M. Takehana et al., ADDITIVES DISTRIBUTION AND ELECTRICAL-PROPERTIES IN ZINC-OXIDE VARISTOR PREPARED BY A WET CHEMICAL METHOD, The Korean journal of chemical engineering, 13(5), 1996, pp. 538-543
Cobalt-, praseodymium-added zinc oxide varistor was prepared through a
wet chemical method followed by sintering with or without calcination
. Changes in grain size, compact density, additives distribution, and
voltage-current/capacitance-voltage relations were investigated for th
e characterization of the samples sintered at temperatures from 1473 t
o 1573 K without calcination or with calcination al 773 K for 2 h. The
electrical properties were compared with those of samples prepared by
two types of ball mill methods. The wet chemical method provided almo
st the same additives-distribution profile and less impurities in comp
arison with the ball grinding method carried out for 10-100 h. The don
or concentration and the potential-barrier height for the samples were
evaluated by Double Schottky Barrier Model. Addition of small amount
of both cobalt and praseodymium in preparation by the wet chemical met
hod was effective for a better nonlinearity relation between voltage a
nd current, which has potential for a smaller sized varistor.