Voltage-dependent non-linear resistance ceramic composition

Abstract

It is a voltage-dependent non-linear resistance ceramic composition comprising SrTiO.sub.3 as host material, Dy.sub.2 O.sub.3 or Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 as accelerating agent for semiconductorization, thereby changing crystal to a low resistance, and changing crystal boundary to a high resistance.In case Dy.sub.2 O.sub.3 or Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 are used as the accelerating agent for semiconductorization, one kind or more selected from the group consisting of Na, K, Ca, Cd, In, Ba, Pb, Ag, Ce, La, Sc, Y, Cs, Au, Mg, Zr, Sn, Sb, W, Bi, Ni, Fe, Ga, Pt, Tl, Al, Si, Be, Li, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru. Alternatively, in case Ta.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 are used as the accelerating agent for semiconductorization, one kind or more selected from the group consisting of Na, K, Ca, Cd, In, Ba, Pb, Mg, Zr, Sn, Sb, W, Bi, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Ga, Pt, Tl, La, Sc, Y, Cs, and Au.As a result, baristor characteristic is obtainable by means of the high resistance at crystal boundaries and capacitor between crystal granules--crystal boundary--crystal granule.From this matter, an element having both functions of the baristor characteristics and the capacitor characteristics are obtainable, and performs effect in surge absorption and noise elimination.

Description

TECHNICAL FIELD

The present invention relates to a voltage dependent non-linear resistance ceramic composition for use in surge absorbing and noise elimination in various electric apparatuses and electronic apparatuses.

BACKGROUND ART

Heretofore, in various electric apparatuses and electronic apparatuses, in order to absorb extraordinary high voltage, elimination of noise, elimination of arc, and the like, SiC baristors or varistors of ZnO system having a voltage-dependent non-linear resistance characteristics are used. Voltage-current characteristic of such baristors can be approximately represented by the following equation:

I=(V/C).sup..alpha., wherein I is current, V is voltage, C is a constant proper for the baristor, and .alpha. is a voltage non-linearity exponent.

The .alpha. of the SiC baristor is about 2-7, and for the ZnO system baristor there is ones that reaching 50. Though such baristors has superior characteristic for absorbing relatively high voltage called surge, for voltages lower than baristor voltage (for instance, absorption of noise) almost no effect is represented since its dielectric constant is low and its inherent capacitance is small, and their dielectric loss angle tan .delta. are so large as 5-10%.

On the other hand, for elimination of low voltage noise, static electricity, or the like, by appropriately selecting composition and firing condition, semiconductor ceramic capacitors having apparent dielectric constant of about 5.times.10.sup.4 -6.times.10.sup.4 and tan .delta. of about 1% are utilized.

However, these semiconductor ceramic capacitor is liable to be destroyed or become to be non-functional as capacitors when extraordinary high voltage such as surge is impressed thereon or a current above a certain limit is impressed on the element. For such reason, in the electric apparatuses or electronic apparatuses, for the purpose of both the absorbing of high voltage surge and the elimination of low voltage noise, the baristors are used being combined with capacitors and other component (for instance, coil), and for instance, a noise filter has such configuration.

FIG. 1 shows general noise filter circuit, FIG. 2 shows conventional noise filter circuit constituted by combining a baristor, capacitors and a coil, and 1 is the coil, 2 are the capacitors and 3 is the baristor.

When a noise input A shown in FIG. 5 is impressed on these circuits, output characteristic from general noise filter circuit of FIG. 1 is such as C of FIG. 5, and noise is not eliminated sufficiently. Output characteristic from the conventional noise filter circuit including a baristor shown in FIG. 2 is such as B of FIG. 5, and though noise is eliminated, such configuration has a shortcoming that it has large number of components in the inside of the apparatus and besides is contrary to tendency of miniaturization of the apparatus.

Accordingly, an electronic component, which absorbs extraordinary high voltage, can eliminate low voltage, such as noise and has small number of components, and capable of miniaturization, is demanded.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention intends to provide a voltage-dependent non-linear resistance ceramic composition comprising 80.000-99.990 mol % of SrTiO.sub.3 and as metal oxide for semiconductorization acceleration 0.005-10.000 mol % of Dy.sub.2 O.sub.3 or the above-mentioned amount of Dy.sub.2 O.sub.3 and 0.001-0.200 mol % of Nb.sub.2 O.sub.5, and is characterized by containing 0.005-10.000 mol % in the form of oxide of at least one kind of element selected from the group consisting of K, Ca, Cd, In, Ba, Cs, Zr, Sn, W, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru, which segregates at grain boundary to make the grain boundary to high resistance.

Furthermore, the present invention intends to provide a voltage-dependent non-linear resistance ceramic composition comprising 80.000-99.990 mol % of SrTiO.sub.3 and as metal oxide for semiconductorization acceleration 0.005-10.000 mol % of Ta.sub.2 O.sub.5 or the above-mentioned amount of Ta.sub.2 O.sub.5 and 0.001-0.200 mol % of Nb.sub.2 O.sub.5, and is characterized by containing 0.005-10.000 mol % in the form of oxide of at least one kind of element selected from the group consisting of Ca, Cd, In, Ba, Sn, Sb, W, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Pt, Tl, La, Y, Cs and which segregates at grain boundry to make the grain boundary to a high resistance.

The present invention can also provide a voltage-dependent non-linear resistance ceramic composition comprising 79.800-99.989 mol % of SrTiO.sub.3 and as metal oxide for semiconductorization acceleration 0.005-10.000 mol % of Dy.sub.2 O.sub.3, 0.001-0.200 mol % of Nb.sub.2 O.sub.5, and is characterized by containing 0.005-10.00 mol % in the form of oxide(s) of one or more element selected from the group consisting of Ca, Cd, In, Ba, Cs, Zr, Sn, W, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf, and Ru, which segregates at grain boundary to make the grain boundary to high resistance.

The present invention can also provide a voltage-dependent non-linear resistance ceramic composition comprising 78.000-99.989 mol % of SrTiO.sub.3 and as metal oxide for semiconductorization acceleration 0.005-10.000 mol % of Ta.sub.2 O.sub.5, 0.001-0.200 mol % of Nb.sub.2 O.sub.5, and is characterized by containing 0.005-10.000 mol % in the form of oxide(s) of one or more element selected from the group consisting of Ca, Cd, In, Ba, Sn, Sb, W, La, Y, Cs, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru, which segregates at grain boundary to make the grain boundary to high resistance.

BRIEF EXPLANATION OF THE DRAWING

FIG. 1 is a circuit diagram of a general noise filter, FIG. 2 is a circuit diagram of a noise filter using the conventional baristors and the capacitors, FIG. 3 is a sectional view of an element using voltage dependent non-linear resistance ceramic composition in accordance with the present invention, FIG. 4 is a circuit diagram of a noise filter using the voltage dependent non-linear resistance ceramic composition in accordance with the present invention, FIG. 5 is a characteristic chart showing situation of input noise and output in accordance with circuit of noise filters of the present invention and the prior art.

THE BEST MODE FOR EMBODYING THE INVENTION

As a result of accumulating various experiments the inventors propose a voltage dependent non-linear resistance ceramic composition in a different system from the conventional composition by making strontium-titanate (SrTiO.sub.3) as host material, and adding either one of Dy.sub.2 O.sub.3 or Ta.sub.2 O.sub.5 as semiconductorization accelerating agent, and by further adding depending on necessity appropriate amount of additives; hereafter the present invention is described with respect to embodiments.

EXAMPLE 1

After measuring SrTiO.sub.3 and Dy.sub.2 O.sub.3 and BaO to become composition ratio as shown in the below-mentioned Table 1, they are blended for 6 hours in wet method in a ball-mill or the like, and after drying is calcinated for 1-5 hours at 1000.degree.-1250.degree. C. in the air. Thereafter, after grinding for 4 hours in wet method in ball mill or the like and subsequently drying, and after granulating by adding 8 wt % of organic binder (for instance, polovinylalcohol), press-forming to the size of 8.0 (mm).phi..times.1.0 (mm) t with a pressing force of 1.0 t/cm.sup.2. The granulated body is fired in a reducing admosphere (for instance, N.sub.2 :H.sub.2 =10:1) at 1300.degree.-1450.degree. C. for 1-6 hours. The fired body thus obtained has a specific resistance of 0.1-0.8 .OMEGA..cm, and average granular size is 20-50.mu.m. Then, the fired body is further fired in air at 1000.degree.-1300.degree. C. for 0.5-5 hours, to obtain fired body 4 of FIG. 3. Furthermore, the both faces of the fired body 4 are ground with abrasive such as SiC. Diameter of the above-mentioned electrodes 5, 6 are selected to be 5.0 (mm) .phi..

Characteristics of the element thus obtained are shown in TABLE 1.

TABLE 1__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Dy.sub.2 O.sub.3 BaO V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 98 1.0 4.0 .times. 10.sup.3 41.62* 99.800 0 0.200 86 1.7 4.0 .times. 10.sup.3 33.73* 99.000 0 1.000 82 2.0 5.0 .times. 10.sup.3 31.94* 90.000 0 10.000 65 2.9 8.0 .times. 10.sup.3 24.75* 99.995 0.005 0 39 3.2 6.0 .times. 10.sup.3 9.66 99.990 0.005 0.005 68 6.4 1.0 .times. 10.sup.4 5.47 99.795 0.005 0.200 59 9.1 1.8 .times. 10.sup.4 3.38 98.995 0.005 1.000 43 17.7 2.0 .times. 10.sup.4 2.79 89.995 0.005 10.000 30 18.0 2.5 .times. 10.sup.4 3.510* 84.995 0.005 15.000 26 11.5 2.6 .times. 10.sup.4 8.811* 99.800 0.200 0 16 5.1 8.0 .times. 10.sup.3 6.112 99.795 0.200 0.005 53 17.7 1.7 .times. 10.sup.4 3.413 99.600 0.200 0.200 45 18.7 2.4 .times. 10.sup.4 2.314 98.800 0.200 1.000 31 21.3 2.9 .times. 10.sup.4 2.515 89.800 0.200 10.000 23 23.4 3.6 .times. 10.sup.4 3.216* 84.800 0.200 15.000 22 20.5 3.7 .times. 10.sup.4 11.117* 99.000 0.200 0 13 6.0 9.0 .times. 10.sup.3 8.018 98.995 1.000 0.005 40 13.2 1.4 .times. 10.sup.4 2.819 98.800 1.000 0.200 32 18.2 2.6 .times. 10.sup.4 2.320 98.000 1.000 1.000 19 21.8 3.1 .times. 10.sup.4 2.121 89.000 1.000 10.000 15 20.2 3.8 .times. 10.sup.4 3.122* 84.000 1.000 15.000 16 20.1 4.2 .times. 10.sup.4 9.423* 90.000 10.000 0 21 6.4 5.0 .times. 10.sup.3 9.424 89.995 10.000 0.005 34 15.4 1.8 .times. 10.sup.4 3.125 89.800 10.000 0.200 29 22.0 2.2 .times. 10.sup.4 2.226 89.000 10.000 1.000 18 23.8 2.6 .times. 10.sup.4 2.427 80.000 10.000 10.000 10 17.7 1.9 .times. 10.sup.4 3.528* 75.000 10.000 15.000 14 13.2 1.7 .times. 10.sup.4 6.929* 85.000 15.000 0 38 5.3 7.0 .times. 10.sup.3 10.730* 84.995 15.000 0.005 23 8.6 8.0 .times. 10.sup.3 8.731* 84.800 15.000 0.200 17 11.8 9.0 .times. 10.sup.3 9.732* 84.000 15.000 1.000 19 9.8 1.0 .times. 10.sup.4 9.933* 75.000 15.000 10.000 24 8.7 8.0 .times. 10.sup.3 15.834* 70.000 15.000 15.000 39 4.2 4.0 .times. 10.sup.3 18.1__________________________________________________________________________

Herein, evaluation of characteristics of the elements as baristor can be made by .alpha. and C in a voltage-current characteristic equation:

I=(V/C).sup..alpha. (wherein I is current, V is voltage, C is a constant proper to the baristor and .alpha. is a non-linearity exponent). Since accurate measurement of C is difficult, in the present invention, characteristic assesment as baristor is made by the value of baristor voltage for unit thickness when 1 mA of baristor current is flowed (hereinafter is called as V.sub.1 mA/mm.) and by a value of .alpha.=1/log (V.sub.10 mA/V.sub.1 mA) (wherein V.sub.10 mA is a baristor voltage when a baristor current of 10 mA is flowed and V.sub.1 mA is a baristor voltage when baristor current of 1 mA is flowed).

And characteristic assessment as the capacitors are made by a dielectric constant and dielectric loss tan .delta. at a measurement frequency of 1 KHz. The above-mentioned data are those for firing temperature and time in the reducing atmosphere was 1400.degree. C. and 2 hours, respectively and firing temperature and time in air was 1200.degree. C. and 3 hours, respectively.

EXAMPLE 2

SrTiO.sub.3, Dy.sub.2 O.sub.4 and ZrO.sub.2 are in a composition ratio shown in the below-mentioned TABLE 2, and mixing, forming and firings are carried in a similar operation as the above-mentioned EXAMPLE 1, and measurements are made in the similar conditions and results are shown in TABLE 2.

TABLE 2__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Dy.sub.2 O.sub.3 ZrO.sub.2 V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 101 1.0 4.0 .times. 10.sup.3 9.22* 99.800 0 0.200 127 1.9 4.0 .times. 10.sup.3 4.43* 99.000 0 1.000 171 2.3 7.0 .times. 10.sup.3 1.34* 90.000 0 10.000 196 2.8 8.0 .times. 10.sup.3 4.55* 99.995 0.005 0 39 3.2 6.0 .times. 10.sup.3 9.66 99.990 0.005 0.005 64 6.7 1.1 .times. 10.sup.4 5.47 99.795 0.005 0.200 71 10.3 1.7 .times. 10.sup.4 2.98 98.995 0.005 1.000 78 19.8 2.2 .times. 10.sup.4 2.49 89.995 0.005 10.000 86 21.0 2.7 .times. 10.sup.4 2.610* 84.995 0.005 15.000 95 17.8 2.7 .times. 10.sup.4 7.411* 99.800 0.200 0 16 5.1 8.0 .times. 10.sup.3 6.112 99.795 0.200 0.005 56 14.2 1.9 .times. 10.sup.4 3.213 99.600 0.200 0.200 51 19.9 3.1 .times. 10.sup.4 2.814 98.800 0.200 1.000 49 22.0 3.5 .times. 10.sup.4 2.315 89.800 0.200 10.000 58 20.7 3.8 .times. 10.sup.4 2.916* 84.800 0.200 15.000 81 19.7 3.2 .times. 10.sup.4 9.217* 99.000 1.000 0 13 6.0 9.0 .times. 10.sup.3 8.018 98.995 1.000 0.005 59 12.4 2.0 .times. 10.sup.4 3.719 98.800 1.000 0.200 65 19.9 3.1 .times. 10.sup.4 3.120 98.000 1.000 1.000 77 20.9 3.8 .times. 10.sup.4 3.221 89.000 1.000 10.000 83 22.0 4.4 .times. 10.sup.4 3.922* 84.000 1.000 15.000 107 14.6 4.3 .times. 10.sup.4 9.823* 90.000 10.000 0 21 6.4 5.0 .times. 10.sup.3 9.424 89.800 10.000 0.005 90 16.9 1.8 .times. 10.sup.4 4.025 89.800 10.000 0.200 95 19.4 2.6 .times. 10.sup.4 3.326 89.000 10.000 1.000 98 21.9 3.1 .times. 10.sup.4 3.027 80.000 10.000 10.000 140 23.3 2.9 .times. 10.sup.4 4.728* 75.000 10.000 15.000 171 21.0 2.7 .times. 10.sup.4 6.929* 85.000 15.000 0 38 5.3 7.0 .times. 10.sup.3 10.730* 84.995 15.000 0.005 92 9.4 8.0 .times. 10.sup.3 8.031* 84.800 15.000 0.200 96 11.2 1.0 .times. 10.sup.4 8.032* 84.000 15.000 1.000 117 10.8 1.1 .times. 10.sup.4 9.733* 75.000 15.000 10.000 169 9.5 7.0 .times. 10.sup.3 12.434* 70.000 15.000 15.000 192 9.0 4.0 .times. 10.sup.3 23.3__________________________________________________________________________ *Comparison sample

EXAMPLE 3

SrTiO.sub.3, Dy.sub.2 O.sub.3 and NiO are in a composition ratio shown in the below-mentioned TABLE 3, and mixing, forming and firings are carried in a similar operation as the above-mentioned EXAMPLE 1, and measurements are made in the similar conditions and results are shown in TABLE 3.

TABLE 3__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Dy.sub.2 O.sub.3 NiO V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 98 1.0 4.0 .times. 10.sup.3 40.42* 99.800 0 0.200 90 1.8 4.0 .times. 10.sup.3 33.93* 99.000 0 1.000 87 2.1 5.0 .times. 10.sup.3 30.04* 90.000 0 10.000 62 2.9 9.0 .times. 10.sup.3 26.05* 99.995 0.005 0 39 3.2 6.0 .times. 10.sup.3 9.66 99.990 0.005 0.005 78 6.1 1.0 .times. 10.sup.4 6.47 99.795 0.005 0.200 60 9.4 1.6 .times. 10.sup.4 3.28 98.995 0.005 1.000 44 16.8 1.9 .times. 10.sup.4 2.69 89.995 0.005 10.000 29 18.3 2.2 .times. 10.sup.4 3.910* 84.995 0.005 15.000 25 10.7 2.6 .times. 10.sup.4 8.011* 99.800 0.200 0 16 5.1 8.0 .times. 10.sup.3 6.112 99.795 0.200 0.005 63 14.7 2.1 .times. 10.sup.4 3.813 99.660 0.200 0.200 50 17.1 2.9 .times. 10.sup.4 2.814 98.880 0.200 1.000 36 20.3 3.2 .times. 10.sup.4 2.615 89.880 0.200 10.000 26 19.4 3.5 .times. 10.sup.4 3.416* 84.800 0.200 15.000 23 18.1 3.8 .times. 10.sup.4 8.817* 99.000 1.000 0 13 6.0 9.0 .times. 10.sup.3 8.018 98.995 1.000 0.005 51 14.0 2.5 .times. 10.sup.4 3.019 98.800 1.000 0.200 32 19.1 3.2 .times. 10.sup.4 2.720 98.000 1.000 1.000 21 22.7 3.7 .times. 10.sup.4 2.421 89.000 1.000 10.000 17 23.6 38 .times. 10.sup.4 2.822* 84.000 1.000 15.000 16 23.2 4.4 .times. 10.sup.4 10.123* 90.000 10.000 0 21 6.4 5.0 .times. 10.sup.3 9.424 89.995 10.000 0.005 44 15.4 1.8 .times. 10.sup.4 3.125 89.800 10.000 0.200 31 20.9 2.2 .times. 10.sup.4 2.426 89.000 10.000 1.000 19 22.0 2.4 .times. 10.sup.4 3.027 80.000 10.000 10.000 12 13.9 1.9 .times. 10.sup.4 4.628* 75.000 10.000 15.000 14 9.8 1.5 .times. 10.sup.4 6.329* 85.000 15.000 0 38 5.3 7.0 .times. 10.sup.3 10.730* 84.995 15.000 0.005 22 9.9 7.0 .times. 10.sup.3 8.131* 84.800 15.000 0.200 17 12.3 9.0 .times. 10.sup.3 7.932* 84.000 15.000 1.000 14 9.9 8.0 .times. 10.sup.3 9.233* 75.000 15.000 10.000 19 8.7 7.0 .times. 10.sup.3 9.834* 70.000 15.000 15.000 35 6.3 5.0 .times. 10.sup.3 22.1__________________________________________________________________________ *Comparison sample

EXAMPLE 4

SrTiO.sub.3, Dy.sub.2 O.sub.3 and SiO.sub.2 are in a composition ratio shown in the below-mentioned TABLE 4, and mixing, forming and firings are carried in a similar operation as the above-mentioned EXAMPLE 1, and measurements are made in the similar conditions and results are shown in TABLE 4.

TABLE 4__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Dy.sub.2 O.sub.3 SiO.sub.2 V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 90 1.0 3.0 .times. 10.sup.3 35.02* 99.800 0 0.200 106 1.5 2.0 .times. 10.sup.3 38.13* 99.000 0 1.000 114 2.6 3.0 .times. 10.sup.3 41.44* 90.000 0 10.000 198 2.7 4.0 .times. 10.sup.3 59.35* 99.995 0.005 0 39 3.2 6.0 .times. 10.sup.3 9.66 99.990 0.005 0.005 40 8.1 1.3 .times. 10.sup.4 4.27 99.795 0.005 0.200 37 10.2 1.7 .times. 10.sup.4 3.88 98.995 0.005 1.000 35 12.5 1.5 .times. 10.sup.4 2.99 89.995 0.005 10.000 43 14.9 1.4 .times. 10.sup.4 3.010* 84.995 0.005 15.000 60 15.2 9.0 .times. 10.sup.3 8.111* 99.800 0.200 0 16 5.1 8.0 .times. 10.sup.3 6.112 99.795 0.200 0.005 17 10.5 1.6 .times. 10.sup.4 3.913 99.600 0.200 0.200 15 14.2 3.0 .times. 10.sup.4 3.014 98.800 0.200 1.000 24 18.7 4.5 .times. 10.sup.4 2.915 89.800 0.200 10.000 30 19.2 4.4 .times. 10.sup.4 3.316* 84.800 0.200 15.000 58 16.2 2.5 .times. 10.sup.4 7.917* 99.000 1.000 0 13 6.0 9.0 .times. 10.sup.3 8.018 98.995 1.000 0.005 15 10.0 1.8 .times. 10.sup.4 3.119 98.800 1.000 0.200 25 12.6 3.0 .times. 10.sup.4 3.320 98.000 1.000 1.000 34 15.7 2.3 .times. 10.sup.4 3.721 89.000 1.000 10.000 55 16.4 1.9 .times. 10.sup.4 4.822* 84.000 1.000 15.000 90 14.4 1.0 .times. 10.sup.4 7.523* 90.000 10.000 0 64 6.4 5.0 .times. 10.sup.3 9.424 89.995 10.000 0.005 109 10.9 1.2 .times. 10.sup.4 2.625 89.800 10.000 0.200 156 15.6 1.9 .times. 10.sup.4 2.926 89.000 10.000 1.000 162 16.2 1.4 .times. 10.sup.4 3.127 80.000 10.000 10.000 178 17.8 1.3 .times. 10.sup.4 3.528* 75.000 10.000 15.000 190 19.0 9.0 .times. 10.sup.3 6.529* 85.000 15.000 0 53 5.3 7.0 .times. 10.sup.3 10.730* 84.995 15.000 0.005 75 7.5 1.7 .times. 10.sup.4 9.831* 84.800 15.000 0.200 76 7.6 1.5 .times. 10.sup.4 10.232* 84.000 15.000 1.000 81 8.1 1.1 .times. 10.sup.4 18.433* 75.000 15.000 10.000 93 9.3 7.0 .times. 10.sup.3 24.434* 70.000 15.000 15.000 65 6.5 4.0 .times. 10.sup.3 29.3__________________________________________________________________________ *Comparison sample

As shown by EXAMPLEs 1 through 4, Dy.sub.2 O.sub.3 with its added value in a range of 0.005-10.000 mol %, contributes to reduce specific resistance of the reduced fired body, and by re-firing in air it shows baristor characteristics.

This is because that granules and grain boundaries of fied body obtained by the reduced firing is of low resistances, and by re-firing in the air only crystal boundaries become to high resistance thereby forming electric barriers.

However, when only Dy.sub.2 O.sub.3 is added, the electric barrier formed at the grain boundaries are small, and the baristor characteristics are relatively small.

Accordingly, by adding additives such as BaO, ZrO.sub.2, NiO, SiO.sub.2, Gd.sub.2 O.sub.3, the additive is segregated at the grain boundaries during the reduced firing, and by re-firing in the air such additive forms large electric barrier at the grain boundary, thereby making the baristor characteristics large.

And, by making the crystal grain boundary only in high resistance, capacitance characteristics is presented between crystal granule--crystal grain boundaries--crystal granules.

Accordingly, by adding Dy.sub.2 O.sub.3 and additive such as BaO, CeO.sub.2, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, ZrO.sub.2, NiO, Ga.sub.2 O.sub.3, SiO.sub.2, to SrTiO.sub.3, it is possible to provide characteristics combining the baristor characteristics and the capacitance characteristics.

The case such effect is presented is within a range that Py.sub.2 O.sub.3 is 0.005-10.000 mol %, BaO, ZrO.sub.2, NiO, SiO.sub.2 or is 0.005-10.000 mol %.

Though in the above-mentioned EXAMPLEs 1-9, the elucidation was made for the cases where an additive was added in a single one, it was confirmed that when in place of the above-mentioned, an oxide of Ca, Cd, In, Cs, Sn, W, Fe, Pt, Tl, Be, Li, Lu, Th, Ir, Os, Hf, Ru as single one in a range of the above-mentioned predetermined amount was added, the similar effect was obtained.

Besides, it was confirmed that the same effect was obtained even when two kinds or more of oxides of these Ca, Cd, In, Ba, Pb, Cs, Zr, Sn, W, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru were used in a manner that total added amount is within the above-mentioned range.

EXAMPLE 5

After measuring SrTiO.sub.3, extremely small amount of Nb.sub.2 O.sub.5 which was existing from the initial stage of material (Nb.sub.2 O.sub.5 content in the material used in the present example was 0.050 mol %), Dy.sub.2 O.sub.3 as oxide of metal for acceleration of semiconductorization and CaO as element to improve non-linearity to become composition ratios shown in the below-mentioned TABLE 10, they were mixed and ground and dried, and thereafter calcinated at 1000.degree. C. for 4 hours. Thereafter, it was ground in wet method by ball mill or the like for 4 hours, and dried, and subsequently, after granulating adding 8 wt % of an organic binder (for instance, polyvinylalcohol), press-formed into a shape of disc of 8.0.phi. (mm).times.1.0 t (mm) with forming pressure of about 1.0 t/cm.sup.2. The formed body was fired for 4 hours in a reducing atmosphere (for instance, N.sub.2 :H.sub.2 =1:1, flow rate is 1.0 l/min) and at 1350.degree. C. Specific resistance of the fired body thus obtained was averagely 0.3 .OMEGA..cm, and average granule size was 30 .mu.m.

Nextly, the above-mentioned fired body was baked in the air for 2 hours at 1300.degree. C. to obtain a sintered body 4 of FIG. 3. And both faces of the above-mentioned sintered body 4 are ground by using an abrasive such as SiC or the like, and electrodes 5, 6 are formed by using conductive metal such as Ag on the ground faces. Sizes of the electrodes 5, 6 are circle of 5.0.phi. (mm).

Characteristics of the devices thus obtained are shown in TABLE 5.

TABLE 5__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Dy.sub.2 O.sub.3 Cao V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 100 1.0 4.0 .times. 10.sup.3 41.62* 99.750 0.050 0 0.200 88 1.2 4.0 .times. 10.sup.3 33.73* 98.950 0.050 0 1.000 84 1.4 5.0 .times. 10.sup.3 31.94* 89.950 0.050 0 10.000 75 1.7 9.0 .times. 10.sup.3 27.45* 99.945 0.050 0.005 0 41 3.2 6.0 .times. 10.sup.3 9.86 99.940 0.050 0.005 0.005 70 6.4 1.0 .times. 10.sup.4 5.37 99.745 0.050 0.005 0.200 61 9.0 1.8 .times. 10.sup.4 3.38 98.945 0.050 0.005 1.000 48 11.7 2.1 .times. 10.sup.4 2.79 89.945 0.050 0.005 10.000 43 12.0 2.3 .times. 10.sup.4 3.910* 84.945 0.050 0.005 15.000 40 11.5 2.5 .times. 10.sup.4 8.411* 99.750 0.050 0.200 0 36 5.1 7.0 .times. 10.sup.3 6.712 99.745 0.050 0.200 0.005 68 7.7 1.1 .times. 10.sup.4 2.413 99.550 0.050 0.200 0.200 65 10.2 1.7 .times. 10.sup.4 2.314 98.750 0.050 0.200 1.000 61 11.3 2.4 .times. 10.sup.4 2.515 89.750 0.050 0.200 10.000 61 12.4 2.9 .times. 10.sup.4 2.616* 84.750 0.050 0.200 15.000 60 11.5 2.6 .times. 10.sup.4 8.717* 98.950 0.050 1.000 0 33 6.0 8.0 .times. 10.sup.3 8.018 98.945 0.050 1.000 0.005 65 8.2 1.0 .times. 10.sup.4 2.819 98.750 0.050 1.000 0.200 57 10.8 1.6 .times. 10.sup.4 2.420 97.950 0.050 1.000 1.000 49 11.2 2.1 .times. 10.sup.4 2.621 88.950 0.050 1.000 10.000 45 12.1 2.8 .times. 10.sup.4 3.322* 83.950 0.050 1.000 15.000 54 11.6 2.4 .times. 10.sup.4 10.423* 89.950 0.050 10.000 0 42 6.4 5.0 .times. 10.sup.3 9.424 89.945 0.050 10.000 0.005 64 8.5 1.0 .times. 10.sup.4 3.025 89.750 0.050 10.000 0.200 59 9.9 1.7 .times. 10.sup.4 2.426 88.950 0.050 10.000 1.000 48 11.0 2.0 .times. 10.sup.4 2.727 79.950 0.050 10.000 10.000 60 12.4 2.9 .times. 10.sup.4 3.928* 74.950 0.050 10.000 15.000 64 10.2 2.7 .times. 10.sup.4 10.729* 84.950 0.050 15.000 0 85 5.0 7.0 .times. 10.sup.3 10.530* 84.945 0.050 15.000 0.005 83 8.6 8.0 .times. 10.sup.3 8.231* 83.750 0.050 15.000 0.200 77 10.8 9.0 .times. 10.sup.3 9.932* 83.950 0.050 15.000 1.000 79 9.8 9.0 .times. 10.sup.3 10.333* 74.950 0.050 15.000 10.000 94 8.1 8.0 .times. 10.sup.3 15.934* 69.950 0.050 15.000 15.000 128 5.4 5.0 .times. 10.sup.3 19.1__________________________________________________________________________ *Comparison sample

EXAMPLE 6

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Dy.sub.2 O.sub.3 as oxide of metal for accelerating semicondoctorization and ZrO.sub.2 as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 5. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 6.

TABLE 6__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Dy.sub.2 O.sub.3 ZrO.sub.2 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 103 1.0 4.0 .times. 10.sup.3 39.22* 99.750 0.050 0 0.200 129 1.3 4.0 .times. 10.sup.3 34.43* 98.950 0.050 0 1.000 173 1.9 7.0 .times. 10.sup.3 31.54* 89.950 0.050 0 10.000 198 2.0 8.0 .times. 10.sup.3 24.75* 99.945 0.050 0.005 0 41 3.2 6.0 .times. 10.sup.3 9.86 99.940 0.050 0.005 0.005 66 6.7 9.0 .times. 10.sup.3 5.47 99.745 0.050 0.005 0.200 73 9.3 1.1 .times. 10.sup.4 2.98 98.945 0.050 0.005 1.000 80 10.3 1.5 .times. 10.sup.4 2.79 89.945 0.050 0.005 10.000 88 11.0 1.7 .times. 10.sup.4 2.810* 84.945 0.050 0.005 15.000 97 11.4 1.8 .times. 10.sup.4 7.411* 99.750 0.050 0.200 0 36 5.1 7.0 .times. 10.sup.3 6.712 99.745 0.050 0.200 0.005 76 8.2 1.3 .times. 10.sup.4 3.213 99.550 0.050 0.200 0.200 71 9.9 1.7 .times. 10.sup.4 2.814 98.750 0.050 0.200 1.000 69 10.0 1.9 .times. 10.sup.4 2.515 89.750 0.050 0.200 10.000 78 10.7 2.5 .times. 10.sup.4 2.916* 84.750 0.050 0.200 15.000 101 11.2 2.1 .times. 10.sup.4 9.217* 98.950 0.050 1.000 0 33 6.0 8.0 .times. 10.sup.3 8.018 98.945 0.050 1.000 0.005 79 9.9 1.5 .times. 10.sup.4 2.719 98.750 0.050 1.000 0.200 85 10.4 1.9 .times. 10.sup.4 2.520 97.950 0.050 1.000 1.000 97 11.0 2.1 .times. 10.sup.4 2.421 88.950 0.050 1.000 10.000 103 12.0 2.8 .times. 10.sup.4 3.022* 83.950 0.050 1.000 15.000 127 11.6 2.3 .times. 10.sup.4 10.023* 89.950 0.050 10.000 0 42 6.4 5.0 .times. 10.sup.3 9.424 89.945 0.050 10.000 0.005 110 10.4 1.8 .times. 10.sup.4 3.225 89.750 0.050 10.000 0.200 115 10.9 2.0 .times. 10.sup.4 2.826 88.950 0.050 10.000 1.000 119 11.8 2.1 .times. 10.sup.4 3.527 79.950 0.050 10.000 10.000 160 12.3 2.6 .times. 10.sup.4 4.728* 74.950 0.050 10.000 15.000 191 11.0 2.0 .times. 10.sup.4 11.929* 84.950 0.050 15.000 0 85 5.0 7.0 .times. 10.sup.3 10.530* 84.945 0.050 15.000 0.005 112 9.4 7.0 .times. 10.sup.3 8.031* 84.750 0.050 15.000 0.200 116 10.2 8.0 .times. 10.sup.3 9.232* 83.950 0.050 15.000 1.000 137 10.3 9.0 .times. 10.sup.3 9.733* 74.950 0.050 15.000 10.000 189 9.0 7.0 .times. 10.sup.3 12.634* 69.950 0.050 15.000 15.000 212 8.7 4.0 .times. 10.sup.3 23.4__________________________________________________________________________ *Comparison sample

EXAMPLE 7

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Dy.sub.2 O.sub.3 as oxide of metal for accelerating semiconductorization and NiO as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 5. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 7.

TABLE 7__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Dy.sub.2 O.sub.3 NiO V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 100 1.0 4.0 .times. 10.sup.3 40.42* 99.750 0.050 0 0.200 92 1.2 4.0 .times. 10.sup.3 35.93* 98.950 0.050 0 1.000 89 1.3 5.0 .times. 10.sup.3 30.24* 89.950 0.050 0 10.000 64 1.7 7.0 .times. 10.sup.3 26.05* 99.945 0.050 0.005 0 41 3.2 6.0 .times. 10.sup.3 9.86 99.940 0.050 0.005 0.005 80 6.1 9.0 .times. 10.sup.3 6.47 99.745 0.050 0.005 0.200 62 9.4 1.0 .times. 10.sup.4 3.58 98.945 0.050 0.005 1.000 46 10.2 1.4 .times. 10.sup.4 2.99 89.945 0.050 0.005 10.000 31 10.3 1.6 .times. 10.sup.4 3.810* 84.945 0.050 0.005 15.000 35 10.7 1.9 .times. 10.sup.4 8.011* 99.750 0.050 0.200 0 36 5.1 7.0 .times. 10.sup.3 6.712 99.745 0.050 0.200 0.005 85 7.4 1.1 .times. 10.sup.4 5.413 99.550 0.050 0.200 0.200 70 10.1 1.7 .times. 10.sup.4 3.814 98.750 0.050 0.200 1.000 56 10.3 1.9 .times. 10.sup.4 2.615 89.750 0.050 0.200 10.000 49 11.4 2.0 .times. 10.sup.4 2.716* 84.750 0.050 0.200 15.000 43 11.1 2.5 .times. 10.sup.4 8.817* 98.950 0.050 1.000 0 33 6.0 8.0 .times. 10.sup.3 8.018 98.945 0.050 1.000 0.005 71 9.1 1.9 .times. 10.sup.4 5.119 98.750 0.050 1.000 0.200 62 10.7 2.0 .times. 10.sup.4 3.020 97.950 0.050 1.000 1.000 51 11.1 2.5 .times. 10.sup.4 2.621 88.950 0.050 1.000 10.000 47 12.2 2.7 .times. 10.sup.4 2.822* 83.950 0.050 1.000 15.000 46 12.6 2.7 .times. 10.sup.4 10.423* 89.950 0.050 10.000 0 42 6.4 5.0 .times. 10.sup.3 9.424 89.945 0.050 10.000 0.005 64 10.4 1.8 .times. 10.sup.4 4.825 89.750 0.050 10.000 0.200 61 10.9 2.0 .times. 10.sup.4 3.026 88.950 0.050 10.000 1.000 58 11.0 2.2 .times. 10.sup.4 2.927 79.950 0.050 10.000 10.000 52 10.8 1.9 .times. 10.sup.4 3.628* 74.950 0.050 10.000 15.000 60 9.2 1.5 .times. 10.sup.4 14.129* 84.950 0.050 15.000 0 85 5.0 7.0 .times. 10.sup.3 10.530* 84.945 0.050 15.000 0.005 82 9.4 7.0 .times. 10.sup.3 9.131* 84.750 0.050 15.000 0.200 67 10.3 8.0 .times. 10.sup.3 8.932* 83.950 0.050 15.000 1.000 64 9.1 9.0 .times. 10.sup.3 9.233* 74.950 0.050 15.000 10.000 79 8.6 7.0 .times. 10.sup.3 10.834* 69.950 0.050 15.000 15.000 135 6.2 7.0 .times. 10.sup.3 23.1__________________________________________________________________________ *Comparison sample

As shown by EXAMPLEs 5 through 7, in a case Dy.sub.2 O.sub.3 with its added value of 0.005-10.000 mol % and small amount of Nb.sub.2 O.sub.5 contributes to reduce specific resistance of the reduced fired body, and by re-firing in air it shows baristor characteristics.

Herein, the amount of Nb.sub.2 O.sub.5 is that of impurity naturally included in starting material TiO.sub.2, and is in a range of 0.001-0.200 mol % as a result of analysis.

Though for semiconductorization of SrTiO.sub.3, Dy.sub.2 O.sub.3 is effective, the effect of Dy.sub.2 O.sub.3 is not damaged even in the case wherein Nb.sub.2 O.sub.5 is contained at the same time. Accordingly, even when Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 are used at the same time as accelerating agent for semiconductorization, it is possible to produce the baristor characteristics.

However, in the case when Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 only are added, the electric barrier formed at the grain boundaries is low, and the baristor characteristics are relatively small.

Therefore, when such additive as CaO, ZrO.sub.2, NiO, Ga.sub.2 O.sub.3, or the like is added, the added substance is segregated at the crystal granule boundaries during the reducing firing, and by re-firing the air these additives contribute to make the crystal grain boundaries in high resistance, and the baristor characteristics become greater.

Besides, since only the crystal grain boundaries only becomes high resistance, capacitance characteristic is presented between crystal grain-crystal grain boundary-crystal grain.

Accordingly, by adding Dy.sub.2 O.sub.3, Nb.sub.2 O.sub.5 and CaO, ZrO.sub.2, NiO, to SrTiO.sub.3, it is possible to provide characteristics combining the baristor characteristics and the capacitance characteristics. The case such effect is presented is within a range that Dy.sub.2 O.sub.3 is 0.005-10.000 mol %, Nb.sub.2 O.sub.5 is 0.001-0.200 mol %, CaO, ZrO.sub.2, NiO, or Ga.sub.2 O.sub.3 or is 0.005-10.000 mol %.

Though in the above-mentioned EXAMPLEs 5-7, the cases where an additive is added in a single one, it was confirmed that even when in place of the above-mentioned, an oxide of Cd, In, Ba, Cs, Sn, W, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru as single one in a range of the above-mentioned predetermined amount was added, the similar effect was obtained.

Besides, it was confirmed that the same effect was obtained even when two kinds or more of oxides of these Ca, Cd, In, Ba, Cs, Zr, Sn, W, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru were used in a manner that total added amount is within the above-mentioned range.

By using elements 7 made by providing electrodes by conductive material such as Ag on the sintered body obtained as above and a coil 8, a noise filter shown in FIG. 4 is constituted, and by impressing noise input A shown in FIG. 5 thereon, a noise output B was obtained.

As is obvious from this, the noise is satisfactorily eliminated, and besides, number of components decreases by combination of the element unit and the coil, enabling miniaturization.

EXAMPLE 8

After measuring SrTiO.sub.3, Ta.sub.2 O.sub.5 and CdO to become composition ratios shown in the below-mentioned TABLE 8, they were mixed in wet method in a ball mill or the like for 6 hours, and dried, and thereafter calcinated at 1000.degree.-1250.degree. C. in the air for 1-5 hours. Thereafter, it was ground in wet method by ball mill or the like for 4 hours, and dried, and subsequently, after granulating adding 8 wt % of an organic binder (for instance, polyvinylalcohol), press-formed into a shape of disc of 8.0 (mm).phi..times.1.0 (mm)t with forming pressure of about 1.0 t/cm.sup.2. The formed body was fired for 1-6 hours in a reducing atmosphere (for instance, N.sub.2 :H.sub.2 =10:1) and at 1300.degree.-1450.degree. C. Specific resistance of the fired body thus obtained was averagely 0.1-0.8 .OMEGA..cm, and average granule size was 20-50 .mu.m. Nextly, the above-mentioned fired body was baked in the air for 0.5-5 hours at 1000.degree.-1300.degree. C. to obtain a sintered body 4 of FIG. 3. And both faces of the above-mentioned sintered body 4 are ground by using an abrasive such as SiC, and electrodes 5, 6 are formed by using conductive metal such as Ag thereon. Sizes of the electrodes 5, 6 are circle of 5.0 (mm).phi..

Characteristics of the devices thus obtained are shown in TABLE 8. With respect to assesment of barristor element thus obtained, they were made in the same condition as EXAMPLE 1.

TABLE 8__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Ta.sub.2 O.sub.5 CdO V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 80 1.0 4.0 .times. 10.sup.3 35.22* 99.800 0 0.200 85 1.3 4.0 .times. 10.sup.3 36.33* 99.000 0 1.000 101 1.6 5.0 .times. 10.sup.3 43.14* 90.000 0 10.000 174 2.0 7.0 .times. 10.sup.3 57.65* 99.995 0.005 0 78 3.3 5.0 .times. 10.sup.3 8.66 99.990 0.005 0.005 60 8.8 7.0 .times. 10.sup.3 6.57 99.795 0.005 0.200 51 9.9 1.4 .times. 10.sup.4 3.78 98.995 0.005 1.000 57 11.6 1.7 .times. 10.sup.4 4.29 89.995 0.005 10.000 60 13.9 1.9 .times. 10.sup.4 4.510* 84.995 0.005 15.000 73 12.5 1.4 .times. 10.sup.4 9.711* 99.800 0.200 0 72 4.3 7.0 .times. 10.sup.3 5.112 99.795 0.200 0.005 53 9.5 1.2 .times. 10.sup.4 2.213 99.600 0.200 0.200 39 11.3 1.9 .times. 10.sup.4 2.714 98.800 0.200 1.000 43 14.3 2.0 .times. 10.sup.4 3.215 89.800 0.200 10.000 54 15.1 1.8 .times. 10.sup.4 4.416* 84.800 0.200 15.000 75 15.0 1.2 .times. 10.sup.4 9.517* 99.000 1.000 0 69 5.5 9.0 .times. 10.sup.3 7.018 98.995 1.000 0.005 41 11.9 2.3 .times. 10.sup.4 2.619 98.800 1.000 0.200 32 14.2 2.8 .times. 10.sup.4 3.820 98.000 1.000 1.000 39 18.4 2.4 .times. 10.sup.4 3.721 89.000 1.000 10.000 48 19.0 1.8 .times. 10.sup.4 4.422* 84.000 1.000 15.000 77 19.5 1.7 .times. 10.sup.4 10.823* 90.000 10.000 0 61 6.3 9.0 .times. 10.sup.3 8.424 89.995 10.000 0.005 40 13.0 1.7 .times. 10.sup.4 3.425 89.800 10.000 0.200 31 14.9 2.3 .times. 10.sup.4 3.726 89.000 10.000 1.000 42 16.9 1.9 .times. 10.sup.4 4.427 80.000 10.000 10.000 56 18.1 1.8 .times. 10.sup.4 4.228* 75.000 10.000 15.000 97 17.8 1.5 .times. 10.sup.4 12.929* 85.000 15.000 0 74 6.6 7.0 .times. 10.sup.3 9.730* 84.995 15.000 0.005 62 12.0 1.2 .times. 10.sup.4 6.331* 84.800 15.000 0.200 60 13.2 1.2 .times. 10.sup.4 7.232* 84.000 15.000 1.000 69 15.8 9.0 .times. 10.sup.3 10.633* 75.000 15.000 10.000 82 13.6 6.0 .times. 10.sup.3 14.634* 70.000 15.000 15.000 124 8.8 4.0 .times. 10.sup.3 22.7__________________________________________________________________________ *Comparison sample

EXAMPLE 9

SrTiO.sub.3, Ta.sub.2 O.sub.5 and BaO are made in composition ratios shown in Table 9, and mixing, forming and firing are made in the similar operations as those of the above-mentioned EXAMPLE 8, and measured results made under the similar condition are shown in Table 9.

TABLE 9__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Ta.sub.2 O.sub.5 BaO V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 79 1.0 4.0 .times. 10.sup.3 34.42* 99.800 0 0.200 83 1.5 4.0 .times. 10.sup.3 35.43* 99.000 0 1.000 100 1.7 5.0 .times. 10.sup.3 41.54* 90.000 0 10.000 165 2.1 7.0 .times. 10.sup.3 46.35* 99.995 0.005 0 78 3.3 5.0 .times. 10.sup.3 8.66 99.990 0.005 0.005 60 8.6 7.0 .times. 10.sup.3 6.37 99.795 0.005 0.200 49 9.7 1.5 .times. 10.sup.4 3.18 98.995 0.005 1.000 55 10.6 1.7 .times. 10.sup.4 3.89 89.995 0.005 10.000 58 12.9 2.0 .times. 10.sup.4 4.910* 84.995 0.005 15.000 72 12.5 1.4 .times. 10.sup.4 9.211* 99.800 0.200 0 72 4.3 7.0 .times. 10.sup.3 5.112 99.795 0.200 0.005 53 9.3 1.6 .times. 10.sup.4 2.713 99.600 0.200 0.200 37 10.3 2.4 .times. 10.sup.4 2.514 98.800 0.200 1.000 43 13.3 2.5 .times. 10.sup.4 2.015 89.800 0.200 10.000 51 14.1 2.0 .times. 10.sup.4 3.216* 84.800 0.200 15.000 70 15.8 1.8 .times. 10.sup.4 8.717* 99.000 1.000 0 69 5.5 9.0 .times. 10.sup.3 7.018 98.995 1.000 0.005 40 11.7 2.4 .times. 10.sup.4 2.819 98.800 1.000 0.200 23 13.6 2.8 .times. 10.sup.4 2.720 98.000 1.000 1.000 36 16.2 2.5 .times. 10.sup.4 3.821 89.00 1.000 10.000 43 18.3 2.1 .times. 10.sup.4 4.122* 84.000 1.000 15.00 75 18.7 1.4 .times. 10.sup.4 10.523* 90.000 10.000 0 61 6.3 9.0 .times. 10.sup.3 8.424 89.995 10.000 0.000 39 13.5 1.8 .times. 10.sup.4 3.725 89.800 10.000 0.200 21 15.2 2.3 .times. 10.sup.4 3.626 89.000 10.000 1.000 33 17.3 2.0 .times. 10.sup.4 3.927 80.000 10.000 10.000 45 20.0 1.8 .times. 10.sup.4 7.128* 75.000 15.000 15.00 79 19.5 1.7 .times. 10.sup.4 11.329* 85.000 0 0 74 6.6 7.0 .times. 10.sup.3 9.730* 84.995 15.000 0.005 51 12.5 1.2 .times. 10.sup.4 5.131* 84.800 15.000 0.200 50 13.7 1.3 .times. 10.sup.4 5.432* 84.000 15.000 1.000 54 16.7 9.0 .times. 10.sup.3 6.433* 75.000 15.000 10.000 79 14.5 7.0 .times. 10.sup.3 8.134* 70.000 15.000 15.000 112 9.6 4.0 .times. 10.sup.3 15.2__________________________________________________________________________ *Comparison sample

EXAMPLE 10

SrTiO.sub.3, Ta.sub.2 O.sub.5 and La.sub.2 O.sub.3 are made in composition ratios shown in Table 10, and mixing, forming and firing are made in the similar operations as those of the above-mentioned EXAMPLE 8, and measured results made under the similar condition are shown in Table 10.

TABLE 10__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Ta.sub.2 O.sub.5 La.sub.2 O.sub.3 V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 90 1.0 4.0 .times. 10.sup.3 36.42* 99.800 0 0.200 96 1.3 4.0 .times. 10.sup.3 39.23* 99.000 0 1.000 112 1.4 6.0 .times. 10.sup.3 41.54* 90.000 0 10.000 184 1.9 8.0 .times. 10.sup.3 56.95* 99.995 0.005 0 78 3.3 5.0 .times. 10.sup.3 8.66 99.990 0.005 0.005 70 9.1 7.0 .times. 10.sup.3 5.07 99.795 0.005 0.200 57 9.3 1.0 .times. 10.sup.4 3.48 98.795 0.005 1.000 61 10.8 1.3 .times. 10.sup.4 3.49 89.995 0.005 10.000 75 11.4 1.7 .times. 10.sup.4 4.510* 84.995 0.005 15.000 79 11.3 2.0 .times. 10.sup.4 8.911* 99.800 0.200 0 72 4.3 7.0 .times. 10.sup.3 5.112 99.795 0.200 0.005 63 9.6 1.0 .times. 10.sup.4 2.513 99.600 0.200 0.200 49 11.5 1.8 .times. 10.sup.4 2.414 98.800 0.200 1.000 54 14.6 2.0 .times. 10.sup.4 3.215 89.800 0.200 10.000 69 15.3 2.6 .times. 10.sup.4 4.616* 84.800 0.200 15.000 85 15.1 2.7 .times. 10.sup.4 8.517* 99.000 1.000 0 69 5.5 9.0 .times. 10.sup.3 7.018 98.995 1.000 0.005 52 12.2 1.0 .times. 10.sup.4 2.519 98.800 1.000 0.200 43 14.6 1.7 .times. 10.sup.4 3.720 98.000 1.000 1.000 53 18.9 2.1 .times. 10.sup.4 3.121 89.000 1.000 10.000 60 19.0 2.3 .times. 10.sup.4 3.222* 84.000 1.000 15.000 89 19.2 1.1 .times. 10.sup.4 9.823* 90.000 10.000 0 61 6.3 9.0 .times. 10.sup.3 8.424 89.995 10.000 0.005 51 12.7 1.7 .times. 10.sup.4 3.225 89.800 10.000 0.200 42 14.3 2.2 .times. 10.sup.4 3.526 89.000 10.000 1.000 55 15.9 2.6 .times. 10.sup.4 4.827 80.000 10.000 10.000 67 17.8 2.3 .times. 10.sup.4 4.328* 75.000 10.000 15.000 110 17.5 1.9 .times. 10.sup.4 13.029* 85.000 15.000 0 74 6.6 7.0 .times. 10.sup. 3 9.730* 84.995 15.000 0.005 72 11.0 8.0 .times. 10.sup.3 7.931* 84.800 15.000 0.200 71 12.1 8.0 .times. 10.sup.3 8.832* 84.000 15.000 1.000 78 14.0 9.0 .times. 10.sup.3 10.733* 75.000 15.000 10.000 97 12.2 7.0 .times. 10.sup.3 15.234* 70.000 15.000 15.000 136 8.3 4.0 .times. 10.sup.3 24.6__________________________________________________________________________ *Comparison sample

EXAMPLE 11

SrTiO.sub.3, Ta.sub.2 O.sub.5 and Y.sub.2 O.sub.3 are made in composition ratios shown in Table 11, and mixing, forming and firing are made in the similar operations as those of the above-mentioned EXAMPLE 8, and measured results made under the similar condition are shown in Table 11.

TABLE 11__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Ta.sub.2 O.sub.5 Y.sub.2 O.sub.3 V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 81 1.0 4.0 .times. 10.sup.3 34.62* 99.800 0 0.200 106 1.3 4.0 .times. 10.sup.3 38.23* 99.000 0 1.000 160 1.4 6.0 .times. 10.sup.3 40.54* 90.000 0 10.000 172 1.7 7.0 .times. 10.sup.3 46.85* 99.995 0.005 0 78 3.3 5.0 .times. 10.sup.3 8.66 99.990 0.005 0.005 87 9.0 1.0 .times. 10.sup.4 5.37 99.795 0.005 0.200 81 9.4 1.6 .times. 10.sup.4 3.88 98.995 0.005 1.000 86 10.9 1.9 .times. 10.sup.4 2.99 89.995 0.005 10.000 95 11.3 2.6 .times. 10.sup.4 2.210* 84.995 0.005 15.000 107 11.5 2.1 .times. 10.sup.4 7.311* 99.800 0.200 0 72 4.3 7.0 .times. 10.sup.3 5.112 99.795 0.200 0.005 70 9.2 1.5 .times. 10.sup.4 3.513 99.600 0.200 0.200 59 10.7 2.6 .times. 10.sup.4 2.014 98.800 0.200 1.000 52 13.7 3.0 .times. 10.sup.4 2.715 89.800 0.200 10.000 61 15.2 3.1 .times. 10.sup.4 2.916* 84.800 0.200 15.000 70 15.0 2.7 .times. 10.sup.4 8.717* 99.000 1.000 0 69 5.5 9.0 .times. 10.sup.3 7.018 98.995 1.000 0.005 67 12.1 1.6 .times. 10.sup.4 2.819 98.800 1.000 0.200 54 13.9 2.2 .times. 10.sup.4 2.120 98.000 1.000 1.000 58 18.2 2.7 .times. 10.sup.4 2.921 89.000 1.000 10.000 65 18.9 2.3 .times. 10.sup.4 3.922* 84.000 1.000 15.000 98 19.1 1.1 .times. 10.sup.4 8.623* 90.000 10.000 0 61 6.3 9.0 .times. 10.sup.3 8.424 89.995 10.000 0.005 57 11.7 1.7 .times. 10.sup.4 3.825 89.800 10.000 0.200 48 13.4 2.0 .times. 10.sup.4 2.426 89.000 10.000 1.000 56 15.0 2.5 .times. 10.sup.4 3.827 80.000 10.000 10.000 73 17.1 2.5 .times. 10.sup.4 3.928* 75.000 10.000 15.000 109 17.0 1.9 .times. 10.sup.4 9.329* 85.000 15.000 0 74 6.6 7.0 .times. 10.sup. 3 9.730* 84.995 15.000 0.005 70 10.9 8.0 .times. 10.sup.3 7.731* 84.800 15.000 0.200 68 11.5 9.0 .times. 10.sup.3 8.432* 84.000 15.000 1.000 78 13.7 9.0 .times. 10.sup.3 10.633* 75.000 15.000 10.000 101 10.2 8.0 .times. 10.sup.3 13.634* 70.000 15.000 15.000 139 7.3 5.0 .times. 10.sup.3 23.9__________________________________________________________________________ *Comparison sample

EXAMPLE 12

SrTiO.sub.3, Ta.sub.2 O.sub.5 and Gd.sub.2 O.sub.3 are made in composition ratios shown in Table 12, and mixing, forming and firing are made in the similar operations as those of the above-mentioned EXAMPLE 8, and measured results made under the similar condition are shown in Table 12.

TABLE 12__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Ta.sub.2 O.sub.5 Gd.sub.2 O.sub.3 V.sub.1 mA (V/mm) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.995 0 0.005 101 1.0 4.0 .times. 10.sup.3 44.62* 99.800 0 0.200 105 1.6 4.0 .times. 10.sup.3 39.13* 99.000 0 1.000 173 2.0 7.0 .times. 10.sup.3 31.34* 90.000 0 10.000 213 2.4 7.0 .times. 10.sup.3 26.05* 99.995 0.005 0 78 3.3 5.0 .times. 10.sup.3 8.66 99.990 0.005 0.005 82 6.7 7.0 .times. 10.sup.3 4.57 99.795 0.005 0.200 80 9.0 1.1 .times. 10.sup.4 3.68 98.995 0.005 1.000 87 13.7 1.5 .times. 10.sup.4 2.79 89.995 0.005 10.000 98 15.0 1.9 .times. 10.sup.4 3.210* 84.995 0.005 15.000 112 15.5 2.2 .times. 10.sup.4 6.811* 99.800 0.200 0 72 4.3 7.0 .times. 10.sup.3 5.112 99.795 0.200 0.005 80 7.1 1.1 .times. 10.sup.4 3.013 99.600 0.200 0.200 72 11.0 1.6 .times. 10.sup.4 2.514 98.800 0.200 1.000 81 14.5 2.0 .times. 10.sup.4 2.015 89.800 0.200 10.000 89 15.2 2.8 .times. 10.sup.4 2.716* 84.800 0.200 15.000 98 15.9 2.9 .times. 10.sup.4 7.417* 99.000 1.000 0 69 5.5 9.0 .times. 10.sup.3 7.018 98.995 1.000 0.005 87 10.1 1.6 .times. 10.sup.4 2.519 98.800 1.000 0.200 63 12.3 1.7 .times. 10.sup.4 2.320 98.000 1.000 1.000 68 13.2 2.3 .times. 10.sup.4 2.921 89.000 1.000 10.000 74 14.9 1.9 .times. 10.sup.4 3.122* 84.000 1.000 15.000 103 12.3 1.4 .times. 10.sup.4 8.623* 90.000 10.000 0 61 6.3 9.0 .times. 10.sup.3 8.424 89.995 10.000 0.005 65 12.5 1.8 .times. 10.sup.4 3.625 89.800 10.000 0.200 57 13.1 2.3 .times. 10.sup.4 2.026 89.000 10.000 1.000 68 13.9 2.6 .times. 10.sup.4 3.527 80.000 10.000 10.000 83 12.8 2.5 .times. 10.sup.4 3.728* 75.000 10.000 15.000 114 10.8 2.0 .times. 10.sup.4 9.129* 85.000 15.000 0 74 6.6 7.0 .times. 10.sup. 3 9.730* 84.995 15.000 0.005 84 8.4 8.0 .times. 10.sup.3 6.631* 84.800 15.000 0.200 79 8.0 9.0 .times. 10.sup.3 8.332* 84.000 15.000 1.000 85 7.6 9.0 .times. 10.sup.3 10.233* 75.000 15.000 10.000 114 7.5 8.0 .times. 10.sup.3 14.634* 70.000 15.000 15.000 148 4.6 5.0 .times. 10.sup.3 25.7__________________________________________________________________________ *Comparison sample

As shown by EXAMPLEs 8 through 12, Ta.sub.2 O.sub.5 with its added value in a range of 0.005-10.000 mol %, contributes to reduce specific resistance of the reduced fired body, and by re-firing in air it shows baristor characteristics.

This is because that granules and grain boundaries of fired body obtained by the reduced firing is of low resistances, and by re-firing in the air only crystal boundaries become to high resistance thereby forming electric barriers.

However, when only Ta.sub.2 O.sub.5 is added, the electric barrier formed at the grain boundaries are small, and the baristor characteristics are relatively small.

Accordingly, by adding additives such as CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, the additive is segregated at the grain boundaries during the reduced firing, and by re-firing in the air such additive forms large electric barrier at the grain boundary, thereby making the baristor characteristics large.

And, by making the crystal grain boundary only in high resistance, capacitance characteristics is presented between crystal granule--crystal grain boundaries--crystal granules.

Accordingly, by adding Ta.sub.2 O.sub.5 and additive S such as CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, to SrTiO.sub.3, it is possible to provide a characteristic combining the aristor characteristics and the capacitance characteristics.

The case such effect is presented is within a range that Ta.sub.2 O.sub.5 is 0.005-10.000 mol %, CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, are 0.005-10.000 mol %.

Though in the above-mentioned EXAMPLES 18-24, the elucidation was made for the cases where an additive was added in a single one, it was confirmed that when in place of the above-mentioned, an oxide of Ca, In, Cs, Sn, Sb, W, Pt, Tl, Eu, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru as single one in a range of the above-mentioned predetermined amount was added, the similar effect was obtained.

Besides, it was confirmed that the same effect was obtained even when two kinds or more of oxides of these Ca, Cd, In, Ba, La, Y, Cs, Sn, Sb, W, Pt, Tl, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru were used so that total added amount is within the above-mentioned range.

EXAMPLE 13

After measuring SrTiO.sub.3, extremely small amount of Nb.sub.2 O.sub.5 which was existing from the initial stage of material (Nb.sub.2 O.sub.5 content in the material used in the present example was 0.050 mol %), Ta.sub.2 O.sub.5 as oxide of metal for acceleration of semiconductorization and CdO as element to improve non-linearity to become composition ratios shown in the below-mentioned TABLE 13, they were mixed and ground and dried, and thereafter calcinated at 1000.degree. C. for 4 hours. Thereafter, it was ground in wet method by ball mill or the like for 4 hours, and dried, and subsequently, after granulating adding 8 wt % of an organic binder (for instance, polyvinylalcohol), press-formed into a shape of disc of 8.0 .phi. (mm).times.1.0 t (mm) with forming pressure of about 1.0 t/cm.sup.2. The formed body was fired for 4 hours in a reducing atmosphere (for instance, N.sub.2 :H.sub.2 =1:1, flow rate is 1.0 l/min) and at 1350.degree. C. Specific resistance of the fired body thus obtained was averagely 0.3 .OMEGA..cm, and average granule size was 30 .mu.m.

Nextly, the above-mentioned fired body was baked in the air for 2 hours at 1300.degree. C. to obtain a sintered body 4 of FIG. 3. And both faces of the above-mentioned sintered body 4 are ground by using an abrasive such as SiC or the like, as Ag on the ground faces. Sizes of the electrodes 5, 6 are circle of 5.0 .phi. (mm).

Characteristic of the devices thus obtained are shown in TABLE 13.

TABLE 25__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 CdO V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 75 1.0 4.0 .times. 10.sup.3 35.22* 99.750 0.050 0 0.200 80 1.3 4.0 .times. 10.sup.3 36.03* 98.950 0.050 0 1.000 96 1.6 4.0 .times. 10.sup.3 44.34* 89.950 0.050 0 10.000 164 2.1 5.0 .times. 10.sup.3 56.75* 99.945 0.050 0.005 0 80 3.0 5.0 .times. 10.sup.3 8.66 99.940 0.050 0.005 0.005 65 8.5 6.0 .times. 10.sup.3 6.47 99.745 0.050 0.005 0.200 56 9.8 1.3 .times. 10.sup.4 3.68 98.945 0.050 0.005 1.000 62 10.6 1.3 .times. 10.sup.4 4.19 89.945 0.050 0.005 10.000 65 13.5 1.7 .times. 10.sup.4 4.410* 84.945 0.050 0.005 15.000 78 11.5 1.0 .times. 10.sup.4 9.811* 99.750 0.050 0.200 0 75 3.4 5.0 .times. 10.sup.3 5.212 99.745 0.050 0.200 0.005 56 8.9 1.0 .times. 10.sup.4 2.313 99.550 0.050 0.200 0.200 42 11.0 1.2 .times. 10.sup.4 2.814 98.750 0.050 0.200 1.000 46 13.1 1.5 .times. 10.sup.4 3.015 89.750 0.050 0.200 10.000 57 14.1 1.9 .times. 10.sup.4 4.516* 84.750 0.050 0.200 15.000 78 12.5 1.1 .times. 10.sup.4 9.717* 98.950 0.050 1.000 0 71 4.5 6.0 .times. 10.sup.4 6.018 98.945 0.050 1.000 0.005 43 10.9 2.0 .times. 10.sup.4 2.519 98.750 0.050 1.000 0.200 34 13.0 2.2 .times. 10.sup.4 3.620 97.950 0.050 1.000 1.000 41 16.4 2.3 .times. 10.sup.4 3.321 88.950 0.050 1.000 10.000 51 18.0 1.5 .times. 10.sup.4 4.522* 83.950 0.050 1.000 15.000 80 15.9 1.0 .times. 10.sup.4 11.023* 89.950 0.050 10.000 0 61 4.8 6.0 .times. 10.sup.3 7.024 89.945 0.050 10.000 0.005 41 11.3 1.2 .times. 10.sup.4 3.325 89.750 0.050 10.000 0.200 32 13.1 1.7 .times. 10.sup.4 3.626 88.950 0.050 10.000 1.000 43 14.9 1.9 .times. 10.sup.4 4.327 79.950 0.050 10.000 10.000 57 15.1 1.7 .times. 10.sup.4 4.128* 74.950 0.050 10.000 15.000 98 12.0 1.4 .times. 10.sup.4 13.029* 84.950 0.050 15.000 0 79 5.1 5.0 .times. 10.sup.3 7.930* 84.945 0.050 15.000 0.005 67 10.0 1.1 .times. 10.sup.4 6.531* 84.750 0.050 15.000 0.200 65 10.3 1.1 .times. 10.sup.4 7.432* 83.950 0.050 15.000 1.000 74 11.8 1.0 .times. 10.sup.4 10.933* 74.950 0.050 15.000 10.000 90 8.9 4.0 .times. 10.sup.3 16.434* 69.950 0.050 15.000 15.000 174 6.1 4.0 .times. 10.sup.3 27.2__________________________________________________________________________ *Comparative sample

EXAMPLE 14

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Ta.sub.2 O.sub.5 as oxide of metal for accelerating semicondoctorization and BaO as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 13. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 14.

TABLE 14__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 BaO V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 84 1.0 4.0 .times. 10.sup.3 35.42* 99.750 0.050 0 0.200 88 1.4 4.0 .times. 10.sup.3 36.43* 98.950 0.050 0 1.000 105 1.5 4.0 .times. 10.sup.3 42.54* 89.950 0.050 0 10.000 170 1.7 5.0 .times. 10.sup.3 47.05* 99.945 0.050 0.005 0 80 3.0 5.0 .times. 10.sup.3 8.66 99.940 0.050 0.005 0.005 62 8.6 7.0 .times. 10.sup.3 6.37 99.745 0.050 0.005 0.200 51 9.8 9.0 .times. 10.sup.3 3.48 98.945 0.050 0.005 1.000 57 10.6 1.7 .times. 10.sup.4 3.99 89.945 0.050 0.005 10.000 60 11.9 1.9 .times. 10.sup.4 4.810* 84.945 0.050 0.005 15.000 72 11.5 1.4 .times. 10.sup.4 9.511* 99.750 0.050 0.200 0 75 3.4 5 .times. 10.sup.3 5.212 99.745 0.050 0.200 0.005 56 9.0 1.4 .times. 10.sup.4 2.713 99.550 0.050 0.200 0.200 39 10.1 1.6 .times. 10.sup.4 2.514 98.750 0.050 0.200 1.000 45 11.1 2.0 .times. 10.sup.4 2.115 89.750 0.050 0.200 10.000 54 12.3 1.8 .times. 10.sup.4 3.216* 84.750 0.050 0.200 15.000 73 13.8 1.5 .times. 10.sup.4 8.917* 98.950 0.050 1.000 0 71 4.5 6.0 .times. 10.sup.3 6.018 98.945 0.050 1.000 0.005 42 10.7 1.8 .times. 10.sup.4 2.819 98.750 0.050 1.000 0.200 25 11.7 2.0 .times. 10.sup.4 2.720 97.950 0.050 1.000 1.000 38 12.6 2.1 .times. 10.sup.4 3.821 88.950 0.050 1.000 10.000 45 13.3 1.8 .times. 10.sup.4 4.122* 83.950 0.050 1.000 15.000 80 13.0 1.5 .times. 10.sup.4 11.523* 89.950 0.050 10.000 0 61 4.8 6.0 .times. 10.sup.3 7.024 89.945 0.050 10.000 0.005 39 10.5 1.5 .times. 10.sup.4 3.525 89.750 0.050 10.000 0.200 25 11.2 1.8 .times. 10.sup.4 3.626 88.950 0.050 10.000 1.000 38 12.2 1.7 .times. 10.sup.4 3.927 79.950 0.050 10.000 10.000 50 13.0 1.6 .times. 10.sup.4 7.028* 74.950 0.050 10.000 15.000 89 14.1 1.2 .times. 10.sup.4 11.729* 84.950 0.050 15.000 0 79 5.1 5.0 .times. 10.sup.3 7.930* 84.945 0.050 15.000 0.005 56 10.5 1.1 .times. 10.sup.4 5.031* 84.750 0.050 15.000 0.200 55 11.7 1.0 .times. 10.sup.4 5.232* 83.950 0.050 15.000 1.000 59 11.9 8.0 .times. 10.sup.3 6.133* 74.950 0.050 15.000 10.000 89 11.8 5.0 .times. 10.sup.3 7.834* 69.950 0.050 15.000 15.000 121 6.1 4.0 .times. 10.sup.3 15.0__________________________________________________________________________ *Comparison sample

EXAMPLE 15

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Ta.sub.2 O.sub.5 as oxide of metal for accelerating semicondoctorization and La.sub.2 O.sub.3 as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 13. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 15.

TABLE 15__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 La.sub.2 O.sub.3 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 90 1.0 4.0 .times. 10.sup.3 35.42* 99.750 0.050 0 0.200 96 1.2 4.0 .times. 10.sup.3 39.03* 98.950 0.050 0 1.000 113 1.3 5.0 .times. 10.sup.3 40.54* 89.950 0.050 0 10.000 186 1.7 7.0 .times. 10.sup.3 56.85* 99.945 0.050 0.005 0 80 3.0 5.0 .times. 10.sup.3 8.66 99.940 0.050 0.005 0.005 72 8.2 7.0 .times. 10.sup.3 5.17 99.745 0.050 0.005 0.200 59 8.5 1.0 .times. 10.sup.4 3.08 98.945 0.050 0.005 1.000 63 9.8 1.4 .times. 10.sup.4 3.19 89.945 0.050 0.005 10.000 77 10.4 1.8 .times. 10.sup.4 4.210* 84.945 0.050 0.005 15.000 81 10.3 1.5 .times. 10.sup.4 9.811* 99.750 0.050 0.200 0 75 3.4 5.0 .times. 10.sup.3 5.212 99.745 0.050 0.200 0.005 65 8.6 1.0 .times. 10.sup.4 3.113 99.550 0.050 0.200 0.200 51 10.9 1.8 .times. 10.sup.4 2.714 98.750 0.050 0.200 1.000 54 13.2 2.0 .times. 10.sup.4 3.015 89.750 0.050 0.200 10.000 69 14.3 2.2 .times. 10.sup.4 3.216* 84.750 0.050 0.200 15.000 87 14.0 2.3 .times. 10.sup.4 8.417* 98.950 0.050 1.000 0 71 4.5 6.0 .times. 10.sup.3 6.018 98.945 0.050 1.000 0.005 53 11.2 1.0 .times. 10.sup.4 2.919 98.750 0.050 1.000 0.200 45 13.6 1.6 .times. 10.sup.4 3.520 97.950 0.050 1.000 1.000 55 16.4 2.0 .times. 10.sup.4 3.021 88.950 0.050 1.000 10.000 62 16.5 2.1 .times. 10.sup.4 3.222* 83.950 0.050 1.000 15.000 91 17.0 1.5 .times. 10.sup.4 9.923* 89.950 0.050 10.000 0 61 4.8 6.0 .times. 10.sup.3 7.024 89.945 0.050 10.000 0.005 51 10.7 1.2 .times. 10.sup.4 3.225 89.750 0.050 10.000 0.200 43 12.3 1.7 .times. 10.sup.4 3.526 88.950 0.050 10.000 1.000 57 13.9 2.1 .times. 10.sup.4 4.827 79.950 0.050 10.000 10.000 69 13.8 2.0 .times. 10.sup.4 6.128* 74.950 0.050 10.000 15.000 120 13.5 1.8 .times. 10.sup.4 11.029* 84.950 0.050 15.000 0 79 5.1 5.0 .times. 10.sup.3 7.930* 84.945 0.050 15.000 0.005 75 10.0 8.0 .times. 10.sup.3 7.531* 84.750 0.050 15.000 0.200 74 11.1 8.0 .times. 10.sup.3 7.632* 83.950 0.050 15.000 1.000 79 12.0 7.0 .times. 10.sup.3 8.133* 74.950 0.050 15.000 10.000 102 11.2 7.0 .times. 10.sup.3 10.234* 69.950 0.050 15.000 15.000 143 7.9 5.0 .times. 10.sup.3 14.6__________________________________________________________________________ *Comparison sample

EXAMPLE 16

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Ta.sub.2 O.sub.5 as oxide of metal for accelerating semicondoctorization and Y.sub.2 O.sub.3 as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 13. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 16.

TABLE 16__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 Y.sub.2 O.sub.3 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 82 1.0 4.0 .times. 10.sup.3 35.62* 99.750 0.050 0 0.200 107 1.3 4.0 .times. 10.sup.3 39.23* 98.950 0.050 0 1.000 161 1.4 4.0 .times. 10.sup.3 41.54* 89.950 0.050 0 10.000 175 1.5 7.0 .times. 10.sup.3 47.85* 99.945 0.050 0.005 0 80 3.0 5.0 .times. 10.sup.3 8.66 99.940 0.050 0.005 0.005 89 8.0 1.0 .times. 10.sup.4 5.37 99.745 0.050 0.005 0.200 83 9.0 1.5 .times. 10.sup.4 3.88 98.945 0.050 0.005 1.000 88 9.4 1.9 .times. 10.sup.4 3.49 89.945 0.050 0.005 10.000 97 10.9 2.1 .times. 10.sup.4 3.010* 84.945 0.050 0.005 15.000 111 11.3 2.0 .times. 10.sup.4 7.411* 99.750 0.050 0.200 0 75 3.4 5.0 .times. 10.sup.3 5.212 99.745 0.050 0.200 0.005 73 8.2 1.4 .times. 10.sup.4 3.613 99.550 0.050 0.200 0.200 62 9.9 1.7 .times. 10.sup.4 2.814 98.750 0.050 0.200 1.000 55 11.7 2.0 .times. 10.sup.4 2.515 89.750 0.050 0.200 10.000 64 13.2 2.1 .times. 10.sup.4 2.916* 84.750 0.050 0.200 15.000 75 13.0 2.2 .times. 10.sup.4 8.917* 98.950 0.050 1.000 0 71 4.5 6.0 .times. 10.sup.3 6.018 98.945 0.050 1.000 0.005 69 11.0 1.5 .times. 10.sup.4 2.919 98.750 0.050 1.000 0.200 58 12.5 2.0 .times. 10.sup.4 2.420 97.950 0.050 1.000 1.000 60 13.2 2.2 .times. 10.sup.4 2.821 88.950 0.050 1.000 10.000 67 13.7 2.3 .times. 10.sup.4 3.722* 83.950 0.050 1.000 15.000 101 13.1 1.7 .times. 10.sup.4 8.723* 89.950 0.050 10.000 0 61 4.8 6.0 .times. 10.sup.3 7.024 89.945 0.050 10.000 0.005 57 10.7 1.5 .times. 10.sup.4 3.725 89.750 0.050 10.000 0.200 49 11.4 1.7 .times. 10.sup.4 2.526 88.950 0.050 10.000 1.000 56 11.7 1.9 .times. 10.sup.4 3.927 79.950 0.050 10.000 10.000 73 10.7 1.9 .times. 10.sup.4 4.128* 74.950 0.050 10.000 15.000 110 10.5 2.1 .times. 10.sup.4 9.529* 84.950 0.050 15.000 0 79 5.1 5.0 .times. 10.sup.3 7.930* 84.945 0.050 15.000 0.005 75 9.9 8.0 .times. 10.sup.3 7.531* 84.750 0.050 15.000 0.200 74 10.4 8.0 .times. 10.sup.3 8.332* 83.950 0.050 15.000 1.000 80 11.3 9.0 .times. 10.sup.3 10.233* 74.950 0.050 15.000 10.000 110 10.0 9.0 .times. 10.sup.3 11.434* 69.950 0.050 15.000 15.000 149 7.2 7.0 .times. 10.sup.3 25.8__________________________________________________________________________ *Conparison sample

EXAMPLE 17

SrTiO.sub.3, very small amount of Nb.sub.2 O.sub.5 which was existing from initial stage of material (contents of Nb.sub.2 O.sub.5 of the material used in the present example was 0.050 mol %), Ta.sub.2 O.sub.5 as oxide of metal for accelerating semicondoctorization and Gd.sub.2 O.sub.3 as an element to improve non-linearity are formed, reduced and fired, and oxidated in the similar operation as that of the above-mentioned EXAMPLE 13. Results obtained by measuring in the similar condition as that of the above-mentioned of the characteristics of devices thus obtained were shown in TABLE 17.

TABLE 17__________________________________________________________________________Sample Composition ratio (mol %) CharacteristicsNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 Gd.sub. 2 O.sub.3 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________1* 99.945 0.050 0 0.005 105 1.0 4.0 .times. 10.sup.3 45.62* 99.750 0.050 0 0.200 110 1.1 4.0 .times. 10.sup.3 40.13* 98.950 0.050 0 1.000 178 1.2 5.0 .times. 10.sup.3 32.34* 89.950 0.050 0 10.000 218 1.6 8.0 .times. 10.sup.3 29.65* 99.945 0.050 0.005 0 80 3.0 5.0 .times. 10.sup.3 8.66 99.940 0.050 0.005 0.005 84 6.6 7.0 .times. 10.sup.3 4.57 99.745 0.050 0.005 0.200 82 9.7 9.0 .times. 10.sup.3 3.68 98.945 0.050 0.005 1.000 89 10.0 1.5 .times. 10.sup.4 2.69 89.945 0.050 0.205 10.000 100 12.7 1.7 .times. 10.sup.4 3.210* 84.945 0.050 0.205 15.000 121 12.9 1.9 .times. 10.sup.4 6.911* 99.750 0.050 0.200 0 75 3.4 5.0 .times. 10.sup.3 5.212 99.745 0.050 0.200 0.005 83 7.0 1.1 .times. 10.sup.4 3.013 99.550 0.050 0.200 0.200 75 9.0 1.6 .times. 10.sup.4 2.514 98.750 0.050 0.200 1.000 83 10.6 2.0 .times. 10.sup.4 2.315 89.750 0.050 1.000 10.000 92 11.2 2.4 .times. 10.sup.4 2.716* 84.750 0.050 1.000 15.000 101 11.9 2.6 .times. 10.sup.4 8.417* 98.950 0.050 1.000 0 71 4.5 6.0 .times. 10.sup.3 6.018 98.945 0.050 1.000 0.005 89 9.1 1.3 .times. 10.sup.4 2.719 98.750 0.050 1.000 0.200 65 0.3 1.4 .times. 10.sup.4 2.420 97.950 0.050 1.000 1.000 70 11.2 1.8 .times. 10.sup.4 2.921 88.950 0.050 1.000 10.000 76 12.9 1.9 .times. 10.sup.4 3.222* 83.950 0.050 1.000 15.000 106 12.3 1.7 .times. 10.sup.4 9.623* 89.950 0.050 10.000 0 61 4.8 6.0 .times. 10.sup.3 7.024 89.945 0.050 10.000 0.005 65 9.5 1.5 .times. 10.sup.4 3.525 89.750 0.050 10.000 0.200 57 10.1 1.8 .times. 10.sup.4 2.326 88.950 0.050 10.000 1.000 68 10.9 2.3 .times. 10.sup.4 3.427 79.950 0.050 10.000 10.000 84 11.8 2.5 .times. 10.sup.4 3.728* 74.950 0.050 10.000 15.000 121 10.2 2.0 .times. 10.sup.4 10.129* 84.950 0.050 15.000 0 79 5.1 5 .times. 10.sup.3 7.930* 84.945 0.050 15.000 0.005 89 8.5 8.0 .times. 10.sup.3 6.931* 84.750 0.050 15.000 0.200 84 8.1 9.0 .times. 10.sup.3 8.332* 83.950 0.050 15.000 1.000 90 7.7 9.0 .times. 10.sup.3 10.433* 74.950 0.050 15.000 10.000 119 7.5 8.0 .times. 10.sup.3 16.434* 69.950 0.050 15.000 15.000 153 5.6 6.0 .times. 10.sup.3 24.9__________________________________________________________________________ *Comparison sample

As shown by EXAMPLES 13 through 17, in a case Ta.sub.2 O.sub.5 with its added value of 0.005-10.000 mol % and small amount of Nb.sub.2 O.sub.5 contributes to reduce specific resistance of the reduced fired body, and by re-firing in air it shows baristor characteristics.

Herein, the amount of Nb.sub.2 O.sub.5 was that of impurity naturally included in starting material TiO.sub.2, and was in a range of 0.001-0.200 mol % as a result of analysis.

Though for semiconductorization of SrTiO.sub.3, Ta.sub.2 O.sub.5 is more effective than Nb.sub.2 O.sub.5, the effect of Ta.sub.2 O.sub.5 is not damaged even in the case wherein Nb.sub.2 O.sub.5 is contained at the same time. Accordingly, even when Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 are used at the same time as accelerating agent for semicondoctorization, it is possible to produce the baristor characteristics.

However, in the case when Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 only are added, the electric barrier formed at the grain boundaries is low, and the baristor characteristics are relatively small.

Therefore, when such additive as CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or the like is added, the added substance is segregated at the crystal granule boundaries during the reducing firing, and by re-firing in the air these additives contribute to make the crystal grain boundaries in high resistance, and the baristor characteristics become greater.

Besides, since only the crystal grain boundaries only becomes high resistance, capacitance characteristic is presented between crystal grain-crystal grain boundary-crystal grain.

Accordingly, by adding Ta.sub.2 O.sub.5, Nb.sub.2 O.sub.5 and such additive as CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, or Gd.sub.2 O.sub.3 to SrTiO.sub.3, it is possible to provide characteristics combining the baristor characteristics and the capacitance characteristics. The case such effect is presented is within a range that Ta.sub.2 O.sub.5 is 0.005-10.000 mol %, Nb.sub.2 O.sub.5 is 0.001-0.200 mol %, CdO, BaO, La.sub.2 O.sub.3, Y.sub.2 O.sub.3, or Gd.sub.2 O.sub.3 is 0.005-10.000 mol %.

Though in the above-mentioned EXAMPLES 25-31, the cases where an additive is added in a single one, it was confirmed that even when in place of the above-mentioned, an oxide of Ca, In, Cs, Sn, Sb, W, Pt, Tl, Eu, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru as single one in a range of the above-mentioned predetermined amount was added, the similar effect was obtained.

Besides, it was confirmed that the same effect was obtained even when two kinds or more of oxides of these Ca, Cd, In, Ba, La, Y, Cs, Sn, Sb, W, Pt, Tl, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru were used in a manner that total added amount is within the above-mentioned range.

When electrodes were provided by conductive material such as Ag or thus obtained element, and a noise filter shown in FIG. 4 was constituted therewith, and noise input A shown in FIG. 5 was impressed thereon, an output of the same characteristics as that of the noise output B was obtained.

As is apparent from this, the noise is sufficiently eliminated, and also by combining the element unit and the coil the number of component is reduced, and miniaturization becomes possible.

POSSIBLE UTILIZATION IN INDUSTRY

As has been elucidated, according to the voltage-dependent non-linear resistance ceramic composition, absorption of surge impressed on the electric and electronic apparatuses and elimination of noise can be done by a single element, and it has many functions and can be miniaturized and is indispensable for protection of semiconductor product of the electric and electronic apparatuses, and practical utility thereof is extremely great.

Claims

1. A voltage-dependent non-linear resistance ceramic composition comprising 80.000-99.990 mol % of SrTiO.sub.3 and 0.005-10.000 mol % of Dy.sub.2 O.sub.3 and 0.005-10.000 mol % in the form of oxides of at least one element selected from the group consisting of Ca, Cd, In, Ba, Cs, Zr, Sn, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru.

2. A voltage-dependent non-linear resistance ceramic composition,

which comprises

79.800-99.989 mol % of SrTiO.sub.3, 0.005-10.000 mol % of Dy.sub.2 O.sub.3, 0.001-0.200 mol % of Nb.sub.2 O.sub.5 and 0.005-10.000 mol % in the form of oxide(s) of one or more element selected from the group consisting of Ca, Cd, In, Ba, Cs, Zr, Sn, W, Ni, Fe, Pt, Tl, Si, Be, Li, Ir, Os, Hf and Ru.