PURPOSE: To enlarge constant B of a thermistor, to reduce fluctuation of specific resistance and the constant B in high temp. atmosphere as high as about 500°C, and to enable its use for a long time period by sintering a mixture of NiO, ZnO, Fe2O3, and CuO of a particular compsn.
CONSTITUTION: After mixing NiO, ZnO, Fe2O3, and CuO in a ball mill and calcining provisionally at about 900°C, obtd. product is pulverized in the ball mill. Obtd. pulverized product is mixed with a binder and molded, then, the product is sintered by elevating the temp. to ca. 1200°C at ca. 200°C/hr temp. elevating rate. Thus, a compsn. for thermistor having 102-103 ohm.cm specific resistance and being expressed by the formula is obtd. (wherein 0<w<61; 0<x<50; 35≤y≤55; 4≤z≤12; w+x+y+z=100mol.%).
YONEDA YASUNOBU
BABA YUKIO
