[1]3 1 6 5 8 , 7 2 5 Ujiited States Patent Offi- (cc Patented Apr. 25, 1972 3,658,725 NONLINEAR RESISTOR AND NONLINEAR RESISTOR COMPOSIITON Takeshi Masuyama, Takatsuld, Mehio Matsuoka, Eira. kata, and Yoshio Eda, Fujishirodai, Japan, msignors to Matsushita Electric Industrial Co.,.Ltd., Kadoma, Osaka, Japan Filed July 24, 1970, Ser. No. 57,976 Int. Cl. HOlb 1106 U.S. Cf. 252-518 12 Claims 10 ABSTRACT OF THE DISCLOSURE A resistor composition having a nonlinear voltage characteristic consisting essentially of zinc oxide and, as an 15 additive, at least one member taken from the group consisting of lead fluoride, barium fluoride or strontium fluoride, and a nonlinear resistor made from said composition. The nonlinear resistor composition and the resistor made therefrom have the electrical properties 20 thereof further improved by the addition of at least one member selected from the group consisting of cobalt fluoride, manganese fluoride, stannous fluoride, nickel fluoride, rhromium fluoride, bismuth oxide, cobalt oxide, and manganese oxide. 25 This invention relates to compositions of resistor ceramics having a nonlinear voltage characteristic, i.e. having non-ohmic resistance, and more particularly to 30 compositions for varistors romprising 2@inc oxide having a non-ohmic resistance due to the bulk thereof. The invention also relates to resistors made from this composition. Various resistors ha@ving a nonlinear voltage character- 35 istic such as silicon carbide varistors, selenium rectifiers and germanium or silicon p-n junction diodes, have been widely used for stabilization of voltage or current of electrical circuits. The electrical characteristics of such a nonlinear resistor are expressed by the relation: 40 c where V is the voltage across the resistor, I is the current flowing through the resistor, C is a constant correspond- 45 ing to the voltage at a given current and exponent n is a numerical value greater than 1. The value of n is calctilated by the following equation: n= 10910(12/Il) 60 10910 (V21VI) (2) where V, and V2 are the voltage at given currents 11 and 12, respectively. The desired value of C depends upon the kind of application to which the resistor is to be put. 55 It is ordinarily desirable that the value of n be as large as possible since this exponent determines the extent to which the resistors depart from ohmic characteristics. in conventional varistors comprising germanium or silicon p-n junction diodes, it is difficult to control the oo C-value over a wide range because the nonlinear voltage property of these varistors is not attributable to the bulk of the resistor material but to the p-n junction between the body of the varistor and an electrode or electrodes. On the other hand, silicon carbide varistors have non- 6,5 linear voltage properties due to the contacts among tliz 2 individual grains of silicon carbide bonded together by a ceramic binding material, and the C-value is controlled by changing the dimension in the direction, in which the current flows through the varistors. Silicon carbide varistors, however, have a relatively low n-value and are prepared by firing in a non-oxidizing atmosphere, especially for the purpose of obtaining a lower Cvalue. An object of the present invention is to provide a resistance composition for a resistor having a nonlinear voltage characteristic, i.e. non-ohmic properties, due to the bulk thereof and having a controllable C-value. Another object of the present invention is to provide a composition for a resistor having a nonlinear voltage characteristic characterized by a high n-value. Another object of the present invention is to provide a resistor made from such a composition. The details of the invention will become apparent upon consideration of the following description taken together with the accompanying drawing in which the single figure is a partly crosssectional view of a resistor having a nonlinear voltage characteristic according to the invention. Before proceeding with a detailed description of the resistance composition and resistors contemplated by the invention, the resistor construction will be described with reference to the aforesaid figure of drawing wherein reference character 10 designates, as a whole, a resistor having a nonlineax voltage characteristic comprising, as its active elernent, a sintered body having a pair of electrodes 2 and 3 applied to opposite surfaces thereof. Said sintered body I is prepared in a manner hereinafter set forth and can be in any form such as circular, square or rectan-ular plate form. Wire leads 5 and 6 are attached conductively to the electrodes 2 and 3, respectively, by a ronnection means 4 such as solder or the like. A resistor having a nonlinear voltage characteristic according to the invention comprises a sintered body of a composition consisting essentially of, as a -major part, 90.0 to 99.95 mole percent of zinc oxide and, as an additive, 0.05 to 10.0 mole percent of at least one member selected from the group consisting of lead fluoride, barium fluoride and strontium fluoride. Such a resistor has non-ohmic resistance due to the bulk itself. Therefore, its C-value can be changed without impairing the nvalue by changing the distance between the opposite surfaces of a body thereof. A shorter distance results in a lower C-value. A higher n-value can be obtained when said additive consists essentially of at least one member selected from the group consisting of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent of barium fluoride and 0.3 to 3.0 mole percent of strontium fluoride in accordance with the invention. The n-value is further elevated when said sintered body further includes 0.05 to 10.0 mole percent of at least one member selected from the group consisting of cobalt fluoride, manganese fluoride, stannous fluoride, nickel fluoride and chromium fluoride. According to the present invention, the stability with respect to ambient temperature and during an electric load life test can be improved when said additive consists essentially of at least one member selected from the group consisting of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent of barium fluoride and 0.3 to 3.0 mole percent of strontium fluoride and 0.1 to 3.0 mole percent of at least one member selected from the group
[2]consisting of cobalt -fluoride, manganese fluoride, stannous fluoride, nickel fluoride and chromium fluoride. The n-value is greatly elevatedwhen said additive consists essentially of 0.05 to 5.0 mole percent of bismuth oxide and at least one member selected from the group consisting of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent of barium fluoride and 0.3 to 3.0 mole percent of strontium fluoride. An extremely high n-value can be obtained when said additive consists essentially of 0.05 to 5.0 mole percent of cobalt oxide and at least one member selected from the group consisting of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent of barium fluoride and 0.3 to 3.0 mole percent of strontium fluoride. Further, according to the present invention, an extremely high n-value can be obtained also when said additive consists essentially of 0.05 to 5.0 mole percent of manganese oxide and at least one member selected from the group consisting of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent,of barious fluoride and 0.3 to 3.0 mole percent Of strontium fluoride. The sintered body I can be prepared by a per se well known ceramic technique. The starting materials of the compositions described in the foregoing description are mixed in a wet mill so as to produce homogeneous mixtures. The mixtures are dried and pressed in a mold into desired shapes at a pressure of from 100 kg./CM.2 to 1000 kg./eM.2. The pressed bodies are sintered in air at a given temperature for I to 3 hours, and then fumace-cooled to room temperature (about 15' to about 30' C.). The sintering temperature is determined by the desired electrical resistivity, nonlinearity and stability and ranges from 1000' to 1450' C. The mixtures can be preliminarily calcined at about 700' C. and pulverized for easy fabrication in the subsequent pressing step. The mixture to be pressed can be admixed with a suitable binder such as wa-ter, polyvinyl alcohol, etc. It is advantageous that the sintered body have the opposite surfaces lapped by abrasive powder such as silicon carbide having a particle size of 300 mesh to 1500 mesh. The sintered bodies are provided, on the opposite surfaces thereof, with electrodes by any available and suitable method such as an electroplating method, a vacuum evaporation method, a metallizing method or a spraying or silver painting method. The nonlinear properties are not affected to any practical extent by the kinds of electrodes used, but are affected by the thickness of the sintered bodies. Particularly, the C-value varies in proportion to the thickness of the sintered bodies, while the n-value is almost independent of the thickness. This means that the nonlinear voltage property is due to the bulk of the body, and not to the electrodes. Lead wires can be attached to the electrodes in a per se conventional manner by using conventional solder having a low melting point. It is convenient to employ a conductive adhesive comprising silver powder and resin in an organic solvent in order to connect the lead wires to the electrodes. Resistors having a nonlinear voltage characteristic according to this invention have a high stability with respect to temperature and in a load life test, which is carried out -at 70' C. at a rating power for 500 hours. The n-value and C-value do not change very much after heating cycles and a load life test. It is advantageous for achievement of a high stability with respect to humidity that the resultant voltage varia@ble resistors be embedded in a humidity-proof resin such as epoxy resin or phenol resin in a per se well known manner. Pr6sently preferred illustrative embodiments of the invention are as follows. EXAMPLE I A mixture of zinc oxide and an additive in amounts as shown in Table I are mixed in a wet mill for 3 hours. The 3)658)725 4 mixture is dried and then calcined at 700@' C. for I hour. The calcined mixture is pulverized by a motor-driven ceramic mortar for 30 minutes and then pressed in a mold into a shape 17.5 mm. in diameter and 2.5 mm. thick at a pressure of 500 kg./CM.2. The pressed body is sintered in air at 1350' C. for I hour, and then furnace-cooled to room temperature (about 15' to about 30' C.). The sintered disc has the opposite surfaces lapped by silicon carbide having a particle size 10 of 600 mesh. The resulting sintered disc is 14 mm. in diameter and 1.5 mm. thick. Silver paint electrodes commercially available are attached to the opposite surfaces of the sintered disc by painting. Then lead wires are attached to the silver electrodes by soldering. The electric charac15 teristics of the resultant resistors are shown in Table 1. It will be readily understood that the zinc oxide sintered body having incorporated therein lead fluoride, barium fluoride, or strontium fluoride in an amount of 0.05 to 10.0 mole percent is useful for a resistor having a iion20 linear voltage characteiistic, and particularly the addition of 0.5 to 2.0 mole percent of lead fluoride, 0.5 to 2.0 mole percent of barium fluoride or 0.3 to 3.0 mole percent of strontium fluoride makes the nonlinear voltage property more excellent. 25 Similar results can be obtained from a zinc oxide sintered body having incorporated therein two or more fluorides selected from the group consisting of lead fluoride, barium fluoride and strontium fluoride. For example, in a zinc oxide body prepared as described above to which 0.5 30 mole percent of lead fluoride and 0.5 mole percent barium fluoride have been added results in 200 volts C-value at 1 ma. and an n-value of 7.2. TABLE I Electri al character@ AdditiN - isties - percent) C (at 1 ma.) n PbFz 0.05 -------- 505 3.7 PbF2 0.1 --------- 450 4.5 40 PbF@ 0.3 --------- 400 B. 0 PbF2 0.5 --------- 380 6.2 PbF2 2 ----------- 410 5.8 PbF2 3 ----------- 460 4.1 PbF2 10 ---------- 650 3.8 BaF2 0.05 -------- 840 4.0 BaF2 0.1 --------- 560 5.2 45 BaF2 0.3 --------- 150 5.4 BaF2 0.6 --------- 80 7.6 BaF2 2 ----------- 180 7. 0 BaF2 3 ---------- 240 5.4 BaF2 10 ---------- 760 3.8 SrF2 0-05 --------- 610 3.3 50 SrF2 0-1 ---------- 330 4.0 SrF2 0.3 ---------- 110 5.0 SrF2 0.5 ---------- 56 5.9 SrF2 2 ------------ 90 6.2 SrF2 3 ------------ 140 5.8 SrF2 10 ----------- 610 3.9 55 EXAMPLE 2 Starting materials composed of 99.5 mole percent of zinc oxide and 0.5 mole percent of an additive as listed in Table 2 are mixed, dried, calcined and pulverized in the 60 same manner as those of Example 1. The pulverized mixture is pressed in a mold into discs 17.5 mm. in diameter and 5 mm. thick at a pressure of 500 kg./CM.2. The pressed bodies are sintered in air at 1350' C. for I hour, and then furnacecooled to room temperature. The 65 sintered discs have the opposite surfaces thereof ground by silicon carbide having a particle size of 600 until the discs have thicknesses as shown in Table 2. The ground discs are provided with electrodes and lead wires on the opposite surfaces in a manner similar to that of Example 1. 70 The electric characteristics of the resultant resistors are shown in Table 2; the Cvalues vary approximately in proportion to the thicknesses of the sintered discs while the ii-value is essentially independent of the thickness. It will be readily realized that the nonlinear voltage properties of 75 the resistors are attributable to the sintered body itself,
[3]TABLE2 Electrical C haracteristics Additive (mole percent) c (at 1 ma.) n 5 PbF2 (0-5) ------------------------- 24.1 1,070 6. 3 3.5 9 25 6.1 3.0 7 50 6.2 2.5 6 50 6.2 2.0 5 32 6.1 1.5 3 80 6.2 1.0 2 60 6.1 10 ]BaF2 (0-5) -------------------------- Ito 223 7. 8 3.5 19 0 7.6 3.0 16 2 7.6 2.5 13 5 7.5 2.0 11 1 7.4 1.5 8 0 7.6 1.0 5 5 7.3 15 SrF2 (0-5) -------------------------- 13.9 153 6. 0 3.5 13 3 6.0 3.0 11 3 5 ' 9 2.5 9 5 6.0 2.0 7 5 5.9 1.5 5 6 1.0 3 8 6- 9 20 5.7 1 Initial. EXAMPLE 3 Zinc oxide containing additives as set forth in Tables 3 , 21 4, 5 and 6 is fabricated into nonlinear voltage resistors by the same process as that of Example 1. The n-values of the resultaing resistors are shown in Tables 3, 4, 5 and 6. It will be readily seen that the combination of lead fluoride, barium fluoride or strontium fluoride with one fluo- 30 ride selected from the group consisting of cobalt fluoride, manganese fluoride, stannous fluoride, nickel fluoride and chromium fluoride as an additive results in an excellent nonlinear voltage property and a very excellent n-value 35 can be obtained by an additive which is fluoride with bismuth oxide, cobalt oxide or manganese oxide. Similar results can be obtained from combinations of two or more members of the group consisting of lead fluoride, barium fluoride and strontium fluoride with twO 40 or more members of the group consisting of cobalt fluoride, manganese @fluoride, stannous fluoride, nickel -fluoride and chromium fluoride or with bismuth oxide, cobalt oxide or manganese oxide as additives. For example, the addition of 0.5 mole percent of lead iluoride, 0.3 mole 45 percent of strontium fluoride and 0. 1 mole percent of cobalt fluoride to a zinc oxide body prepared as described above results in a 200 volt C-value at 1 ma. and an ii-value of 10.0. 50 TABLD, 3 Electrical Additlves (mole percent) characteilstics PbF2 COF2 MnFg SnF2 NiF2 CrF3 C (at I ma.) n r)5 0.05 0.05 ------------------------------ - 400 5.0 0.05 10 ------------------------------ :- 420 5.. 10 0.05 -------------------------------- 390 5.4 10 10 -------------------------------- 415 5.3 0.5 0.1 -------------------------------- 305 9.5 0,5 3 -------------------------------- 300 9.2 2 0.1 310 0.0(;0 2 3 -------------------------------- 290 9.4 0.5 0.5 -------------------------------- 190 13 0.05 -------- 0.05 ------------------------ 600 6.5 0.05 -------- 10 ------------------------ @-- 590 6.6 10 -------- 0.05 ------------------------ - 015 6.3 10 -------- 10 ------------------------ @600 6.8 (5 0.5 --- ---- 0.1 ------------------------ 450 10 0.5 -------- 3 ------------------------ 435 11 2 --- ---- 0.1 ------------------------ 440 11 2 -------- 3 ------------------------ 438 12 0.5 -------- 0.5 ------------------------ 285 16 0.05 ---------------- 0.05 ---------------- 350 4.0 0.05 ---------------- 10 ---------------- 365 5.3 70 10 ---------------- 0.05 ---------------- 348 5.0 10 ---------------- 10 ---------------- - 350 5.5 0.6 ---------------- 0.1 ---------------- 1.240 7.9 0.5 --- ------------ 3 ---------------- 245 8.1 2 -------------- 0.1 ---------------- 238 7.9 2 -------------- 3 ---------------- 261 8.0 0.5 ---------------- 0.5 ---------------- 165 10 7.5 TABLD 3-Gontlnue(I Additives (mole perceilt) - l@,lectrical ellaracteristies PbF2 CoPi2 MnFg SnF2 Niri2 CrF3 C (at I ma.) n 0.05 ---- 0.05 --- 360 5.1 0.05 ------- :: ------- 10 --- 370 5.3 lo -------- 0.05 -------- 373 4.9 lo -------- 10 -------- 362 5.0 0.5 ------------------------ 0.1 -------- 250 8.5 0.5 ------------------ 3 -------- 263 8.8 2 ------ : ----- :--- 0.1 ---- 255 9.0 2 ----------- : ------------- 3 :_--: ---- 260 8.9 0.5 ------------------------ 0.5 -------- 170 12 0.05 -------------- --------------- -- 0.05 650 7.3 0.05 -------------- : 10 635 7.2 10 ----------------- ::--@ ------------ 0.05 620 6.9 10 -------------------------------- 10 645 7.0 0.5 --- -------------------- 0.1 480 11 0.5 ------------ 3 495 10 -------------------------- 2 --- 0.1 473 11 2 ------------- : ------------------- 3 480 11 0.6 -------------------------------- 0.5 300 14 TABLE 4 Electrical Additives (mole perceilt) c haracteristics BaF2 COF2 MnF2 SnF2 NiF2 CrF3 C (at 1 ma.) n 0.05 0.05 -------------------------------- 620 6.2 0.05 10 -------------------------------- 600 6.1 10 0.05 -------------------------------- 590 5.9 10 10 --- ---- 575 6.4 0.5 o.i ----- : : 28r) 8.5 0.5 3 -------------------------------- 273 9.1 2 0.1 ----- : -------------------------- 290 9.3 2 s ----- -------------------------- 240 10 0.5 0.6 -------------------------------- 60 16 0.05 -------- 0.06 ------------------------ goo 9.0 0.05 -------- 10 ------------------------ 850 9.3 10 -------- 0.05 ------------------------ 843 8.5 10 ----- 10 ------------------------ 875 8.7 0.5 ----- 0.1 ------------------------ 420 12 0.5 ----- 3 ------------------------ 410 it 2 -------- 0.1 -------------- --------- 405 12 2 -------- 3 ------------------------ 410 13 0.5 -------- 0.5 ------------------------ 105 20 0.05 ---------------- 0.05 ---------------- 490 5.5 0.05 ---------------- 10 ---------------- 470 5.6 10 ---------------- 0.05 ---------------- 465 5.8 10 ---------------- 10 ---------------- 480 5.3 0.5 -------- 0.1 ---------------- 220 7.2 0.5 ------------- 3 ---------------- 216 8.0 2 ---------------- 0.1 ---------------- 200 8.3 2 -.@ -------- -- 3 ---------------- 232 7.9 0.5 ----------------- 0.5 ---------------- 55 12 0.05 ------------------------ 0.05 -------- 750 7.5 0.05 ------------------------ 10 -------- 690 5.0 10 ------------------------ 0.05 -------- 725 8.2 10 -------------- --------- 10 -------- 730 7.9 0.5 ------------------------ 0.1 -------- 193 11 0.5 --- 3 -------- 176 12 2 --------------------- 0.1 -------- 180 11 ------------ 2 ------------------------ 3 -------- 200 11 0.5 ------------------------ 0.5 -------- 70 15 - - 0.05 -------------------------------- 0.05 920 8.9 0.05 -------------------------------- 10 900 9.0 10 -------------------------------- 0.05 880 9.6 10 -------------------------------- 10 873 9.4 0.5 -------------------------------- 0.1 300 13 0.6 -------------------------------- 3 280 12 2 ------------------------------ 0.1 265 11 2 -------------------------------- 3 273 12 0.5 -------------------------------- 0.5 125 17 TABLE 5 Electrical Additives (mole perceiit) Cilaracteristies SrF2 COF2 MnF2 SnF2 NIF2 CrF3 C (at I ma.) 0.05 0.05 -------------------------------- 0.05 10 ----- -------- 295 5.9 ------------------ 330 6.2 10 0.05 -------------------------------- 310 6.8 10 10 -------------------------------- 290 5.8 0.3 0.1 -------------------------------- 145 10 0.3 3 -------------------------------- 130 10 3 0.1 -------------------------------- 150 11 3 3 -------------------------------- 128 10 0.5 0.5 -------------------------------- 42 14 0.05 --- 0.05 ------------------------ 600 7.3 0.05 -------- 10 ------------------------ 595 8.0 10 -------- 0.05 ------------------------ 610 7.5 10 -------- 10 ------------------------ 600 7.9 0.3 -------- 0.1 ------------------------ 235 12 0.3 -------- 3 ------------------------ 220 12 3 -------- 0.1 ------------------------ 205 13 3 -------- 3 ------------------------ 210 13 016 -------- 0.5 -------------- I --------- 70 15
[4]31658)725 7 TABL'D4 5 C!ontinued Additives (mole percent) Electrical characteristics SrF2 CoF2 mnr,2 SnP2 NiPi 2 CrF3 C (at 1 nia.) 0.05 ---------------- 0.05 ---------------- 350 68 0.05 ---------------- 10 ------------ --- 345 5:7 10 ---------------- 0.05 ---------------- 360 6.0 10 ---------------- 10 ---------------- 335 6.5 0.3 -------------- 0.1 ---------------- 190 10 0.3 ---------------- 3 ---------------- 1@50 11 3 ---------------- 0.1 ---------------- 175 10 3 3 ------ --------- 150 10 0.5 ---------------- 0.5 ---------------- 45 13 0.05 -------------- --------- 0.05 -------- 380 7.5 0.05 ----------------- ------ 10 -------- 375 5.0 10 ------------------------ 0.05 -------- 363 0.3 10 ------------------------ 10 -------- 395 71 0.3 ------------------------ 0.1 -------- 200 11 0.3 ------------------------ 3 -------- 205 11 3 ------------------------ 0.1 -------- 190 12 3 ------------------------ 3 -------- 185 11 0.5 ------------------------ 0.5 -------- 65 14 0.05 -------------------------------- 0.05 700 0.05 -------------------------------- 10 680 10 -------------------------------- 0.05 650 7.4 10 -------------------------------- 10 685 7.6 0.3 -------------------------------- 0.1 425 11 0.3 -------------------------------- 3 390 11 3 cl. 1 400 11 3 ------------------------------ 3 375 12 0.5 ------------------------------ 0.5 150 14 TABLE 6 Electrical Additives (mole percent) characteristics Fluoride Oxide C (at 1 ma,) n PbF2 0-5 Bi2O3 0.05 320 13 PbF2 0.5 Bi2O3 5 300 14 PbF2 2 Bi2O3 0.05 320 16 PbF2 2 Bi2o3 5 315 12 PbF2 0-5 Bi2O3 0.5 150 22 PbF2 0-5 coo 0.05 290 15 PbF2 0.5 coo 5 205 15 PbF2 2 CoO 0.05 300 18 PbF2 2 coo 5 335 15 PbF2 0-5 coo 0.5 130 24 PbF2 0.5 MnO 0.05 420 16 PbF2 0-5 MnO 5 415 17 PbF2 2 MnO 0.05 403 16 PbF2 2 MnO 5 395 16 PbF2 0.5 MnO 0.5 165 23 BaF2 0-5 Bi2O3 0-05 165 20 BaF2 0-5 Bi2O3 5 190 19 BaF2 2 B!203 0-05 186 15 BaF2 2 Bi2O3 5 185 21 BaF2 0-5 Bi2O3 0.5 65 29 BaF2 0.5 coo 0.05 180 20 BaF2 0.5 coo 6 168 15 BaF2 2 CoO 0.05 150 19 BaF2 2 coo 5 175 23 BaF2 0-5 coo 0.5 72 27 BaF2 0-5 MnO 0.05 240 17 BaF2 0.5 MnO 5 @>35 17 BaF2 2 MnO 0.05 250 19 BaF2 2 MnO 5 242 20 BaF2 0-5 MnO 0.5 90 26 SrF2 0.3 Bi2O3 0.05 160 16 SrF2 0.3 B!203 5 155 15 SrF2 3 Bi2O3 0.05 165 18 SrF2 3 Bi2O3 5 160 19 SrF2 0.5 Bi2O3 0.5 40 24 SrF2 0.3 coo 0.05 200 15 SrF2 0.3 coo 5 190 17 SrF2 3 coo 0.05 170 15 SrF2 3 coo 5 160 18 SrF2 0.5 coo 0.5 42 23 SrF2 0.3 MnO 0.05 300 14 SrF2 0.3 mno 5 285 17 SrF2 3 MnO 0.05 250 if) SrF2 3 mno 5 275 15 SrF2 0.5 MnO 0.5 85 24 E XAMPLE 4 a dditive, 0.05 to 10.0 mole percent of at least one member Zi nc oxide containing additives in the amounts set forth s elected fiom the group consisting of lead fluoride, barium in Table 7 is fabricated into resistors by the same proc7 0 fl uoride @nd strontium fluoride. e ss as that of Example 1. The resulting resistors are tested 2. A resistor as claimed in claim 1, wherein said sina ccording to the method used in testing electronic comte red body further includes 0.05 to 10.0 MOle percent of p onents parts. The load life test is carried out at 70' C. at least one member sel@cted from the group consisting a mbient temperature at 0.5 watt rating power for 500 of cobalt fluoride, manganese fluoride, stannous fluoride, hours. The beati@g cycle test is carried out by repeating 75 nickel fluoride and chromium fluoride. 8 5 times a cycle in which said resistors are kept at 85' C. ambient temperature for 30 minutes, cooled rapidly to -20' C. and then kept at such temperature for 30 minutes. Table 7 shows the difference in C-values and n-values after the load life test. It can be readily realized that the additives as listed in Table 7 are effective for improving the electrical and environmental stability. TABLE 7 Change rate (percent) 10 Load life test Heating cycle test Additives (mole percent) AC An AC All PbF2 0.5 CoF@ 0.1 -4.3 -5.5 - 2.1 -3.6 PbF2 0.5 CoF2 3 -3.2 -5.0 -1.0 -3.3 PbF2 2 CoF2 0.1 -2.6 -3.9 -1.3 -2.9 PbF2 2 CoF2 3 -2.1 -4.8 -1.2 -3.8 - PbF2 0.5 IvInF2 0.1 +0.1 -3.4 - 0.5 -5.0 PbF2 0-6 MnF2 3 -0.3 -3.9 - 0.8 -4.9 PbF2 2 MnF2 0-1 -2.1 -2.9 - 1.5 -5.1 PbF2 2 MnF2 3 -1.8 -2.7 - 1.3 -4.5 20 PbF2 0-5 SnF2 0,1 +0.1 -2.3 -1.0 -5.1 PbF2 0.5 SnF2 3 +0.3 -2.1 -1.3 -4.7 PbF2 2 SnF2 0,1 -0.1 -2.6 -2.8 -4.3 PbF2 2 SnF2 3 -0.4 -3.0 -3.3 -3.9 PbF2 0-5 NIF2 0.1 -3.5 -2.8 -3.8 -4.1 PbF2 0.5 NiF2 3 -2.8 -3.0 -2.9 -5.3 25 PbF2 2 NiF2 0,1 -4.0 -3.3 -4.3 -6.2 PbF2 2 NiF2 3 -3.4 -4.0 -3.0 -4.8 PbF2 0.5 CrF3 0.1 +0.1 -4.1 -1.2 -2.9 PbF2 0.5 CrFl 3 +0.2 -3.9 -2.0 -4.3 PbF2 2 CrF3 0.1 +0.1 -3.6 -1.7 -4.0 PbF2 2 CrF3 3 +1.0 -4.0 -1.0 -3.4 30 BaF2 0.5 CoF2 0-1 -1.6 -4.6 -2.0 -6.4 BaF2 0.5 COF2 3 -2.1 -5.2 -1.3 -2.8 BaF,32 COF' 0.1 -2.3 -4.8 - 1.2 -3.(5 BaF 2 CoF2 3 -1.8 -3.9 -1.4 -4.2 BaF2 0-5 MnF2 0-1 +0.1 -1.4 - 2.0 -4.3 ]3aF2 0.5 MiiF2 3 +0.3 -2.8 -2.1 -3.9 35 BaF2 2 MnF2 0-1 +1.0 -1.5 - 2.4 -4.1 BaF2 2 MnF2 3 -0.2 -2.0 - 3.0 -4.3 BaF2 0-5 SnF, 0,1 +0.1 -3.9 -2.8 -6.2 BaF2 0-5 SiiF2 3 -1.0 -4.1 -5.4 -5.9 BaF2 2 SnF2 0,1 -2.0 -3.8 -3.4 -4.1 BaF2 2 SnF2 3 +0.6 -4.1 -3.9 -4.8 4( BaF2 0.5 NiF2 0-1 -3.0 -5.6 -3.4 -6.0 BaF2 0.5 NiF2 3 -2.8 -7.1 -2.8 -6.2 ]3aF2 2 NiF2 0.1 -2.4 -6.3 -2.1 -6.3 BaF2 2 NiF2 3 -3.1 -5.9 -3.0 -5.8 BaF2 0-5 CrF3 0,1 +1.0 -3.8 -2.1 -3.9 BaF2 0-5 CrF3 3 +2.1 -2.9 -2.0 -4.0 BaF2 2 CrF3 0.1 +0.8 -1.9 -1.8 -3.7 45 BaF2 2 CrF3 3 +0.4 -2.3 -1.4 -4.1 SrF2 0.3 CoF2 0-1 -1.8 -4.0 -2.4 -4.3 SrF2 0.3 CoF2 3 -1.4 -3.8 -3.4 -4.2 SrF2 3 CoF2 0-1 -2.1 -3.6 -3.8 -5.0 SrF2 3 CoF2 3 -2.3 -3.9 -2.9 -5.1 50 SrF2 0.3 MnF2 0.1 -3.6 -4.5 - 1.5 -6.2 SrF2 0.3 MnF2 3 -4.0 -4.8 - 1.2 -7.3 SrF2 3 MnF2 0.1 -2.8 -6.0 - 3.6 -5.0 SrF2 3 MnF2 3 -2.2 -6.2 - 2.1 -4.1 SrF2 0.3 SnF2 0.1 +0.3 -2.4 -3.6 -6.2 SrF2 0.3 SnF2 3 +1.2 -3.1 -3.4 -7.1 55 SrF2 3 SnF2 0.1 -015 -4.0 -4.2 -5.0 SrF2 3 SnF2 3 -0.8 -1.9 -5.0 -4.3 S7F2 0.3 NiF2 0.1 -2.8 -4.2 -0.8 -6.1 SrF2 0.3 NIF2 3 -3.1 -5.0 -1.2 -5.8 SrF2 3 NiF2 0.1 -4.2 -4.1 -3.0 -4.1 SrF2 3 NiF2 3 -2.7 -3.9 -2.9 -3.9 Go SrF2 0.3 CrF3 0.1 -0.8 -3.4 -3.8 -7.1 SrF2 0.3 CrF3 3 -1.0 -2.9 -4.2 -5.8 SrF2 3 OrF@ 0.1 +0.8 -4.0 - 6.1 -3.4 SrF2 3 OrFs 3 +1.2 -5.1 -2.9 -6.2 What is
