided particles into
secondary particles, then, powdery niobium nitride similar to the
secondary particles is obtained. Further, for example, if powdery
niobium having an average particle diameter of from 0.5 .mu.m to
100 .mu.m is used, powdery niobium nitride having a similar average
particle diameter is obtained.
[0012] The sintered niobium nitride is obtained by sintering, for
example, powdery niobium nitride at a high temperature in vacuo. In
one example, powdery niobium nitride is press-molded and then the
molded product is allowed to stand at a temperature of 1,000 to
2,000.degree. C. and a pressure of 10.sup.-1 to 10.sup.-6 Torr for
several minutes to several hours to give a sintered niobium
nitride. If the degree of vacuum is insufficient at sintering, air
is entrapped in the powdery material during sintering, oxidation
occurs simultaneously with nitrification with the result that the
capacitor with the niobium nitride electrode has a poor
performance. Generally a suitable sintering temperature varies
depending upon the particle diameter of the powdery niobium
nitride, and, the smaller the particle diameter, the lower the
sintering temperature.
[0013] As the dielectric substance used in the capacitor of the
invention, there can be mentioned, for example, tantalum oxide,
niobium oxide, polymeric substances and ceramic compounds. When
tantalum oxide is used as a dielectric substance, the tantalum
oxide can be prepared by depositing a tantalum-containing complex
such as, for example, an alkoxy complex or an acetylacetonato
complex on an electrode, and then, subjecting the deposit to
hydrolysis and/or pyrolysis. When niobium oxide is used as a
dielectric substance, the niobium oxide can be prepared by
chemically converting a niobium nitride electrode into niobium
oxide in an electrolyte, or by depositing a niobium-containing
complex such as, for example, an alkoxy complex or an
acetylacetonato complex on an electrode, and then, subjecting the
deposit to hydrolysis and/or pyrolysis. Thus, a niobium oxide
dielectrics can be formed on the surface of niobium nitride
electrode by converting a niobium nitride electrode into niobium
oxide in an electrolyte or subjecting a niobium-containing complex
on a niobium nitride electrode to hydrolysis and/or pyrolysis. The
conversion of niobium nitride into niobium oxide in an electrolyte
can be effected usually by using an aqueous protonic acid, for
example, an aqueous 0.1% phosphoric acid solution or sulfuric acid
solution. In the case where niobium nitride is formed into the
niobium dielectrics in an electrolyte, the capacitor of the
invention is an electrolytic capacitor with a positive electrode
composed of niobium nitride. In the case where a niobium-containing
complex is subjected to hydrolysis and/or pyrolysis to yield
niobium oxide, the niobium nitride has theoretically no polarity
and can be used either as a positive electrode or a negative
electrode.
[0014] The polymeric substance dielectrics can be prepared by, as
described in Japanese Unexamined Patent Publication No. H7-63045, a
process wherein a gaseous or liquid monomer is introduced in voids
or pores within metal, followed by polymerization; a process
wherein a solution of a polymeric substance in a suitable solvent
is introduced; and a process wherein a molten polymeric substance
is introduced. As specific examples of the high polymeric
substances, there can be mentioned a fluororesin, an alkyd resin,
an acrylic resin, a polyester resin such as polyethylene
terephthalate, a vinyl resin, a xylylene resin and a phenol
resin.
[0015] The dielectric substance composed of a ceramic compound can
be prepared by a process for producing a compound with perovskite
structure on a surface of metal having voids or pores, as described
in Japanese Unexamined Patent Publication No. H7-85461. As specific
examples of the compound with peroviskite structure, there can be
mentioned BaTiO.sub.3, SrTiO.sub.3, MgTiO.sub.3and BaSnO.sub.3.
[0016] The electrode other than the niobium nitride electrode of
the capacitor of the invention is not particularly limited, and can
be composed of at least one ingredient selected from electrolytes
well known in an aluminum electrolytic capacitor industry, organic
semiconductors and inorganic semiconductors. As specific examples
of the electrolytes, there can be mentioned a mixed
dimethylformamide/ethylene glycol liquid containing 5% by weight of
isobutyltripropylammonium borontetrafluoride, and a mixed propylene
carbonate/ethylene glycol liquid containing 7% by weight of
tetraethylammonium borontetrafluoride. As examples of the organic
semiconductors, there can be mentioned an organic semiconductor
composed of benzopyroline tetramer and chloranil, an organic
semiconductor predominantly comprised of tetrathiotetracene, an
organic semiconductor predominantly comprised of
tetracyano-quinodimethane, and organic semiconductors predominantly
comprised of electrically conductive polymers represented by the
following formula (1) or (2), which are doped with a dopant. 1
[0017] wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently
represents hydrogen, an alkyl group having 1 to 6 carbon atoms or
an alkoxy group having 1 to 6 carbon atoms, X represents an oxygen,
sulfur or nitrogen atom, R.sup.5 represents only when X is a
nitrogen atom, and represents hydrogen or an alkyl group having 1
to 6 carbon atoms, R.sup.1 and R.sup.2 may form together a ring,
and R.sup.3 and R.sup.4 also may form together a ring. As specific
examples of the electrically conductive polymers of formulae (1)
and (2), there can be mentioned polyaniline, polyoxyphenylene,
polyphenylene sulfide, polythiophene, polyfuran, polypyrrole and
polymethylpyrrole. As examples of the inorganic semiconductors,
there can be mentioned inorganic semiconductors predominantly
comprised of lead dioxide or manganese dioxide, and inorganic
semiconductors composed of triiron tetraoxide. These semiconductors
may be used either alone or as a mixture of at least two
thereof.
[0018] When organic semiconductors and inorganic semi-conductors
having an electrical conductivity of 10.sup.-2 S.multidot.cm.sup.-1
to 10.sup.3 S.multidot.cm.sup.-1 are used as the organic
semiconductors and inorganic conductors, capacitors having a far
reduced impedance and a more enhanced capacitance at a high
frequency are obtained.
[0019] The structure of the capacitor of the invention may be those
which have heretofore been employed, provided that the capacitor
comprises a pair of electrodes and a dielectric intervening between
the electrodes. One specific example of the capacitor of the
invention is illustrated in FIG. 1, wherein a sintered niobium
nitride 1 composed of a plurality of sintered niobium nitride
bodies is placed as an electrode and on which niobium oxide
dielectric layers have been formed by chemically converting the
surfaces of the sintered niobium nitride bodies into niobium oxide
in an electrolyte, or by subjecting a niobium-containing complex to
hydrolysis and/or pyrolysis to produce niobium oxide on the
surfaces of the sintered niobium nitride bodies. The other
electrode is formed on the dielectric layer.
[0020] Further, a carbon paste 2 and a silver paste 3 are formed in
this order on the other electrode, and then, the thus-prepared
laminated product is encapsulated with a sealing material such as
epoxy resin to form a capacitor. The capacitor is provided with a
niobium lead 4 which has been sintered in integrated with the
sintered niobium nitride bodies or which has been welded to the
niobium nitride sintered bodies. The capacitor is assembled
together with a positive electrode lead 5 and a negative electrode
lead 6 and the assembly is enclosed by an outer resin covering
7.
[0021] The capacitor provided with the niobium lead 4, illustrated
in FIG. 1, is a rectangular parallelopiped, but, its shape is not
particularly limited thereto and may be, for example,
cylindrical.
[0022] The capacitor of the invention will now be described
specifically by the following examples.
EXAMPLES 1 TO 7
[0023] Powdery niobium having an average particle diameter of 10 to
40 .mu.m was treated at 400.degree. C. in a nitrogen atmosphere to
give powdery niobium nitride. The amount of nitrogen bound to
niobium by nitrification was about 2,000 ppm by weight. The powdery
niobium nitride was sintered at 1,500.degree. C. in vacuo to give
sintered niobium nitride bodies having a diameter of 10 mm and a
thickness of about 1 mm, and containing pores having an average
diameter of 3 .mu.m with a porosity of 45%. The wintered niobium
nitride bodies were treated in an aqueous phosphoric acid solution
at a voltage of 20 V to form a niobium oxide dielectric layer on
the surface of each sintered body.
[0024] Each of the substances for forming an electrode other than
the electrode composed of the sintered niobium nitride bodies, as
shown in Table 1, was deposited on a plurality of the dielectric
layer-formed sintered niobium nitride bodies. Further, a carbon
paste and then a silver paste were laminated in this order on the
dielectric layer-formed sintered niobium nitride bodies. Then the
thus-laminated product was encapsulated with an epoxy resin to give
a capacitor.
[0025] The capacitance at 100 kHz and the LC value at 4 V were
measured. The results are shown in Table 2.
1TABLE 1 Other electrode and Electrode forming Example No.
electrical conductivity(S .multidot. cm.sup.-1) method Example 1
Chloranil complex of Repeat of immersion in tetrathiotetracene 2
.times. 10.sup.0 solution of the compound described in the left
column, and drying Example 2 Isoquinoline complex of Repeat of
immersion in tetracyanoquinodimethane solution of the compound 3
.times. 10.sup.0 described in the left column, and drying Example 3
Dope of polyaniline in Repeat of oxidation toluenesulfonic acid 3
.times. 10.sup.1 reaction in aniline solution Example 4 Dope of
polypyrrole in Repeat of oxidation toluenesulfonic acid 5 .times.
10.sup.1 reaction in pyrrole solution Example 5 Dope of
polythiophene in Repeat of oxidation toluenesulfonic acid 4 .times.
10.sup.1 reaction in thiophene solution Example 6 Mixture of lead
dioxide and Repeat of oxidation lead sulfate reaction of lead
acetate (lead dioxide 97 wt %) solution 5 .times. 10.sup.1 Example
7 Mixture of manganese Thermal decomposition dioxide and lead
dioxide of manganese nitrate (lead dioxide 95 wt %) (250.degree. C.
twice), then 5 .times. 10.sup.1 repeat of oxidation reaction of
lead acetate solution
EXAMPLES 8 AND 9
[0026] Powdery niobium nitride having an average particle diameter
of 40 to 80 .mu.m and a bound nitrogen content of about 10,000 ppm
by weight was sintered at 1,600.degree. C. in vacuo to give
sintered niobium nitride bodies having a diameter of 10 mm and a
thickness of 1 mm, and containing pores having an average diameter
of 7 .mu.m with a porosity of 55%. The sintered niobium nitride
bodies were immersed in a bath of pentaethyl niobate liquid, and
thereafter, the sintered niobium nitride bodies taken out from the
bath were maintained at 85.degree. C. in a steam and then dried at
350.degree. C. whereby a dielectric layer composed of niobium oxide
was formed on the sintered niobium nitride bodies.
[0027] Each of chloranil complex of tetrathiotetracene (Example 8)
and a mixture of lead acetate and lead sulfate (Example 9) for
forming an electrode other than the electrode composed of the
sintered niobium nitride bodies was deposited on a plurality of the
dielectric layer-formed sintered niobium nitride bodies by the same
procedures employed in Example 1 and Example 6, respectively.
Further, a carbon paste and then a silver paste were laminated in
this order on the dielectric layer-formed sintered niobium nitride
bodies. Then the laminated product was encapsulated with an epoxy
resin to give a capacitor. The properties of the capacitor were
evaluated. The results are shown in Table 2.
COMPARATIVE EXAMPLES 1 AND 2
[0028] Powdery tantalum having an average particle diameter of 10
to 40 .mu.m was sintered at 1,500.degree. C. in vacuo to give
sintered tantalum bodies having a diameter of 10 mm and a thickness
of about 1 mm, and containing pores having an average diameter of 3
.mu.m with a porosity of 45%. The sintered tantalum bodies were
treated in an aqueous phosphoric acid solution at a voltage of 20 V
to form a tantalum oxide dielectric layer on the surface of each
sintered body.
[0029] Each of chloranil complex of tetrathiotetracene (Comparative
Example 1) and a mixture of lead acetate and lead sulfate
(Comparative Example 2) for forming an electrode other than the
electrode composed of the sintered tantalum bodies was deposited on
a plurality of the dielectric layer-formed sintered tantalum bodies
by the same procedures employed in Example 1 and Example 6,
respectively. Further, a carbon paste and then a silver paste were
laminated in this order on the dielectric layer-formed sintered
tantalum bodies, and then, the thus-laminated product was
encapsulated with an epoxy resin by the same procedures as employed
in the above-mentioned Examples to give a capacitor. The properties
of the capacitor were evaluated. The results are shown in Table
2.
COMPARATIVE EXAMPLES 3 AND 4
[0030] The procedures employed in Example 1 and Example 6 were
repeated wherein the powdery niobium was not nitrified and was
sintered to give sintered niobium bodies, and capacitors were made
from the sintered niobium bodies. The properties of the capacitors
were evaluated. The results are shown in Table 2.
2 TABLE 2 Capacitance (100 kHz) LC (4V) .mu.F .mu.A Example 1 55
0.9 Example 2 50 0.8 Example 3 60 1.2 Example 4 60 1.0 Example 5 55
1.2 Example 6 62 0.8 Example 7 60 1.0 Example 8 40 0.3 Example 9 40
0.3 Comparative Example 1 24 0.02 Comparative Example 2 26 0.04
Comparative Example 3 54 14 Comparative Example 4 57 18
EXAMPLE 10
[0031] The same sintered niobium nitride bodies as prepared in
Example 1 were immersed in a bath of pentaethyl tantalat:e liquid,
and thereafter, the sintered niobium nitride bodies taken out from
the bath were maintained at 85.degree. C. in a steam and then dried
at 450.degree. C. whereby a dielectric layer composed of tantalum
oxide was formed on the sintered niobium nitride bodies.
[0032] Then an electrolyte composed of a 5% solution of
isobutyltripropylammonium borontetrafluoride electrolyte in a mixed
liquid of dimethylformamide and ethylene glycol, was applied onto
the sintered niobium nitride bodies. The electrolyte-applied
sintered niobium nitride bodies were charged in a can, and the can
was sealed to give a capacitor.
[0033] The properties of the capacitor were evaluated. The results
are shown in Table 3.
COMPARATIVE EXAMPLE 5
[0034] The procedures employed in Example 10 were repeated to make
a capacitor wherein sintered niobium bodies were used instead of
the sintered niobium nitride bodies with all other conditions
remaining the same. The properties of the capacitor were evaluated.
The results are shown in Table 3.
EXAMPLE 11
[0035] By the same procedures as employed in Example 1, sintered
niobium nitride bodies were made and then niobium oxide dielectric
layers were formed on the sintered niobium nitride bodies. An
electrolyte was applied to the dielectric layer-formed sintered
niobium nitride bodies, and the electrolyte-applied product was
charged in a can and the can was sealed to give a capacitor by the
same procedures as described in Example 10. The properties of the
capacitor were evaluated. The results are shown in Table 3.
COMPARATIVE EXAMPLE 6
[0036] The procedures as employed in Example 11 were repeated to
make a capacitor wherein sintered niobium bodies were used instead
of the sintered niobium nitride bodies with all other conditions
remaining the same. The properties of the capacitor were evaluated.
The results are shown in Table 3.
3 TABLE 3 LC (4V) .mu.A Example 10 0.3 Example 11 0.4 Comparative
Example 5 9 Comparative Example 6 10
EXAMPLE 12
[0037] By the same procedures as employed in Example 1, sintered
niobium nitride bodies were made and then niobium oxide dielectric
layers were formed on the sintered niobium nitride bodies. The
dielectric layer-formed sintered niobium nitride bodies were
immersed in an aqueous equimolar solution containing 0.01 mole/l of
iron(II) sulfate and iron(III) sulfate, and then, an excessive
amount of an aqueous sodium hydroxide solution was added whereby
triiron tetraoxide as the electrode other than the niobium nitride
electrode was formed on the dielectric layer-formed sintered
niobium nitride bodies. A carbon paste and then a silver paste were
laminated in this order on the dielectric layer-formed sintered
niobium nitride bodies, and then, the thus-laminated product was
encapsulated with an epoxy resin by the same procedures as employed
in the above-mentioned Examples to give a capacitor. The triiron
tetraoxide used had an electrical conductivity of 10.sup.-3
S.multidot.cm.sup.-1. The properties of the capacitor were
evaluated. The results are shown in Table 4.
COMPARATIVE EXAMPLE 7
[0038] The procedures as employed in Example 12 were repeated to
make a capacitor wherein sintered niobium bodies were used instead
of the sintered niobium nitride bodies with all other conditions
remaining the same. The properties of the capacitor were evaluated.
The results are shown in Table 4.
4 TABLE 4 Capacitance (100 kHz) LC (4V) .mu.F .mu.A Example 12 38
0.7 Comparative Example 7 38 16
Industrial Applicability
[0039] The capacitor of the invention with an electrode composed of
sintered niobium nitride bodies exhibits excellent environmental
stability and leak current (LC) characteristics.
[0040] Especially the capacitor having an electrode composed of
sintered niobium nitride bodies and the other electrode composed of
at least one ingredient selected from organic semiconductors and
inorganic semiconductors, and having a niobium oxide dielectric
intervening between the two electrodes has an enhanced capacitance
per unit weight at a high frequency as well as excellent leak
current (LC) characteristics. Therefore, the capacitor of the
invention is suitable for a smoothing circuit of a power
source.
* * * * *