Voltage-dependent non-linear resistance ceramic composition

Abstract

This is a voltage-dependent non-linear resistance ceramic composition wherein resistance of crystal is decreased by containing SrTiO.sub.3 as host material, and Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 as semiconductorization accelerating agent, and further by adding as additive one kind or more oxide of element selected from the group consisting of MnO.sub.2, Ga, Pt, Tl, Si, Ti, Li, La, Cu, Y, Cs, Au, Mo, S, Be, Al, Na, K, Ca, Cd, In, Ba, Pb, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn, Sb and W, these additive is segregated at crystal granule boundaries, thereby making the crystal granule boundaries to high resistance.Accordingly, by the high resistance layer at the crystal boundaries the varistor characteristic is obtainable, and a capacitance characteristic is obtainable between the crystal granule-crystal granule boundary-crystal granule.From this, an element having both functions of the varistor characteristics and the capacitor characteristics are obtainable, and performs effect in surge absorption and noise elemination.

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 varistors or varistors of ZnO system having a voltage-dependent non-linear resistance characteristics are used. Voltage-current characteristic of such varistors 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 varistor, and .alpha. is a voltage non-linearity exponent.

The .alpha. of the SiC varistor is about 2-7, and for the ZnO system varistor there is ones that reaching 50. Though such varistors has superior characteristic for absorbing relatively high voltage called surge, for voltages lower than varistor 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 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 volage noise, the varistors 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 a conventional noise filter circuit constituted by combining a varistor, capacitors and a coil, and 1 is the coil, 2 and the capacitors and 3 is the varistor.

When a noise input A shown in FIG. 5 is impressed on these circuits, output characteristics 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 varistor 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 90.800-99.996 mol % of SrTiO.sub.3 and as metal oxides for semiconductorization acceleration 0.001-0.200 mol % of Nb.sub.2 O.sub.5 and 0.001-5.000 mol % of Ta.sub.2 O.sub.5, and is characterized by containing 0.001-2.000 mol % in the form of oxide of at least one kind of element selected from the group consisting of Ga, Pt, Tl, Si, Ti, Cs, Au, S, Be, Al, Ca, Cd, In, Ba, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn, Sb and.

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 varistors 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 Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 as semi-conductorization accelerating agent, and by further adding MnO.sub.2 and appropriate amount of other additives; hereafter the present invention is described with respect to embodiments.

EXAMPLE 1

After measuring SrTiO.sub.3, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, MnO.sub.2 and Tl.sub.2 O 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, polyvinylalcohol), 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 atmosphere (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 dired 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 and electrodes 5, 6 are formed by using a conductive metal such as Ag. 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 %) Characteristic valueNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 MnO.sub.2 Tl.sub.2 O V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________ 1* 99.795 0.100 0 0.100 0.005 1240 3.5 1 .times. 10.sup.3 5.4 2* 99.300 0.100 0 0.500 0.100 1460 5.7 1 .times. 10.sup.3 10.9 3* 99.899 0.100 0.001 0 0 90 3.0 1 .times. 10.sup.3 4.2 4* 99.898 0.100 0.001 0 0.001 110 4.2 1 .times. 10.sup.3 3.6 5* 99.799 0.100 0.001 0 0.100 117 4.9 2 .times. 10.sup.3 3.0 6* 97.899 0.100 0.001 0 2.000 135 5.6 2 .times. 10.sup.3 3.0 7* 96.899 0.100 0.001 0 3.000 175 5.5 2 .times. 10.sup.3 4.6 8* 99.898 0.100 0.001 0.001 0 100 5.7 4 .times. 10.sup.3 4.19 99.897 0.100 0.001 0.001 0.001 120 8.6 8 .times. 10.sup.3 3.510 99.798 0.100 0.001 0.001 0.100 128 9.7 9 .times. 10.sup.3 3.011 97.799 0.100 0.001 0.001 2.000 142 9.7 9 .times. 10.sup.3 2.912* 96.799 0.100 0.001 0.001 3.000 164 9.5 5 .times. 10.sup.3 3.913* 98.899 0.100 0.001 1.000 0 150 8.2 4 .times. 10.sup.3 4.514 98.898 0.100 0.001 1.000 0.001 157 8.7 8 .times. 10.sup.3 4.015 98.799 0.100 0.001 1.000 0.100 167 9.6 9 .times. 10.sup.3 3.416 96.899 0.100 0.001 1.000 2.000 173 9.8 1.0 .times. 10.sup.4 3.017* 95.899 0.100 0.001 1.000 3.000 182 9.2 6 .times. 10.sup.3 7.118* 97.899 0.100 0.001 2.000 0 190 8.8 5 .times. 10.sup.3 10.119 97.898 0.100 0.001 2.000 0.001 198 8.0 9 .times. 10.sup.3 10.120 97.799 0.100 0.001 2.000 0.100 202 8.7 9 .times. 10.sup.3 9.321 95.899 0.100 0.001 2.000 2.000 204 8.7 1.0 .times. 10.sup.4 8.922* 94.899 0.100 0.001 2.000 3.000 255 7.9 5 .times. 10.sup.3 7.823* 98.899 0.100 1.000 0.001 0 90 8.0 4 .times. 10.sup.3 4.024 98.898 0.100 1.000 0.001 0.001 100 9.2 8 .times. 10.sup.3 2.725 98.799 0.100 1.000 0.001 0.100 111 11.3 9 .times. 10.sup.3 2.326 96.899 0.100 1.000 0.001 2.000 127 11.6 1.1 .times. 10.sup.4 2.327* 95.899 0.100 1.000 0.001 3.000 156 9.1 6 .times. 10.sup.3 6.328* 97.900 0.100 1.000 1.000 0 130 8.2 5 .times. 10.sup.3 4.229 97.899 0.100 1.000 1.000 0.001 147 9.2 8 .times. 10.sup.3 2.930 97.800 0.100 1.000 1.000 0.100 156 12.0 9 .times. 10.sup.3 2.531 95.900 0.100 1.000 1.000 2.000 162 11.5 1.1 .times. 10.sup.4 2.332* 94.900 0.100 1.000 1.000 3.000 175 9.0 7 .times. 10.sup.3 5.433* 96.900 0.100 1.000 2.000 0 180 8.0 6 .times. 10.sup.3 10.034 96.899 0.100 1.000 2.000 0.001 198 8.0 7 .times. 10.sup.3 9.535 96.800 0.100 1.000 2.000 0.100 213 8.1 7 .times. 10.sup.3 9.036 94.900 0.100 1.000 2.000 2.000 233 8.5 7 .times. 10.sup.3 8.937* 93.900 0.100 1.000 2.000 3.000 260 7.9 8 .times. 10.sup.3 8.838* 94.899 0.100 5.000 0.001 0 75 7.2 7 .times. 10.sup.3 3.839 94.898 0.100 5.000 0.001 0.001 85 7.7 7 .times. 10.sup.3 3.040 94.799 0.100 5.000 0.001 0.100 96 9.3 8 .times. 10.sup.3 2.541 92.899 0.100 5.000 0.001 2.000 112 9.8 9 .times. 10.sup.3 2.442* 91.899 0.100 5.000 0.001 3.000 127 9.0 5 .times. 10.sup.3 3.543* 93.900 0.100 5.000 1.000 0 82 7.6 7 .times. 10.sup.3 3.944 93.899 0.100 5.000 1.000 0.001 94 8.4 9 .times. 10.sup.3 2.645 93.800 0.100 5.000 1.000 0.100 112 10.2 1 .times. 10.sup.4 2.546 91.900 0.100 5.000 1.000 2.000 115 10.1 1.1 .times. 10.sup.4 2.547* 90.900 0.100 5.000 1.000 3.000 139 9.5 6 .times. 10.sup.3 4.348* 92.900 0.100 5.000 2.000 0 95 8.4 7 .times. 10.sup.3 9.449* 92.899 0.100 5.000 2.000 0.001 121 9.1 7 .times. 10.sup.3 9.350* 92.800 0.100 5.000 2.000 0.100 131 10.2 8 .times. 10.sup.3 9.051* 90.900 0.100 5.000 2.000 2.000 138 10.2 8 .times. 10.sup.3 8.652* 89.900 0.100 5.000 2.000 3.000 195 8.5 4 .times. 10.sup.3 9.253* 92.899 0.100 7.000 0.001 0 40 4.0 6 .times. 10.sup.3 6.254* 92.898 0.100 7.000 0.001 0.001 60 4.3 6 .times. 10.sup.3 6.155* 92.799 0.100 7.000 0.001 0.100 63 4.3 6 .times. 10.sup.3 5.956* 90.899 0.100 7.000 0.001 2.000 69 4.5 6 .times. 10.sup.3 5.957* 89.899 0.100 7.000 0.001 3.000 102 4.7 5 .times. 10.sup.3 7.858* 91.900 0.100 7.000 1.000 0 49 4.4 6 .times. 10.sup.3 10.259* 91.899 0.100 7.000 1.000 0.001 75 4.8 6 .times. 10.sup.3 10.160* 91.800 0.100 7.000 1.000 0.100 81 5.2 6 .times. 10.sup.3 10.061* 89.900 0.100 7.000 1.000 2.000 93 5.8 5 .times. 10.sup.3 9.862* 88.900 0.100 7.000 1.000 3.000 124 5.0 4 .times. 10.sup.3 9.963* 95.800 0.100 1.000 3.000 0.100 211 4.2 5 .times. 10.sup.3 23.164* 92.900 0.100 1.000 3.000 3.000 244 5.3 4 .times. 10.sup.3 21.0__________________________________________________________________________ *Comparison sample

Herein, evaluation of characteristics of the elements as varistor 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 varistor and .alpha. is a non-linearity exponent). Since accurate measurement of C is difficult, in the present invention, characteristic assessment as varistor is made by the value of varistor voltage for unit thickness when 1 mA of varistor 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 varistor voltage when a varistor current of 10 mA is flowed and V.sub.1 mA is a varistor voltage when varistor current of 1 mA is flowed).

And characteristic assessment as the capacitors are made by a dielectric constant .epsilon. 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, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, MnO.sub.2 and Y.sub.2 O.sub.5 are made in a composition ratio shown in the below-mentioned Table 2, and mixing, forming and firings are carried out 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 %) Characteristic valueNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 MnO.sub.2 Y.sub.2 O.sub.3 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________ 1* 99.795 0.100 0 0.100 0.005 1350 3.5 1 .times. 10.sup.3 5.3 2* 99.300 0.100 0 0.500 0.100 1530 5.2 3 .times. 10.sup.3 9.2 3* 99.899 0.100 0.001 0 0 90 3.0 1 .times. 10.sup.3 4.2 4* 99.898 0.100 0.001 0 0.001 102 4.0 1 .times. 10.sup.3 2.7 5* 99.799 0.100 0.001 0 0.100 110 4.7 2 .times. 10.sup.3 2.0 6* 97.899 0.100 0.001 0 2.000 130 5.7 3 .times. 10.sup.3 2.1 7* 96.899 0.100 0.001 0 3.000 162 5.8 2 .times. 10.sup.3 2.2 8* 99.898 0.100 0.001 0.001 0 100 5.7 4 .times. 10.sup.3 4.19 99.897 0.100 0.001 0.001 0.001 105 8.4 8 .times. 10.sup. 3 2.610 99.798 0.100 0.001 0.001 0.100 114 9.5 9 .times. 10.sup.3 2.011 97.799 0.100 0.001 0.001 2.000 138 9.7 1 .times. 10.sup.4 2.012* 96.799 0.100 0.001 0.001 3.000 152 10.1 6 .times. 10.sup.3 2.813* 98.899 0.100 0.001 1.000 0 150 8.2 4 .times. 10.sup.3 4.514 98.898 0.100 0.001 1.000 0.001 155 8.5 9 .times. 10.sup.3 3.115 98.799 0.100 0.001 1.000 0.100 164 9.4 1 .times. 10.sup.4 2.616 96.899 0.100 0.001 1.000 2.000 173 10.0 1.1 .times. 10.sup.4 2.217* 95.899 0.100 0.001 1.000 3.000 178 10.4 6 .times. 10.sup.3 2.018* 97.899 0.100 0.001 2.000 0 190 8.8 5 .times. 10.sup.3 10.119 97.898 0.100 0.001 2.000 0.001 210 8.7 9 .times. 10.sup.3 9.020 97.799 0.100 0.001 2.000 0.100 218 9.3 1.1 .times. 10.sup.4 8.921 95.899 0.100 0.001 2.000 2.000 232 10.2 1.1 .times. 10.sup.4 7.922* 94.899 0.100 0.001 2.000 3.000 260 10.0 8 .times. 10.sup.3 6.823* 98.899 0.100 1.000 0.001 0 90 8.0 4 .times. 10.sup.3 4.024 98.898 0.100 1.000 0.001 0.001 95 8.9 9 .times. 10.sup.3 2.925 98.799 0.100 1.000 0.001 0.100 103 11.2 1.0 .times. 10.sup.4 2.026 96.899 0.100 1.000 0.001 2.000 125 11.8 1.1 .times. 10.sup.4 2.027* 95.899 0.100 1.000 0.001 3.000 149 10.1 7 .times. 10.sup.3 2.128* 97.900 0.100 1.000 1.000 0 130 8.2 5 .times. 10.sup.3 4.229 97.899 0.100 1.000 1.000 0.001 140 9.0 9 .times. 10.sup.3 3.030 97.800 0.100 1.000 1.000 0.100 149 11.8 1.2 .times. 10.sup.4 2.231 95.900 0.100 1.000 1.000 2.000 152 11.6 1.4 .times. 10.sup.4 2.032* 94.900 0.100 1.000 1.000 3.000 168 9.5 6 .times. 10.sup.3 2.033* 96.900 0.100 1.000 2.000 0 180 8.0 6 .times. 10.sup.3 10.034 96.899 0.100 1.000 2.000 0.001 192 8.3 8 .times. 10.sup.3 9.035 96.800 0.100 1.000 2.000 0.100 209 8.4 1.1 .times. 10.sup.4 8.936 94.900 0.100 1.000 2.000 2.000 213 8.9 1.4 .times. 10.sup.4 8.837* 93.900 0.100 1.000 2.000 3.000 255 9.1 5 .times. 10.sup.3 8.338* 94.899 0.100 5.000 0.001 0 75 7.2 7 .times. 10.sup.3 3.839 94.898 0.100 5.000 0.001 0.001 84 7.4 9 .times. 10.sup.3 2.740 94.799 0.100 5.000 0.001 0.100 95 9.0 9 .times. 10.sup.3 2.441 92.899 0.100 5.000 0.001 2.000 112 10.0 1.1 .times. 10.sup.4 2.042* 91.899 0.100 5.000 0.001 3.000 121 10.2 6 .times. 10.sup.3 2.043* 93.900 0.100 5.000 1.000 0 82 7.6 7 .times. 10.sup.3 3.944 93.899 0.100 5.000 1.000 0.001 95 8.1 1 .times. 10.sup.4 2.845 93.800 0.100 5.000 1.000 0.100 102 9.9 1.2 .times. 10.sup.4 2.646 91.900 0.100 5.000 1.000 2.000 109 10.2 1.1 .times. 10.sup.4 2.347* 90.900 0.100 5.000 1.000 3.000 123 10.5 5 .times. 10.sup.3 2.248* 92.900 0.100 5.000 2.000 0 95 8.4 7 .times. 10.sup.3 9.449 92.899 0.100 5.000 2.000 0.001 108 9.0 8 .times. 10.sup.3 9.350 92.800 0.100 5.000 2.000 0.100 119 10.8 9 .times. 10.sup.3 8.051 90.900 0.100 5.000 2.000 2.000 124 12.0 1 .times. 10.sup.4 8.052* 89.900 0.100 5.000 2.000 3.000 148 10.1 7 .times. 10.sup.3 7.253* 92.899 0.100 7.000 0.001 0 40 4.0 6 .times. 10.sup.3 6.254* 92.898 0.100 7.000 0.001 0.001 53 4.2 7 .times. 10.sup.3 6.155* 92.799 0.100 7.000 0.001 0.100 56 4.3 8 .times. 10.sup.3 5.856* 90.899 0.100 7.000 0.001 2.000 64 6.0 8 .times. 10.sup.3 6.057* 89.899 0.100 7.000 0.001 3.000 71 5.3 7 .times. 10.sup.3 5.958* 91.900 0.100 7.000 1.000 0 49 4.4 6 .times. 10.sup.3 10.259* 91.988 0.100 7.000 1.000 0.001 60 4.4 8 .times. 10.sup.3 9.260* 91.800 0.100 7.000 1.000 0.100 64 5.0 8 .times. 10.sup.3 8.961* 89.900 0.100 7.000 1.000 2.000 84 7.0 7 .times. 10.sup.3 9.062* 88.900 0.100 7.000 1.000 3.000 92 6.0 7 .times. 10.sup.3 9.163* 95.800 0.100 1.000 3.000 0.100 194 7.2 4 .times. 10.sup.3 19.264* 92.900 0.100 1.000 3.000 3.000 281 6.6 3 .times. 10.sup.3 18.0__________________________________________________________________________ *Comparison sample

EXAMPLE 3

SrTiO.sub.3, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, MnO.sub.2 and BaO are made in a composition ratio shown in the below-mentioned Table 3, and mixing, forming and firings are carried out 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 %) Characteristic valueNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 MnO.sub.2 BaO V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________ 1* 99.795 0.100 0 0.100 0.005 1300 3.4 1 .times. 10.sup.3 5.2 2* 99.300 0.100 0 0.500 0.100 1550 5.0 2 .times. 10.sup.3 8.3 3* 99.899 0.100 0.001 0 0 90 3.0 1 .times. 10.sup.3 4.2 4* 99.898 0.100 0.001 0 0.001 98 4.1 1 .times. 10.sup.3 2.8 5* 99.799 0.100 0.001 0 0.100 105 4.8 3 .times. 10.sup.3 2.1 6* 97.899 0.100 0.001 0 2.000 121 5.6 3 .times. 10.sup.3 2.0 7* 96.899 0.100 0.001 0 3.000 155 5.9 1 .times. 10.sup.3 1.9 8* 99.898 0.100 0.001 0.001 0 100 5.7 4 .times. 10.sup.3 4.19 99.897 0.100 0.001 0.001 0.001 102 8.6 8 .times. 10.sup.3 2.710 99.798 0.100 0.001 0.001 0.100 111 9.8 8 .times. 10.sup.3 2.011 97.799 0.100 0.001 0.001 2.000 135 10.5 9 .times. 10.sup.3 2.012* 96.799 0.100 0.001 0.001 3.000 150 11.2 5 .times. 10.sup.3 2.013* 98.899 0.100 0.001 1.000 0 150 8.2 4 .times. 10.sup.3 4.514 98.898 0.100 0.001 1.000 0.001 152 8.9 8 .times. 10.sup.3 3.015 98.799 0.100 0.001 1.000 0.100 160 10.1 9 .times. 10.sup.3 2.616 96.899 0.100 0.001 1.000 2.000 168 11.4 1 .times. 10.sup.4 2.317* 95.899 0.100 0.001 1.000 3.000 172 11.8 5 .times. 10.sup.3 2.218* 97.899 0.100 0.001 2.000 0 190 8.8 5 .times. 10.sup.3 10.119 97.898 0.100 0.001 2.000 0.001 205 9.0 9 .times. 10.sup.3 9.220 97.799 0.100 0.001 2.000 0.100 215 10.4 1.1 .times. 10.sup.4 9.121 95.899 0.100 0.001 2.000 2.000 230 11.9 1 .times. 10.sup.4 8.022* 94.899 0.100 0.001 2.000 3.000 254 10.5 7 .times. 10.sup. 3 6.923* 98.899 0.100 1.000 0.001 0 90 8.0 4 .times. 10.sup.3 4.024 98.898 0.100 1.000 0.001 0.001 93 9.1 8 .times. 10.sup.3 2.825 98.799 0.100 1.000 0.001 0.100 100 11.4 9 .times. 10.sup.3 2.626 96.899 0.100 1.000 0.001 2.000 120 12.0 1 .times. 10.sup.4 2.527* 95.899 0.100 1.000 0.001 3.000 140 10.1 6 .times. 10.sup.3 2.328* 97.900 0.100 1.000 1.000 0 130 8.2 5 .times. 10.sup.3 4.229 97.899 0.100 1.000 1.000 0.001 135 9.3 9 .times. 10.sup.3 2.930 97.800 0.100 1.000 1.000 0.100 148 12.1 1.1 .times. 10.sup.4 2.131 95.900 0.100 1.000 1.000 2.000 150 11.8 1.3 .times. 10.sup.4 2.132* 94.900 0.100 1.000 1.000 3.000 164 10.0 6 .times. 10.sup.3 2.033* 96.900 0.100 1.000 2.000 0 180 8.0 6 .times. 10.sup.3 10.034 96.899 0.100 1.000 2.000 0.001 190 8.5 8 .times. 10.sup.3 9.235 96.800 0.100 1.000 2.000 0.100 204 8.9 1 .times. 10.sup.4 9.036 94.900 0.100 1.000 2.000 2.000 210 9.4 1.3 .times. 10.sup.4 8.837* 93.900 0.100 1.000 2.000 3.000 245 9.5 8 .times. 10.sup.3 8.138* 94.899 0.100 5.000 0.001 0 75 7.2 7 .times. 10.sup.3 3.839 94.898 0.100 5.000 0.001 0.001 81 7.9 9 .times. 10.sup.3 2.940 94.799 0.100 5.000 0.001 0.100 85 9.9 1 .times. 10.sup.4 2.541 92.899 0.100 5.000 0.001 2.000 100 10.4 1.2 .times. 10.sup.4 2.142* 91.899 0.100 5.000 0.001 3.000 115 11.0 6 .times. 10.sup.3 2.043* 93.900 0.100 5.000 1.000 0 82 7.6 7 .times. 10.sup.3 3.944 93.899 0.100 5.000 1.000 0.001 85 8.3 9 .times. 10.sup.3 2.945 93.800 0.100 5.000 1.000 0.100 97 10.1 1.1 .times. 10.sup.4 2.646 91.900 0.100 5.000 1.000 2.000 108 11.2 1 .times. 10.sup.4 2.247* 90.900 0.100 5.000 1.000 3.000 120 10.7 5 .times. 10.sup.3 2.148* 92.900 0.100 5.000 2.000 0 95 8.4 7 .times. 10.sup.3 9.449 92.899 0.100 5.000 2.000 0.001 102 9.2 8 .times. 10.sup.3 9.350 92.800 0.100 5.000 2.000 0.100 114 11.0 1 .times. 10.sup.4 8.151 90.900 0.100 5.000 2.000 2.000 123 12.3 1 .times. 10.sup.4 8.052* 89.900 0.100 5.000 2.000 3.000 147 10.4 7 .times. 10.sup.3 7.453* 92.899 0.100 7.000 0.001 0 40 4.0 6 .times. 10.sup.3 6.254* 92.898 0.100 7.000 0.001 0.001 43 4.4 7 .times. 10.sup.3 6.055* 92.799 0.100 7.000 0.001 0.100 49 4.5 8 .times. 10.sup.3 5.856* 90.899 0.100 7.000 0.001 2.000 52 6.2 9 .times. 10.sup.3 5.957* 89.899 0.100 7.000 0.001 3.000 69 5.8 7 .times. 10.sup.3 5.858* 91.900 0.100 7.000 1.000 0 49 4.4 6 .times. 10.sup.3 10.259* 91.899 0.100 7.000 1.000 0.001 55 4.8 8 .times. 10.sup.3 9.460* 91.800 0.100 7.000 1.000 0.100 62 5.5 8 .times. 10.sup.3 9.161* 89.900 0.100 7.000 1.000 2.000 84 7.2 8 .times. 10.sup.3 9.062* 88.900 0.100 7.000 1.000 3.000 93 6.1 7 .times. 10.sup.3 8.563* 95.800 0.100 1.000 3.000 0.100 131 8.2 5 .times. 10.sup.3 19.764* 92.900 0.100 1.000 3.000 3.000 249 9.1 4 .times. 10.sup.3 18.0__________________________________________________________________________ *Comparison sample

EXAMPLE 4

SrTiO.sub.3, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, MnO.sub.2 and HfO.sub.2 are made in a composition ratio shown in the below-mentioned Table 4, and mixing, forming and firings are carried out 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 %) Characteristic valueNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 MnO.sub.2 HfO.sub.2 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________ 1* 99.795 0.100 0 0.100 0.005 1220 3.5 1 .times. 10.sup.3 6.4 2* 99.300 0.100 0 0.500 0.100 1470 5.6 2 .times. 10.sup.3 11.8 3* 99.899 0.100 0.001 0 0 90 3.0 1 .times. 10.sup.3 4.2 4* 99.898 0.100 0.001 0 0.001 130 4.2 1 .times. 10.sup.3 3.9 5* 99.799 0.100 0.001 0 0.100 135 4.9 2 .times. 10.sup.3 3.3 6* 97.899 0.100 0.001 0 2.000 137 5.5 4 .times. 10.sup.3 3.0 7* 96.899 0.100 0.001 0 3.000 194 5.4 3 .times. 10.sup.3 4.5 8* 99.898 0.100 0.001 0.001 0 100 5.7 4 .times. 10.sup.3 4.19 99.897 0.100 0.001 0.001 0.001 135 8.6 8 .times. 10.sup.3 3.710 99.798 0.100 0.001 0.001 0.100 142 9.7 9 .times. 10.sup.3 3.211 97.799 0.100 0.001 0.001 2.000 160 9.8 9 .times. 10.sup.3 2.912* 96.799 0.100 0.001 0.001 3.000 184 9.4 5 .times. 10.sup.3 3.813* 98.899 0.100 0.001 1.000 0 150 8.2 4 .times. 10.sup.3 4.514 98.898 0.100 0.001 1.000 0.001 172 8.8 9 .times. 10.sup.3 4.115 98.799 0.100 0.001 1.000 0.100 181 9.7 9 .times. 10.sup.3 3.516 96.899 0.100 0.001 1.000 2.000 185 9.9 1.1 .times. 10.sup.4 3.017* 95.899 0.100 0.001 1.000 3.000 202 9.1 6 .times. 10.sup.3 7.218* 97.899 0.100 0.001 2.000 0 190 8.8 5 .times. 10.sup.3 10.119 97.898 0.100 0.001 2.000 0.001 208 8.0 9 .times. 10.sup.3 10.020 97.799 0.100 0.001 2.000 0.100 219 8.6 1 .times. 10.sup.4 9.221 95.899 0.100 0.001 2.000 2.000 224 8.5 1.1 .times. 10.sup.4 8.922* 94.899 0.100 0.001 2.000 3.000 275 7.8 6 .times. 10.sup.3 7.923* 98.899 0.100 1.000 0.001 0 90 8.0 4 .times. 10.sup.3 4.024 98.898 0.100 1.000 0.001 0.001 114 9.2 9 .times. 10.sup.3 2.825 98.799 0.100 1.000 0.001 0.100 127 11.3 1 .times. 10.sup.4 2.326 96.899 0.100 1.000 0.001 2.000 141 11.5 1.1 .times. 10.sup.4 2.327* 95.899 0.100 1.000 0.001 3.000 176 9.0 6 .times. 10.sup.3 6.428* 97.900 0.100 1.000 1.000 0 130 8.2 5 .times. 10.sup.3 4.229 97.899 0.100 1.000 1.000 0.001 159 9.2 9 .times. 10.sup.3 3.030 97.800 0.100 1.000 1.000 0.100 169 12.0 9 .times. 10.sup.3 2.631 95.900 0.100 1.000 1.000 2.000 175 11.4 1.1.times. 10.sup.4 2.332* 94.900 0.100 1.000 1.000 3.000 200 9.1 7 .times. 10.sup.3 5.533* 96.900 0.100 1.000 2.000 0 180 8.0 6 .times. 10.sup.3 10.034 96.899 0.100 1.000 2.000 0.001 205 8.0 7 .times. 10.sup.3 9.635 96.800 0.100 1.000 2.000 0.100 221 8.0 7 .times. 10.sup.3 9.136 94.900 0.100 1.000 2.000 2.000 245 8.1 8 .times. 10.sup.3 8.937* 93.900 0.100 1.000 2.000 3.000 280 6.8 9 .times. 10.sup.3 8.938* 94.899 0.100 5.000 0.001 0 75 7.2 7 .times. 10.sup.4 3.839 94.898 0.100 5.000 0.001 0.001 100 7.8 7 .times. 10.sup.3 3.240 94.799 0.100 5.000 0.001 0.100 106 9.4 8 .times. 10.sup.3 2.741 92.899 0.100 5.000 0.001 2.000 130 9.8 9 .times. 10.sup.3 2.442* 91.899 0.100 5.000 0.001 3.000 147 8.9 4 .times. 10.sup.3 3.643* 93.900 0.100 5.000 1.000 0 82 7.6 7 .times. 10.sup.3 3.944 93.899 0.100 5.000 1.000 0.001 109 8.5 9 .times. 10.sup.3 2.845 93.800 0.100 5.000 1.000 0.100 125 10.3 1.1 .times. 10.sup.4 2.746 91.900 0.100 5.000 1.000 2.000 135 10.2 1.2 .times. 10.sup.4 2.547* 90.900 0.100 5.000 1.000 3.000 169 9.3 6 .times. 10.sup.3 4.448* 92.900 0.100 5.000 2.000 0 95 8.4 7 .times. 10.sup.3 9.449* 92.899 0.100 5.000 2.000 0.001 135 9.0 7 .times. 10.sup. 3 9.450* 92.800 0.100 5.000 2.000 0.100 142 10.1 8 .times. 10.sup.3 9.151* 90.900 0.100 5.000 2.000 2.000 158 10.0 8 .times. 10.sup.3 8.652* 89.900 0.100 5.000 2.000 3.000 211 8.2 4 .times. 10.sup.3 9.353* 92.899 0.100 7.000 0.001 0 40 4.0 6 .times. 10.sup.3 6.254* 92.898 0.100 7.000 0.001 0.001 71 4.4 7 .times. 10.sup.3 6.255* 92.799 0.100 7.000 0.001 0.100 78 4.3 6 .times. 10.sup.3 6.056* 90.899 0.100 7.000 0.001 2.000 89 4.3 6 .times. 10.sup.3 5.957* 89.899 0.100 7.000 0.001 3.000 128 4.0 6 .times. 10.sup.3 7.958* 91.900 0.100 7.000 1.000 0 49 4.4 6 .times. 10.sup.3 10.259* 91.899 0.100 7.000 1.000 0.001 88 4.8 7 .times. 10.sup.3 10.260* 91.800 0.100 7.000 1.000 0.100 91 5.1 6 .times. 10.sup.3 10.161* 89.900 0.100 7.000 1.000 2.000 104 5.0 6 .times. 10.sup.3 10.062* 88.900 0.100 7.000 1.000 3.000 144 4.2 4 .times. 10.sup.3 10.063* 95.800 0.100 1.000 3.000 0.100 215 6.2 4 .times. 10.sup.3 28.064* 92.900 0.100 1.000 3.000 3.000 272 5.0 4 .times. 10.sup.3 22.4__________________________________________________________________________ *Comparison sample

EXAMPLE 5

SrTiO.sub.3, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, MnO.sub.2 and ZrO.sub.2 are made in a composition ratio shown in the below-mentioned Table 5, and mixing, forming and firings are carried out in a similar operation as the above-mentioned Example 1, and measurements are made in the similar conditions and results are shown in Table 5.

TABLE 5__________________________________________________________________________Sample Composition ratio (mol %) Characteristic valueNo. SrTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 MnO.sub.2 ZrO.sub.2 V.sub.1 mA/mm (V) .alpha. .epsilon. tan .delta. (%)__________________________________________________________________________ 1* 99.795 0.100 0 0.100 0.005 1340 3.4 1 .times. 10.sup.3 6.4 2* 99.300 0.100 0 0.500 0.100 1520 5.5 2 .times. 10.sup.3 11.4 3* 99.899 0.100 0.001 0 0 90 3.0 1 .times. 10.sup.3 4.2 4* 99.898 0.100 0.001 0 0.001 105 4.1 1 .times. 10.sup.3 3.7 5* 99.799 0.100 0.001 0 0.100 112 4.8 2 .times. 10.sup.3 3.0 6* 97.899 0.100 0.001 0 2.000 134 5.6 2 .times. 10.sup.3 3.0 7* 96.899 0.100 0.001 0 3.000 174 5.7 3 .times. 10.sup.3 4.5 8* 99.898 0.100 0.001 0.001 0 100 5.7 4 .times. 10.sup.3 4.19 99.897 0.100 0.001 0.001 0.001 115 8.5 7 .times. 10.sup.3 3.610 99.798 0.100 0.001 0.001 0.100 123 9.6 9 .times. 10.sup.3 3.011 97.799 0.100 0.001 0.001 2.000 141 9.7 9 .times. 10.sup.3 2.912* 96.799 0.100 0.001 0.001 3.000 163 10.0 5 .times. 10.sup.3 3.813* 98.899 0.100 0.001 1.000 0 150 8.2 4 .times. 10.sup.3 4.514 98.898 0.100 0.001 1.000 0.001 152 8.6 8 .times. 10.sup.3 4.115 98.799 0.100 0.001 1.000 0.100 163 9.5 9 .times. 10.sup.3 3.516 96.899 0.100 0.001 1.000 2.000 172 9.9 1 .times. 10.sup.4 3.017* 95.899 0.100 0.001 1.000 3.000 181 9.4 6 .times. 10.sup.3 7.018* 97.899 0.100 0.001 2.000 0 190 8.8 5 .times. 10.sup.3 10.119 97.898 0.100 0.001 2.000 0.001 193 8.2 9 .times. 10.sup.3 10.020 97.799 0.100 0.001 2.000 0.100 198 9.0 1 .times. 10.sup.4 9.221 95.899 0.100 0.001 2.000 2.000 203 9.7 1.1 .times. 10.sup.4 8.722* 94.899 0.100 0.001 2.000 3.000 254 9.7 6 .times. 10.sup.3 7.423* 98.899 0.100 1.000 0.001 0 90 8.0 4 .times. 10.sup.3 4.024 98.898 0.100 1.000 0.001 0.001 97 9.1 8 .times. 10.sup.3 2.825 97.799 0.100 1.000 0.001 0.100 104 11.2 9 .times. 10.sup.3 2.426 96.899 0.100 1.000 0.001 2.000 126 11.7 1 .times. 10.sup.4 2.327* 95.899 0.100 1.000 0.001 3.000 155 10.0 6 .times. 10.sup.3 6.128* 97.900 0.100 1.000 1.000 0 130 8.2 5 .times. 10.sup.3 4.229 97.899 0.100 1.000 1.000 0.001 143 9.1 9 .times. 10.sup.3 3.030 97.800 0.100 1.000 1.000 0.100 151 11.9 1 .times. 10.sup.4 2.431 95.900 0.100 1.000 1.000 2.000 155 11.5 1.1 .times. 10.sup.4 2.232* 94.900 0.100 1.000 1.000 3.000 174 9.4 7 .times. 10.sup.3 5.433* 96.900 0.100 1.000 2.000 0 180 8.0 6 .times. 10.sup.3 10.034 96.899 0.100 1.000 2.000 0.001 194 8.1 7 .times. 10.sup.3 9.435 96.800 0.100 1.000 2.000 0.100 209 8.2 7 .times. 10.sup.3 8.936 94.900 0.100 1.000 2.000 2.000 231 8.7 8 .times. 10.sup.3 8.837* 93.900 0.100 1.000 2.000 3.000 258 8.9 5 .times. 10.sup.3 8.838* 94.899 0.100 5.000 0.001 0 75 7.2 7 .times. 10.sup.3 3.839 94.898 0.100 5.000 0.001 0.001 83 7.6 8 .times. 10.sup.3 2.940 94.799 0.100 5.000 0.001 0.100 94 9.2 9 .times. 10.sup.3 2.441 92.899 0.100 5.000 0.001 2.000 110 9.9 1 .times. 10.sup.4 2.342* 91.899 0.100 5.000 0.001 3.000 126 10.0 6 .times. 10.sup.3 3.643* 93.900 0.100 5.000 1.000 0 82 7.6 7 .times. 10.sup.3 3.944 93.899 0.100 5.000 1.000 0.001 93 8.3 9 .times. 10.sup.3 2.745 93.800 0.100 5.000 1.000 0.100 100 10.1 1 .times. 10.sup.4 2.646 91.900 0.100 5.000 1.000 2.000 107 10.0 9 .times. 10.sup.3 2.647* 90.900 0.100 5.000 1.000 3.000 134 9.7 5 .times. 10.sup.3 4.248* 92.900 0.100 5.000 2.000 0 95 8.4 7 .times. 10.sup.3 9.449* 92.899 0.100 5.000 2.000 0.001 112 9.0 7 .times. 10.sup.3 9.450* 92.800 0.100 5.000 2.000 0.100 124 10.1 7 .times. 10.sup.3 9.151* 90.900 0.100 5.000 2.000 2.000 128 10.3 8 .times. 10.sup.3 8.552* 89.900 0.100 5.000 2.000 3.000 192 9.1 5 .times. 10.sup.3 9.053* 92.899 0.100 7.000 0.001 0 40 4.0 6 .times. 10.sup.3 6.254* 92.898 0.100 7.000 0.001 0.001 58 4.5 6 .times. 10.sup.3 6.055* 92.799 0.100 7.000 0.001 0.100 62 4.6 6 .times. 10.sup.3 5.856* 90.899 0.100 7.000 0.001 2.000 69 6.2 7 .times. 10.sup.3 5.857* 89.899 0.100 7.000 0.001 3.000 99 4.9 5 .times. 10.sup.3 7.158* 91.900 0.100 7.000 1.000 0 49 4.4 6 .times. 10.sup.3 10.259* 91.899 0.100 7.000 1.000 0.001 74 4.9 6 .times. 10.sup.3 10.060* 91.800 0.100 7.000 1.000 0.100 80 5.5 6 .times. 10.sup.3 9.961* 89.900 0.100 7.000 1.000 2.000 91 6.8 6 .times. 10.sup.3 9.862* 88.900 0.100 7.000 1.000 3.000 122 5.3 5 .times. 10.sup.3 9.963* 95.800 0.100 1.000 3.000 0.100 197 6.5 4 .times. 10.sup.3 20.564* 92.900 0.100 1.000 3.000 3.000 227 6.3 4 .times. 10.sup.3 18.4__________________________________________________________________________ *Comparison sample

As shown by Examples 1 to 5, Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 dissolve as solid solution into the crystal having SrTiO.sub.3 as host material at the reduced firing and thereby to reduce specific resistance of the fired body by about 1.0 .OMEGA.cm by atomic valency controlling, and therefore, by refiring in the air it shows varistor characteristics such that high resitance layers are formed at the grain boundaries of the fired bodies.

And, Nb.sub.2 O.sub.5 is contained in TiO.sub.2 in the material as inclusion, and is contained in 0.001-0.200 mol % in the raw material usually to be industrically refined. In case the SrTiO.sub.3 is semiconductorized only with Nb.sub.2 O.sub.5 the specific resistance becomes rather high, and the characteristic is unstable though it shows the varistor characteristics. But by addition of Ta.sub.2 O.sub.5 to Nb.sub.2 O.sub.5, the specific resistance can be lowered, and stable characteristics are obtainable. When the added amount of Ta.sub.2 O.sub.5 is too much, dissolution as solid solution of other additives is hindered, and accordingly 0.001-5.000 mol % of it is appropriate.

By making segregation at granule boundaries by addition of MnO.sub.2, the granule boundaries is changed to a high resistance value and the energy barrier of the granule boundaries. Therefore, by the addition of MnO.sub.2, the non-linearity exponent .alpha. becomes large and at the same time the varistor voltage becomes high.

Besides, by the addition of MnO.sub.2 the high resistance region of the granule boundaries expands, and accordingly this means that thickness of the insulation layer increases, and thereby the dielectric constant decreases.

Since MnO.sub.2 takes plural valency, there is a possibility of producing hopping conduction between different Mn valency. Therefore, when the amount of addition of MnO.sub.2 increases the tan .delta. becomes large, to induce a cause of deterioration of the characteristic. Accordingly, as the amount of addition of MnO.sub.2, 0.001-2.000 mol % is appropriate. When La, Cu, Y, Mo, Pb and W are added, for the amount of MnO.sub.2, a range of 0.001 to 0.01 mole % is desirable for Na an amount of 0.001 to 0.02 mol % is desirable.

When at least one element selected from the group consisting of Ga, Pt, Tl, Si, Ti, Li, La, Cu, Y, Cs, Au, Mo, S, Be, Al, Na, K, Ca, Cd, In, Ba, Pb, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn, Sb and W is added at the same time, it is possible to increase the dielectric constant and decrease the tan .delta., without changing the non-linearity exponent .alpha. increased by MnO.sub.2, to greatly improve the characteristic, but the dielectric constant becomes small when the amount of addition becomes much; and accordingly 0.001-2.000 mol % is appropriate.

Though in the examples, only the cases where Ga, Pt, Tl, Si, Ti, Li, La, Cu, Y, Cs, Au, Mo, S, Be, Al, Na, K, Ca, Cd, In, Ba, Pb, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn, Sb and W are added each as simple substance, it is confirmed that even when plural kinds of elements are added within the determined amount at the same time, the same effect is obtainable.

A noise filter as shown in FIG. 4 is constituted by using the elements 7 on which electrodes are provided by conductive material such as Ag and a coil 8, and noise input A shown in FIG. 5 is impressed, and thereby noise output B is obtained.

As is obvious from this, noise is sufficiently removed, and that number of components is decreased by combining the simple body element and a coil, and a 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 consisting essentially of:

90.800-99.996 mol % of SrTiO.sub.3,

0.001-0.200 mol % of Nb.sub.2 O.sub.5,

0.001-5.000 mol % of Ta.sub.2 O.sub.5,

0.001-2.000 mol % of MnO.sub.2, and

0.001-2.000 mol % of an oxide of at least one of element selected from the group consisting of Ga, Pt, Tl, Si, Ti, Cs, Au, S, Be, Al, Ca, Cd, In, Ba, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn and Sb.