Method of producing homogeneous zno non-linear powder compositions

Abstract

A method of making a ZnO powder composition, which can exhibit non-linear V-I characteristics, comprises the steps of: (1) mixing about 75 mole % to about 98 mole % of small, finely divided, solid ZnO and about 2 mole % to about 25 mole % of at least one small, finely divided, solid additive oxide effective to produce nonlinear characteristics, with an aqueous binder solution comprising an organic, water soluble fugitive binder, to provide a slurry; (2) simultaneously drying, mixing and agglomerating the slurried solids into a mass of larger substantially spherical particles containing the finely divided solids and binder; (3) pressing a mass of the agglomerated particles, to provide a cohesive pressed green body; and then (4) heating the pressed body, first at a temperature rate increase effective to slowly decompose and remove the fugitive binder from the body and then heating at a temperature of between 1,050.degree. C. to about 1,400.degree. C. for a time effective to sinter together the particles of the body, forming ZnO grains; (5) crushing the sintered body to provide finely divided powder particle fragments; (6) passing the particle fragments through a means to measure particle size in a manner effective to provide at least two attached ZnO grain fragments per particle, to provide a non-linear ZnO powder; and optionally, (7) heating the non-linear ZnO particles at a temperature of between 500.degree. C. and 1,050.degree. C. and breaking up any agglomerates, to provide a finely divided powder which will exhibit non-linear V-I characteristics.