Preparation and characterization of glass composite using metal particles coated with semiconductive SnO₂ fine particles obtained via sol—gel method

Abstract

SnO₂—glass composites are promising materials for nitrogen-fireable thick film resistor systems. However, the SnO₂—glass composite has many undesirable properties which should be improved for industrial application, such as a high electrical resistivity and a large negative temperature coefficient of electrical resistance. This work was undertaken to make a survey of the methods for improvement in the electrical properties of the SnO₂—glass composites. The effect of the addition of Cu particles, with a large positive temperature coefficient of electrical resistance, on the electrical properties of SnO₂—glass composites has been investigated. Cu particles have been coated with semiconductive SnO₂ fine particles by hydrolysing tin and antimony ethoxides then firing. The coated particles have been applied as conductive components in the glass composite. Using SnO₂-coated Cu particles, Cu and SnO₂ particles are homogeneously dispersed in a glass matrix, and the electrical properties of the glass composites largely depend on the volume fraction of Cu in the glass composite. The volume fraction of Cu in the glass composite is determined by a Cu/SnO₂ volume ratio in the coated particles. From the experimental evidence, it is thought feasible to produce the glass composite having well-controlled electrical properties by the suitable selection of the Cu/SnO₂ ratio in the coated particles.