Abstract:
Nonohmic ZnO ceramics including the following additives have the voltage nonlinear exponent α of 30 or more, the dielectric constant ε of about 1000 or less, the loss factor (tan δ) of less than 10%, and small variations caused in the breakdown voltage V i  by load and large current pulses. The additives listed by molecular formulae are given in % by mol. The glass components are given for Nos. 1 through 4 in % by weight, symbols of elements being representative of borosilicate lead and/or zinc glass. 
     
       ______________________________________ 
     
     No.  Bi 2  O 3         CoO     MnO   Sb 2  O 3                             Glass Component______________________________________1.   0.1-10  0.05-10 0.25-4                      0.05-6                            0.1-10                                  (Pb-Zn)2.   0.1-6   0.05-10 0.25-10                      0.1-10                            0.1-10                                  (Zn)3.   0.1-6   0.05-10 0.23-4                      0.05-6                             0.1-3                                  (Pb)4.   0.1-6   0.05-10 0.2-10                       0.1-6                            0.1-10                                  (Zn and others)______________________________________ 
     As a fifth embodiment, the oxides corresponding or equivalent to a lead-borosilicate glass (PbO, B 2  O 3  and SiO 2 ) may be included in certain amounts with varying amounts of zinc oxide as a major component along with Bi 2  O 3 , CoO, MnO and Sb 2  O 3 .

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to materials of nonohmic resistors, namely, resistors having nonlinear voltage-current characteristics and, more particularly, to materials of nonohmic resistors for use in electric communication apparatus. 
     Nonohmic resistors (hereafter called varistors) have widely been used in surge-absorbing devices, voltage-stabilizing devices, lightning arrestors, and others. In general, a varistor is evaluated by a voltage nonlinear exponent α and a breakdown voltage V i  used in an equation: 
     
         I/i = (V/V.sub.i).sup.α, 
    
     where V i , named the breakdown voltage hereinabove, represents a voltage applied across the varistor to cause a predetermined current i to flow therethrough and I generally represents a current flowing through the varistor when a voltage V is applied thereacross. 
     Sophisticated varistors are silicon varistors, silicon-carbide varistors, selenium rectifiers, cuprous oxide rectifiers, and the like and have various defects such that they have small voltage nonlinear exponents α, that their characteristics are hardly optionally adjustable or controllable, and/or that they are bulky. It has recently been proposed by Michio MATSUOKA in &#34;Japanese Journal of Applied Physics,&#34; Vol. 10, No. 6 (June 1971), pages 736-746, to provide a varistor as a sintered body or mass of zinc oxide ceramics with five additives of bismuth(III) oxide, cobalt(II) oxide, manganese(II) oxide, chromium(III) oxide, and antimony(III) oxide and to thereby remove the above-mentioned defects and widen the field of application of the varistors. The proposed varistor, however, is still unsatisfactory for use in those circuits of recent highly developed electric communication apparatus in which a varistor is mostly used with a load imposed thereon as a surge-absorbing element for absorbing a large current pulse inevitably appearing in the circuit upon on-off of a switch for the circuit and under like circumstances. Furthermore, the proposed varistor is defective in that continued application thereto of a certain electric power results in a decrease in the breakdown voltage V i  and a consequent increase in the leakage current. The proposed varistor likewise when supplied repeatedly with large current pulses does not tend to retain its excellent nonohmic characteristics. 
     Except for specific electric circuits, the voltage nonlinear exponent α of a varistor should be about 30 or more. The breakdown voltage V i  should be adjustable to a nominal voltage preselected for the varistor in consideration of the usage thereof. Dielectric properties are also important when a varistor is used in communication apparatus. The varistor shows a small impedance for that frequency of a signal used in communication apparatus which is rendered more and more higher with the progress of communication techniques. It is therefore desirable that a varistor has a smaller capacitance or dielectric constant ε. It is also desired that a varistor has a smaller dielectric loss (tanδ). The conventional varistor comprising zinc oxide as its principal constituent has had as large as dielectric constant ε and a dielectric loss (tanδ) as about 1000 or more and 10% or more, respectively, and has been unsatisfactory for use in communication apparatus. 
     Proposals have also been made to render the varistors more resistive against the continued load and the large current pulses. One of the proposals is to make the varistor which consists mainly of zinc oxide to include various vitreous materials by one method or another. The improvements thereby achieved, however, have been either for the load or for the large current pulse. This proves that the mechanism of variation caused in the varistor characteristics by the load is different from the mechanism for the large current pulse and that the improvement has consequently been possible for only one of the load and the large current pulse. Furthermore, addition of the vitreous material has raised the breakdown voltage V i  to about 500 volts or more. As a result, varistors for use in communication apparatus have to be rendered very thin in order to provide a compromise between the voltage of the signal used therein and the breakdown voltage so that the varistors do not further withstand a high surge voltage and that the varistors have only weak mechanical strength and unduly large capacitance. 
     SUMMARY OF THE INVENTION 
     It is therefore a general object of the present invention to provide a material for a varistor which is quite satisfactorily usable in a circuit of electric communication apparatus. 
     It is a specific object of this invention to provide a material for a varistor having excellent nonohmic, dielectric, load-resistive, and large current pulse-resistive characteristics. 
     In accordance with one embodiment of this invention, there is provided a nonohmic ceramic material consisting essentially of a main component of zinc oxide, auxiliary components of bismuth(III) oxide of 0.1-10%, cobalt(II) oxide of 0.05-10%, manganese(II) oxide of 0.25-4%, and antimony(III) oxide of 0.05-6%, the percentages being by mol, and as an additional additive borosilicate lead and zinc glass, the material including the additional components of 0.1-10% by weight. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING: 
     FIGS. 1 through 12 show various characteristics of nonohmic ceramic materials according to preferred embodiments of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Nonohmic ceramic materials according to a first embodiment of the present invention consist essentially of a main component of zinc oxide, auxiliary components of 0.1-10% by mol of bismuth(III) oxide, 0.05-10% by mol of cobalt(II) oxide, 0.25-4% by mol of manganese(II) oxide, 0.05-6% by mol of antimony(III) oxide, and additional components of 0.1-10% by weight of borosilicate lead-zinc glass. 
     According to a second embodiment of this invention, the percentages of the bismuth, manganese, and antimony oxides are changed to 0.1-6%, 0.25-10%, and 0.1-10% by mol, respectively, with borosilicate zinc glass substituted for the borosilicate lead-zinc glass. 
     According to a third embodiment of this invention, use is made of the percentages of the bismuth oxide and of the other auxiliary component oxides as in the second and the first embodiments, respectively, with the additional components changed to borosilicate lead glass of 0.1-3% by weight. 
     According to a fourth embodiment of this invention, the percentages of the antimony oxide is changed in the second embodiment to 0.1-6% by mol with at least one of lead(II) oxide, aluminium oxide, cerium oxide, barium oxide, titanium(IV) oxide, tin(IV) oxide, tantalum(V) oxide, phosphorus pentoxide, calcium oxide, diarsenic trioxide, and zirconium(IV) oxide (except the lead oxide only) added to the borosilicate zinc glass. 
     According to a fifth embodiment of this invention, nonohmic ceramic materials consist essentially of a main component of zinc oxide, auxiliary components of 0.10-3.00% by mol of bismuth(III) oxide, 0.10-10.00% by mol of cobalt(II) oxide, 0.10-5.00% by mol of manganese(II) oxide, and 0.10-5.00% by mol of antimony(III) oxide, and additional components of 0.01-0.50% by mol of silicon(IV) oxide, 0.01-1.00% by mol of boron oxide, and 0.01-0.50% by mol of lead(II) oxide. It is obvious that the additional components correspond to or are equivalent to borosilicate lead glass although actual formation of the glass in the ceramics has not yet been confirmed. The ceramic materials contain from 0.03% to about 3% by weight of the additional components, namely, the borosilicate lead glass equivalent. 
     In addition to the properties mentioned in the preamble of the instant specification, it is necessary for a varistor that its electrodes do not exfoliate even when the varistor is subjected to repeated temperature cycles. It has been confirmed that a varistor made of any ceramic material according to the first through fifth embodiments of this invention is strong against temperature cycles. 
     As starting materials for varistors made of ceramic materials according to the first through fourth embodiments, use was made of powdered zinc oxide of a purity equal to 99% or higher, bismuth(III) oxide, cobalt(II) oxide, manganese(II) carbonate, antimony(III) oxide, and borosilicate lead and/or zinc glass frit. The glass frit was of various compositions listed by percentages by weight in Tables 1 and 2 hereunder. According to the fifth embodiment, use was made, in addition to the above-mentioned oxides and carbonate, of powdered silicon(IV) oxide, boron oxide, and lead(II) oxide to provide the additional components corresponding or equivalent to borosilicate lead glass. Typical percentages by mol of the additional compositions are given in Table 3 below, wherein the compositions marked with asterisks are outside of the percentages used in the fifth embodiment. 
     
                       Table 1______________________________________glass frit   SiO.sub.2                 B.sub.2 O.sub.3                          ZnO    PbOAA           10.8     27.2     60.0   2.0AB           2.0      10.0     12.5   75.5AC           9.5      27.0     63.4   0.1AD           0.1      55.4     44.4   0.1AE           12.0     23.5     56.0   8.5AF           27.0     8.0      0.1    64.9AG           72.3     20.7     0.1    6.9BA           11.8     28.1     60.1BB           42.1     10.4     47.5BC           22.1     22.8     55.1BD           65.3     9.5      25.2BE           39.2     21.0     39.8CA           26       8               66CB           35       13              52CC           75       15              10CD           50       10              40CE           50       25              25CF           34       28              38______________________________________ 
    
     
                       Table 2______________________________________ glass frit     DA      DB      DC    DD    DE    DFSiO.sub.2 11.8    2.1     12.0  9.2   10.7  6.2B.sub.2 O.sub.3     28.1    9.4     23.2  27.8  28.5  18.6ZnO       60.1    12.3    52.1  50.4  50.9  24.1PbO               70.1    6.8               43.3Al.sub.2 O.sub.3  0.6           0.4   0.2CeO.sub.2         1.1           3.8   5.1BaO                       2.6               1.8TiO.sub.2         3.9           4.1SnO.sub.2                 1.8               2.2Ta.sub.2 O.sub.5                      0.2   1.1P.sub.2 O.sub.5           1.1   3.6CaO                       0.2As.sub.2 O.sub.3          0.4ZrO.sub.2                       0.7         3.7______________________________________ 
    
     
                       Table 3______________________________________glass equivalent           SiO.sub.2                    B.sub.2 O.sub.3                             PbO*EA             0.00     0.30     0.05EB              0.01     &#34;        &#34;EC              0.05     &#34;        &#34;ED              0.10     &#34;        &#34;EE              0.50     &#34;        &#34;*EF             1.00     &#34;        &#34;*EG             0.05     0.00     &#34;EH              &#34;        0.01     &#34;EI              &#34;        0.05     &#34;EJ              &#34;        0.10     &#34;EK              &#34;        1.00     &#34;*EL             &#34;        2.00     &#34;*EM             &#34;        0.30     0.00EN              &#34;        &#34;        0.01EO              &#34;        &#34;        0.10EP              &#34;        &#34;        0.50*EQ             &#34;        &#34;        1.00______________________________________ 
    
     Throughout the first through fourth embodiments, the powdered oxides and carbonate were weighed out, mixed together with addition thereto of pure water in a ball mill for twenty-four hours, filtered, dried, calcined at 650° C.-850° C., and pressure-shaped into disks, 16 mm in diameter, with addition thereto of a small amount of a binder (5% aqueous solution of polyvinyl alcohol). For the fifth embodiment, weighed out powder of the oxides and carbonate of the auxiliary and additional components were mixed for two hours by the use of a grinder before the calcination. The disks were sintered at 1100° C.-1300° C. for one hour into ceramics, which were ground to a thickness of 1 mm. A pair of silver electrodes, 8 mm in diameter, were fired to each ground ceramic disk to provide a sample. 
     The voltage nonlinear exponent α and the breakdown voltage V i  were calculated from the results of measurement of the voltage-current characteristics carried out by the use of d.c. power or pulses produced by a curve tracer. The capacitance and the loss factor (tanδ) were measured by the use of a capacitance bridge at 1 kHz. The load characteristics were evaluated by a change in the breakdown voltage V i  for a current of 10 microamperes at room temperature before and after a power of 1.5 W/cm 2  was imposed for three hours on each sample kept at 80° C. in a thermostat. The large current pulse characteristics were similarly evaluated by a variation in the breakdown voltage V 10 μA before and after current pulses of 200 amperes (the current wave form being 10 × 200 microseconds) were caused to flow through each sample twenty times at an interval of 30 seconds. For use in communication apparatus, the load and the large current pulse characteristics should be about 20% and about 5%, respectively, or less. The temperature cycle test was carried out for a change in the capacitance before and after each sample was subjected fifteen times to a temperature cycle of -65° C., 25° C., 125° C., and 25° C. 
     Typical results are listed in Table 4 wherein V i , the breakdown voltage, is given in volts for the above-mentioned samples when the current density is 1 mA/cm 2 , tanδ, the loss factor, is given in percentage, and &#34;L,&#34; &#34;P,&#34; and &#34;T&#34; represent in percentages the load and the large current pulse characteristics and the results of temperature cycle tests, all mentioned above. Samples numbered with asterisks are not made of nonohmic ceramic materials according to the first through fifth embodiments. The temperature cycle tests were not carried out for samples made of nonohmic ceramic materials including the borosilicate lead glass equivalents listed in Table 3. For reference, similar data are shown in Table 4 for like samples made of zinc oxide ceramics including no borosilicate glass equivalent. 
     
                                           Table 4__________________________________________________________________________No.   ZnO Bi.sub.2 O      CoO         MnO            Sb.sub.2 O.sub.3                glass                   α                     V.sub.i                        ε                            tanδ                               L    P    T__________________________________________________________________________glass: AA*1 95.0  1.0 1.0         1.0            2.0 0.05                   45                     260                        800 10.5                               -79  -10  -1302  &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   48                     245                        770 7.5                               -15  -4   03  &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   61                     267                        637 3.4                               -7   +1   &#34;4  &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   53                     260                        600 2.8                               -10  -2   &#34;5  &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   46                     252                        553 3.4                               -13  -3   &#34;6  &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   42                     250                        503 4.6                               -18  -5   &#34;*7 &#34;   &#34;   &#34;  &#34;  &#34;   20.0                   43                     250                        500 7.5                               -25  -10  -20*8 96.0  0.0 &#34;  &#34;  &#34;   1.0                    7                     163                        698 30.5                               -99  -30  09  95.9  0.1 &#34;  &#34;  &#34;   &#34;  40                     283                        585 8.5                               -20  -4   &#34;10 95.6  0.4 &#34;  &#34;  &#34;   &#34;  63                     343                        467 1.6                               -15  0    &#34;11 92.0  4.0 &#34;  &#34;  &#34;   &#34;  39                     161                        912 8.5                               -12  -2   &#34;12 86.0  10.0      &#34;  &#34;  &#34;   &#34;  30                     100                        960 9.5                               -19  -4   &#34;*13   76.0  20.0      &#34;  &#34;  &#34;   &#34;  15                     100                        970 20.0                               -50  -10  -15*14   96.0  1.0 0.0         &#34;  &#34;   &#34;  60                     360                        430 5.5                               -75  -25  015  95.95  &#34;    0.05         &#34;  &#34;   &#34;  82                     350                        499 3.8                               -18  -5   &#34;16 95.6  &#34;   0.4         &#34;  &#34;   &#34;  72                     291                        556 3.5                               -15  -3   &#34;17 92.0  &#34;   4.0         &#34;  &#34;   &#34;  65                     256                        598 2.7                               -13  -3   &#34;18 86.0  &#34;   10.0         &#34;  &#34;   &#34;  48                     304                        532 5.2                               -19  -5   &#34;*19   76.0  &#34;   20.0         &#34;  &#34;   &#34;  40                     300                        530 5.2                               -60  -20  -20*20   96.0  &#34;   1.0         0.0            &#34;   &#34;  40                     194                        1020                            2.3                               -99  -35  -1121  95.75  &#34;   &#34;   0.25            &#34;   &#34;  46                     205                        760 2.4                               -19  -5   022 95.6  &#34;   &#34;  0.4            &#34;   &#34;  51                     224                        634 2.6                               -15  -4   &#34;23 92.0  &#34;   &#34;  4.0            &#34;   &#34;  66                     295                        528 8.5                               -13  -3   &#34;*24   86.0  &#34;   &#34;  10.0            &#34;   &#34;  60                     300                        400 8.5                               -30  -15  -20*25   97.0  &#34;   &#34;  1.0            0.0 &#34;  51                     155                        2398                            5.9                               -99  -32  026  96.75  &#34;   &#34;  &#34;   0.05                &#34;  53                     150                        960 5.5                               -20  -4   &#34;27 96.6  &#34;   &#34;  &#34;  0.4 &#34;  53                     150                        730 5.3                               -15  +1   &#34;28 93.0  &#34;   &#34;  &#34;  4.0 &#34;  47                     329                        249 2.6                               -12  -2   &#34;29 91.0  &#34;   &#34;  &#34;  6.0 &#34;  40                     350                        198 8.5                               -18  -5   &#34;*30   87.0  &#34;   &#34;  &#34;  10.0                &#34;  35                     360                        200 9.0                               -30  -15  &#34;glass: AB*31   95.0  1.0 1.0         1.0            2.0 0.05                   48                     220                        800 9.5                               -30  -6   -1832 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   48                     212                        866 8.6                               -15  -4   033 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   48                     210                        794 6.6                               -15  +1   &#34;34 &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   40                     180                        1100                            9.5                               -45  +1   &#34;glass: AC*35   95.0  1.0 1.0         1.0            2.0 0.05                   50                     234                        850 10.9                               -40  -10  -3536 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   53                     234                        839 7.4                               -20  -5   037 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   61                     256                        538 3.0                               -8   +4   &#34;38 &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   62                     277                        396 2.7                               -12  0    &#34;39 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   61                     280                        357 4.8                               -15  -3   &#34;40 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   51                     282                        273 6.7                               -19  -5   &#34;*41   &#34;   &#34;   &#34;  &#34;  &#34;   20.0                   50                     280                        270 7.0                               -35  -5   -20glass: AD*42   93.0  1.0 1.0         1.0            2.0 0.05                   42                     275                        900 7.9                               -30  -3    -4043 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   44                     280                        880 6.8                               -18  -4   044 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   40                     285                        850 8.5                               -50  -10  &#34;glass: AE*45   95.0  1.0 1.0         1.0            2.0 0.05                   45                     250                        890 15.0                               -5   -7   -1546 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   47                     249                        870 7.8                               -4   -4   047 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   46                     300                        814 3.4                               -10  -4   &#34;48 &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   42                     350                        650 2.7                               -15  -5   &#34;49 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   40                     360                        600 1.0                               -25  -6   &#34;glass: AF*50   95.0  1.0 1.0         1.0            2.0 0.05                   45                     250                        850 9.0                               -40  - 4  -1351 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   47                     249                        830 6.7                               -13  -4   052 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   46                     300                        692 3.1                               -15  -2   &#34;53 &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   42                     350                        520 2.8                               -13  -3   &#34;54 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   40                     400                        500 5.0                               -50  -6   -15glass: AG*55   95.0  1.0 1.0         1.0            2.0 0.05                   45                     270                        815 11.0                               -45  -20  -2056 &#34;   &#34;   &#34;  &#34;  &#34;   0.1                   51                     244                        783 5.0                               -19  -5   057 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   40                     310                        522 3.9                               -12  -5   &#34;58 &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   37                     380                        440 2.2                               -14  -4   &#34;59 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   32                     410                        430 2.7                               -18  -2   &#34;60 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   35                     450                        420 3.5                               -36  -15  &#34;glass: BA61 95.0  1.0 1.0         1.0            2.0 0.1                   53                     236                        820 7.3                               -18  -4   062 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   64                     258                        523 3.1                               -5   +4   &#34;63 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   62                     277                        386 4.8                               -14  -2   &#34;64 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   57                     280                        281 6.7                               -18  -5   &#34;*65   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   21                     335                        218 9.8                               -25  -13*66   96.0  0.0 &#34;  &#34;  &#34;   1.0                    5                      79                        8320                            11.7                               -92  -3967 95.9  0.1 &#34;  &#34;  &#34;   &#34;  34                     204                        469 2.4                               -16  -4   068 95.6  0.4 &#34;  &#34;  &#34;   &#34;  57                     318                        318 2.0                               -7   +2   &#34;69 90.0  6.0 &#34;  &#34;  &#34;   &#34;  58                     196                        589 7.6                               -13  -3   &#34;*70   86.0  10.0      &#34;  &#34;  &#34;   &#34;   4                      72                        2160                            28.8                               -26  -771 96.0  1.0  0.05         &#34;  &#34;   &#34;  71                     415                        312 2.6                               -19  -5   072 95.6  &#34;   0.4         &#34;  &#34;   &#34;  62                     304                        418 2.7                               -7   -5   &#34;73 92.0  &#34;   4.0         &#34;  &#34;   &#34;  52                     234                        520 2.3                               -11  +1   &#34;74 86.0  &#34;   10.0         &#34;  &#34;   &#34;  41                     276                        578 4.6                               -17  -2   &#34;*75   66.0  &#34;   30.0         &#34;  &#34;   &#34;  35                     328                        677 7.2                               -24  -4*76   96.0  &#34;   1.0         0.0            &#34;   &#34;  45                     154                        1080                            2.4                               -8   -677  95.75  &#34;   &#34;   0.25            &#34;   &#34;  47                     198                        530 2.1                               -4   -3   078 92.0  &#34;   &#34;  4.0            &#34;   &#34;  57                     271                        482 6.5                               -7   0    &#34;79 86.0  &#34;   &#34;  10.0            &#34;   &#34;  43                     309                        512 7.8                               -14  -2   &#34;*80   66.0  &#34;   &#34;  30.0            &#34;   &#34;  32                     344                        883 18.9                               -24  -4*81   97.0  &#34;   &#34;  1.0            0.0 &#34;  51                     146                        2430                            5.2                               -26  -482 96.9  &#34;   &#34;  &#34;  0.1 &#34;  55                     147                        840 4.7                               -19  -2   083 93.0  &#34;   &#34;  &#34;  4.0 &#34;  52                     288                        470 3.1                               -6   0    &#34;84 87.0  &#34;   &#34;  &#34;  10.0                &#34;  44                     343                        258 2.4                               -4   -2   &#34;*85   67.0  &#34;   &#34;  &#34;  30.0                &#34;  18                     983                         80 20.6                               -15  -5glass: BB86 95.0  1.0 1.0         1.0            2.0 0.1                   48                     246                        770 6.8                               - 11 -5   087 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   53                     268                        652 3.5                               -7   +2   &#34;88 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   47                     254                        633 3.2                               -12  0    &#34;89 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   41                     273                        576 4.9                               -15  -3   &#34;*90   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   27                     432                        372 8.8                               -22  -9glass: BC91 95.0  1.0 1.0         1.0            2.0 0.1                   49                     248                        788 7.1                               -15  -2   092 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   60                     261                        486 3.0                               -6   +2   &#34;93 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   58                     267                        431 3.1                               -7   0    &#34;94 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   46                     258                        440 6.2                               -11  -4   &#34;*95   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   41                     249                        451 10.4                               -19  -11glass: BD96 95.0  1.0 1.0         1.0            2.0 0.1                   44                     224                        743 5.9                               -14  -2   097 &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   47                     218                        421 2.7                               -9   0    &#34;98 &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   41                     198                        443 3.4                               -11  -3   &#34;99 &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   38                     187                        451 4.7                               -15  -5   &#34;*100   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   32                     234                        388 9.6                               -23  -9glass: BE101   95.0  1.0 1.0         1.0            2.0 0.1                   51                     268                        610 6.1                               -13  -5   0102   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   63                     252                        453 3.3                               -7   -3   &#34;103   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   62                     248                        399 3.6                               -8   -2   &#34;104   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   54                     255                        432 4.9                               -11  -4   &#34;*105   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   42                     261                        484 7.5                               -18  -21glass: CA106   95.0  1.0 1.0         1.0            2.0 0.1                   57                     267                        610 4.6                               -14  -3   0107   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   55                     320                        262 2.6                               -16  0    &#34;108   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   41                     363                        198 2.7                               -19  -4   &#34;*109   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   36                     415                        164 2.9                               -38  -16*110   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   23                     432                        123 4.7                               -75  -48*111   96.0  0.0 &#34;  &#34;  &#34;   0.1                    3                      56                        3892                            30.6                               -98  -34112   95.9  0.1 &#34;  &#34;  &#34;   &#34;  31                     240                        573 7.8                               -19  -4   0113   95.6  0.4 &#34;  &#34;  &#34;   &#34;  49                     386                        343 2.5                               -17  -2   &#34;114   92.0  4.0 &#34;  &#34;  &#34;   &#34;  46                     284                        582 6.7                               -19  -3   &#34;115   90.0  6.0 &#34;  &#34;  &#34;   &#34;  43                     252                        566 7.4                               -20  -5   &#34;*116   86.0  10.0      &#34;  &#34;  &#34;   &#34;  41                     234                        632 11.5                               -48  -20*117   96.0  1.0 0.0         &#34;  &#34;   &#34;  38                     343                        398 4.6                               -84  -26118    95.95  &#34;    0.05         &#34;  &#34;   &#34;  39                     323                        432 3.9                               -20  -5   0119   95.6  &#34;   0.4         &#34;  &#34;   &#34;  37                     315                        475 3.4                               -16  -3   &#34;120   92.0  &#34;   4.0         &#34;  &#34;   &#34;  44                     289                        534 2.2                               -15  -4   &#34;121   86.0  &#34;   10.0         &#34;  &#34;   &#34;  36                     287                        538 6.6                               -19  -5   &#34;*122   96.0  &#34;   1.0         0.0            &#34;   &#34;   4                     124                        1493                            2.8                               -99  -35123    95.75  &#34;   &#34;   0.25            &#34;   &#34;  31                     205                        837 2.4                               -20  -4   0124   95.6  &#34;   &#34;  0.4            &#34;   &#34;  34                     405                        215 1.9                               -15  -4   &#34;125   92.0  &#34;   &#34;  4.0            &#34;   &#34;  33                     344                        373 4.1                               -17  -5   &#34;*126   86.0  &#34;   &#34;  10.0            &#34;   &#34;  18                     291                        540 32.2                               -49  -12*127   97.0  &#34;   &#34;  1.0            0.0 &#34;  18                     163                        1184                            3.5                               -99  -31128    96.95  &#34;   &#34;  &#34;   0.05                &#34;  30                     274                        608 3.2                               -20  -4   0129   96.6  &#34;   &#34;  &#34;  0.4 &#34;  34                     332                        429 2.4                               -17  -3   &#34;130   93.0  &#34;   &#34;  &#34;  4.0 &#34;  33                     304                        498 5.6                               -14  -2   &#34;131   91.0  &#34;   &#34;  &#34;  6.0 &#34;  31                     300                        529 7.3                               -19  - 5  &#34;*132   87.0  &#34;   &#34;  &#34;  10.0                &#34;   4                     145                        1321                            26.4                               -66  -21glass: CB133   95.0  1.0 1.0         1.0            2.0 0.1                   48                     254                        743 6.7                               -15  -4   0134   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   51                     325                        705 3.2                               -17  +1   &#34;135   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   38                     375                        517 2.8                               -20  -5   &#34;*136   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   27                     443                        508 2.6                               -32  -18*137   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   21                     472                        342 9.7                               -76  -43glass: CC138   95.0  1.0 1.0         1.0            2.0 0.1                   47                     252                        774 5.2                               -17  -1   0139   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   40                     330                        472 4.1                               -18  +2   &#34;140   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   33                     420                        437 2.9                               -20  -3   &#34;glass: CD141   95.0  1.0 1.0         1.0            2.0 0.1                   48                     257                        730 6.3                               -16  -2   0142   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   47                     298                        395 2.9                               -17  -1   &#34;143   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   33                     368                        304 2.7                               -20  -4   &#34;*144   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   24                     439                        273 3.4                               -43  -14glass: CE145   95.0  1.0 1.0         1.0            2.0 0.1                   48                     263                        701 5.8                               -17  -1   0146   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   45                     346                        332 3.9                               -19  -3   &#34;147   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   39                     412                        243 2.5                               -20  -5   &#34;*148   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   29                     464                        198 3.2                               -58  -21glass: CF149   95.0  1.0 1.0         1.0            2.0 0.1                   51                     257                        723 6.4                               -18  0    0150   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   44                     284                        349 3.3                               -18  +1   &#34;151   &#34;   &#34;   &#34;  &#34;  &#34;   3.0                   36                     323                        256 2.6                               -20  -5   &#34;*152   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   31                     365                        204 3.1                               -57  -14glass: DA153   95.0  1.0 1.0         1.0            2.0 0.1                   53                     236                        820 7.3                               -18  -4   0154   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   64                     258                        523 3.1                               -5   +4   &#34;155   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   62                     277                        386 4.8                               -14  -2   &#34;156   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   57                     280                        281 6.7                               -18  -5   &#34;*157   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   21                     335                        218 9.8                               -25  -13glass: DB158   95.0  1.0 1.0         1.0            2.0 0.1                   51                     198                        793 6.5                               -16  -3   0159   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   62                     196                        703 2.8                               -6   +2   &#34;160   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   56                     198                        722 2.2                               -9   -1   &#34;161   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   43                     197                        800 4.1                               -16  -2   &#34;*162   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   37                     196                        845 4.9                               -21  -7*163   96.0  0.0 &#34;  &#34;  &#34;   1.0                    6                      85                        984 46.5                               -96  -28164   95.9  0.1 &#34;  &#34;  &#34;   &#34;  45                     176                        866 8.6                               -18  -5   0165   95.6  0.4 &#34;  &#34;  &#34;   &#34;  58                     198                        721 4.1                               -7   +3   &#34;166   90.0  6.0 &#34;  &#34;  &#34;   &#34;  42                     165                        878 6.9                               -14  -1   &#34;*167   86.0  10.0      &#34;  &#34;  &#34;   &#34;  36                     142                        904 9.1                               -28  -6*168   96.0  1.0 0.0         &#34;  &#34;   &#34;  76                     244                        752 26.2                               -88  -5169    95.95  &#34;    0.05         &#34;  &#34;   &#34;  68                     196                        737 7.6                               -19  -3   0170   95.6  &#34;   0.4         &#34;  &#34;   &#34;  62                     192                        728 5.3                               -4   -2   &#34;171   92.0  &#34;   4.0         &#34;  &#34;   &#34;  54                     189                        745 6.6                               -2   -2   &#34;172   86.0  &#34;   10.0         &#34;  &#34;   &#34;  41                     198                        796 9.4                               -11  -4   &#34;*173   96.0  &#34;   1.0         0.0            &#34;   &#34;  38                     181                        894 10.2                               -17  -6174    95.95  &#34;   &#34;   0.25            &#34;   &#34;  45                     183                        875 6.3                               -8   -3   0175   95.6  &#34;   &#34;  0.4            &#34;   &#34;  53                     186                        798 4.8                               -4   -2   &#34;176   92.0  &#34;   &#34;  4.0            &#34;   &#34;  62                     199                        730 3.6                               -2   +1   &#34;177   86.0  &#34;   &#34;  10.0            &#34;   &#34;  41                     197                        738 7.1                               -14  -4   &#34;178   96.9  &#34;   &#34;  1.0            0.1 &#34;  46                     174                        698 5.4                               -19  -3   &#34;179   96.6  &#34;   &#34;  &#34;  0.4 &#34;  53                     187                        743 5.2                               -8   -2   &#34;180   96.0  &#34;   &#34;  &#34;  1.0 &#34;  61                     196                        706 4.8                               -5   +1   &#34;181   91.0  &#34;   &#34;  &#34;  6.0 &#34;  43                     199                        702 5.4                               -9   -3   &#34;*182   87.0  &#34;   &#34;  &#34;  10.0                &#34;  10                     243                        565 7.9                               -12  -6glass: DC183   95.0  1.0 1.0         1.0            2.0 0.1                   44                     199                        689 7.8                               -4   -4    0184   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   48                     192                        714 3.7                               -6   -3   &#34;185   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   45                     189                        746 2.7                               -8   -4   &#34;186   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   42                     198                        702 4.1                               -15  -5   &#34;*187   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   38                     220                        670 8.8                               -23  -7glass: DD188   95.0  1.0 1.0         1.0            2.0 0.1                   47                     198                        700 6.5                               -10  -3   0189   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   46                     197                        704 4.2                               -5   +2   &#34;glass: DE190   95.0  1.0 1.0         1.0            2.0 0.1                   50                     196                        756 8.5                               -7   -3   0191   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   51                     199                        774 4.3                               -4   +1   &#34;192   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   47                     198                        721 3.8                               -8   -2glass: DF193   95.0  1.0 1.0         1.0            2.0 0.1                   48                     198                        764 7.4                               -14  -4   0194   &#34;   &#34;   &#34;  &#34;  &#34;   1.0                   54                     199                        748 4.5                               -7   +1   &#34;195   &#34;   &#34;   &#34;  &#34;  &#34;   5.0                   51                     197                        776 3.1                               -3   -2   &#34;196   &#34;   &#34;   &#34;  &#34;  &#34;   10.0                   47                     192                        802 5.2                               -4   -4   &#34;*197   &#34;   &#34;   &#34;  &#34;  &#34;   30.0                   42                     186                        854 6.3                               -8   -8No.   ZnO    Bi.sub.2 O.sub.3        CoO           MnO              Sb.sub.2 O.sub.3                  [glass]                      α                        V.sub.i                           ε                               tanδ                                  L   P__________________________________________________________________________glass equivalents: E series*198  94.63    1.00        1.00           1.00              2.00                  EA  45                        221                           715 8.0                                  -25.2                                      -5.5199   94.64    &#34;   &#34;  &#34;  &#34;   EB  50                        225                           710 6.0                                  -15.1                                      -3.5*200  95.55    0.05        &#34;  &#34;  &#34;   EC   5                        112                           500 2.5                                  --  --201   95.50    0.10        &#34;  &#34;  &#34;   &#34;   48                        140                           450 2.3                                  -12.2                                      -4.5202   94.60    1.00        &#34;  &#34;  &#34;   &#34;   58                        227                           700 2.0                                  -16.1                                      -3.2203   92.60    3.00        &#34;  &#34;  &#34;   &#34;   55                        175                           710 1.8                                  -18.3                                      -4.6*204  90.60    5.00        &#34;  &#34;  &#34;   &#34;   45                        160                           715 8.5                                  -35.4                                      -15.3*205  95.60    1.00        0.00           &#34;  &#34;   &#34;   46                        282                           720 6.5                                  -25.8                                      -6.2206   95.50    &#34;   0.10           &#34;  &#34;   &#34;   52                        264                           710 2.0                                  -15.2                                      -5.0207   85.60    &#34;   10.00           &#34;  &#34;   &#34;   55                        234                           705 2.1                                  -16.3                                      -4.0*208  75.00    &#34;   20.00           &#34;  &#34;   &#34;   50                        372                           700 2.4                                  -14.7                                      -18.5*209  95.60    &#34;   1.00           0.00              &#34;   &#34;   38                        200                           710 2.3                                  -25.6                                      -15.4210   95.50    &#34;   &#34;  0.10              &#34;   &#34;   50                        189                           710 2.4                                  -13.5                                      -4.5211   92.60    &#34;   &#34;  3.00              &#34;   &#34;   60                        245                           700 2.5                                  -14.5                                      -3.5212   90.60    &#34;   &#34;  5.00              &#34;   &#34;   62                        250                           710 4.8                                  -15.5                                      -4.5*213  85.60    &#34;   &#34;  10.00              &#34;   &#34;   58                        264                           715 8.8                                  -31.2                                      -10.3*214  96.60    &#34;   &#34;  1.00              0.00                  &#34;   43                        178                           2500                               3.5                                  -48.9                                      -15.4215   96.50    &#34;   &#34;  &#34;  0.10                  &#34;   55                        175                           785 3.4                                  -13.4                                      -4.5216   91.60    &#34;   &#34;  &#34;  5.00                  &#34;   58                        275                           701 3.0                                  -17.5                                      -3.3*217  85.60    &#34;   &#34;  &#34;  10.00                  &#34;   15                        1200                           200 10.5                                  --  -8.0218   94.55    &#34;   &#34;  &#34;  2.00                  ED  51                        227                           700 4.0                                  -16.0                                      -3.6219   94.15    &#34;   &#34;  &#34;  &#34;   EE  52                        284                           682 1.0                                  -18.1                                      -4.2*220  93.65    &#34;   &#34;  &#34;  &#34;   EF  45                        300                           505 2.5                                  -25.3                                      -4.4*221  94.90    &#34;   &#34;  &#34;  &#34;   EG  39                        225                           710 6.5                                  -35.5                                      -10.5222   94.89    &#34;   &#34;  &#34;  &#34;   EH  50                        226                           650 5.2                                  -18.0                                      -3.5223   94.85    &#34;   &#34;  &#34;  &#34;   EI  55                        224                           603 1.0                                  -19.0                                      -3.4224   94.80    &#34;   &#34;  &#34;  &#34;   EJ  54                        226                           610 0.5                                  -18.2                                      -3.6225   93.90    &#34;   &#34;  &#34;  &#34;   EK  53                        220                           612 1.5                                  -16.1                                      -4.5*226  92.90    &#34;   &#34;  &#34;  &#34;   EL  33                        205                           751 2.0                                  -14.0                                      -9.8*227  94.65    &#34;   &#34;  &#34;  &#34;   EM  45                        225                           753 3.5                                  -12.0                                      -10.5228   94.64    &#34;   &#34;  &#34;  &#34;   EN  56                        219                           724 2.4                                  -16.0                                      -3.5229   94.55    &#34;   &#34;  &#34;  &#34;   EO  57                        218                           702 1.0                                  -12.2                                      -3.7230   94.15    &#34;   &#34;  &#34;  &#34;   EP  50                        180                           701 1.0                                  -15.3                                      -3.9*231  93.65    &#34;   &#34;  &#34;  &#34;   EQ  42                        160                           684 2.5                                  -40.1                                      -5.5No    ZnO Bi.sub.2 O.sub.3         CoO            MnO               Sb.sub.2 O.sub.3                   α                     V.sub.i                        ε                            tanδ                               L   P__________________________________________________________________________without glass or glass equivalent232   95.0     1.0 1.0            1.0               2.0 42                     270                        880 12.0                               -98 -28233   &#34;   &#34;   &#34;  &#34;  &#34;   45                     220                        712 8.5                               -85.0                                   -20.5234   96.0     0.0 1.0            1.0               2.0  3                      56                        3950                            35.6                               -89.5                                   -38.5235    95.95      0.05         &#34;  &#34;  &#34;   20                     110                        510 30.1                               --  --236   95.9     0.1 &#34;  &#34;  &#34;   42                     202                        650 10.1                               -80.3                                   -30.2237   95.6     0.4 &#34;  &#34;  &#34;   40                     195                        660 12.1                               -79.5                                   -33.4238   95.5     0.5 &#34;  &#34;  &#34;   43                     214                        703 10.2                               -90.4                                   -34.5239   93.0     3.0 &#34;  &#34;  &#34;   46                     200                        724 8.0                               -95.0                                   -25.4240   92.0     4.0 &#34;  &#34;  &#34;   43                     205                        730 8.1                               -91.2                                   -28.6241   91.0     5.0 &#34;  &#34;  &#34;   40                     210                        732 8.2                               -84.0                                   -30.5242   90.0     6.0 &#34;  &#34;  &#34;   38                     198                        725 8.9                               -88.5                                   -32.6243   96.0     1.0 0.0            &#34;  &#34;   35                     345                        506 8.9                               -88.9                                   -33.5244    95.95     &#34;    0.05            &#34;  &#34;   45                     405                        748 8.5                               -76.5                                   -20.6245   95.9     &#34;   0.1            &#34;  &#34;   40                     350                        734 8.4                               -84.6                                   -30.5246   95.6     &#34;   0.4            &#34;  &#34;   33                     270                        705 7.5                               -93.5                                   -32.4247   95.5     &#34;   0.5            &#34;  &#34;   30                     250                        722 7.8                               -95.4                                   -32.5248   92.0     &#34;   4.0            &#34;  &#34;   32                     265                        718 8.0                               -76.5                                   -45.6249   91.0     &#34;   5.0            &#34;  &#34;   35                     234                        695 7.2                               -90.4                                   -20.2250   86.0     &#34;   10.0            &#34;  &#34;   42                     243                        680 7.6                               -93.2                                   -35.8251   76.0     &#34;   20.0            &#34;  &#34;   43                     241                        698 7.2                               -76.5                                   -33.3252   66.0     &#34;   30.0            &#34;  &#34;   41                     275                        710 8.0                               -78.5                                   -23.5253   96.0     &#34;   1.0            0.0               &#34;    4                     185                        1005                            1.5                               -89.5                                   -33.8254   95.9     &#34;   &#34;  0.1               &#34;   33                     210                        812 4.6                               -83.0                                   -43.5255    95.75     &#34;   &#34;   0.25               &#34;   35                     195                        715 13.9                               -88.5                                   -32.5256   95.6     &#34;   &#34;  0.4               &#34;   34                     302                        702 15.5                               -87.6                                   -29.8257   93.0     &#34;   &#34;  3.0               &#34;   43                     273                        703 8.8                               -76.0                                   -30.4258   92.0     &#34;   &#34;  4.0               &#34;   33                     300                        650 10.6                               -89.5                                   -33.5259   91.0     &#34;   &#34;  5.0               &#34;   35                     305                        670 10.6                               -90.5                                   -34.1260   86.0     &#34;   &#34;  10.0               &#34;   34                     324                        701 12.4                               -83.5                                   -41.0261   97.0     &#34;   &#34;  1.0               0.0 15                     154                        2009                            18.6                               -78.8                                   -32.1262    96.95     &#34;   &#34;  &#34;   0.05                   31                     143                        2004                            13.6                               -98.0                                   -38.2263   96.9     &#34;   &#34;  &#34;  0.1 33                     215                        730 14.3                               -90.0                                   -36.2264   96.6     &#34;   &#34;  &#34;  0.4 32                     204                        715 18.5                               -79.5                                   -31.5265   96.0     &#34;   &#34;  &#34;  1.0 31                     205                        715 19.0                               -80.5                                   -31.2266   93.0     &#34;   &#34;  &#34;  4.0 30                     211                        713 19.6                               -83.4                                   -30.8267   92.0     &#34;   &#34;  &#34;  5.0 32                     220                        724 17.8                               -80.5                                   -31.7268   91.0     &#34;   &#34;  &#34;  6.0 25                     245                        703 13.4                               -93.6                                   -34.6269   87.0     &#34;   &#34;  &#34;  10.0                    4                     740                        653 10.5                               -88.5                                   -32.8__________________________________________________________________________ 
    
     In the above-given Table 4, samples Nos. 232 and 233 are of the same composition and yet showed different results because of the different ambient temperatures. The result of temperature cycle test for the sample No. 232 was -50%. 
     Referring to FIG. 1, the current-voltage characteristic of sample No. 2 is excellent for a wide range of current. The characteristic is excellent particularly with respect to small leakage current in the smaller current range. 
     FIG. 2 shows the voltage nonlinear exponent α, breakdown voltage V 1mA , dielectric constant ε, and loss factor (tanδ) versus the amount of the borosilicate lead-zinc glass as exemplified by samples Nos. 232 and 1-6. FIG. 3 illustrates the load and the large current pulse characteristics versus similar amount of the borosilicate lead-zinc glass. 
     Turning now to FIG. 4, the current-voltage characteristic of sample No. 62 is also excellent like the sample No. 2. FIGS. 5 and 6 are similar to FIGS. 2 and 3 except that samples are Nos. 232 and 61-64. 
     FIG. 7 shows the excellent current-voltage characteristic of sample No. 106. FIGS. 8 and 9 are similar to FIGS. 2 and 3 except that samples are Nos. 232 and 106-110. 
     FIG. 10 again shows the excellent current-voltage characteristic of sample No. 159. FIGS. 11 and 12 are similar to FIGS. 2 and 3 except that samples are Nos. 158-161. 
     It is obvious from Table 4 that the excellent characteristics are obtained by simultaneous addition to the main component of the above-mentioned auxiliary and additional components. Furthermore, it has been confirmed that the additional components, namely, the borosilicate glass and/or its equivalent, may be added to the calcined main and auxiliary components throughout the first through fifth embodiments and that use may be made as the starting materials of carbonates and/or oxalates which become oxides when sintered. The fifth embodiment proves that substitution for the borosilicate lead and/or zinc glass of the additional components corresponding to the glass gives the excellent results. The ranges of the components of the first through fifth embodiments are determined to give the voltage nonlinear exponent α of 30 or more, the breakdown voltage V i  of 500 volts or less, the dielectric constant ε of about 1000 or less, the loss factor (tanδ) of less than 10%, the above-mentioned load characteristics of about 20% or less, and the above-described large current pulse characteristics of about 5% or less. Close inspection of Table 4  will reveal from samples Nos. 34, 44, 49, 54,  and 60 that the nonohmic ceramics according to the first embodiment should include 0.1-5.0%, 0.1-3.0%, 0.1-1.0%, and about 0.1% by weight of the borosilicate lead-zinc glass when the glass frit contains silicon(IV) oxide of about 70% and zinc and lead(II) oxides of about 7% in sum, when the glass first includes the silicon oxide of about 10-30% and the zinc and lead oxides of about 65% in sum, when the glass frit contains the silicon oxide of only about 2% and the lead oxide of about 75%, and the glass frit contains a still smaller amount of about 0.1% of the silicon oxide and the zinc and lead oxides of about 45% in sum, respectively, the percentages of the silicon, zinc, and lead oxides being by weight.