Effects of SnO<sub>2</sub> and Glass Particle Size on the Microstructure and the Electrical Properties of SnO<sub>2</sub>-Glass Composites

Abstract

The effects of the particle size of SnO2 and glass on the densification behavior, the microstructure and the electrical properties of SnO2-glass composites were examined. Moreover, the relationship between the electrical properties of the glass composites and the particle dispersion of SnO2 in a glass matrix was discussed following quantitative analysis of SnO2 particle dispersion by computer-assisted image analysis on SEM photographs. The results are summarized as follows: (1) when coarse grained SnO2 particles were used, the densification of the glass composites proceeded at low firing temperatures. Therefore, the use of coarse SnO2 particles was useful to get the glass composite having a high electrical conductivity and a small negative temperature coefficient of resistance (TCR) at low firing temperatures. However, after the completion of densification, the glass composite prepared using fine SnO2 particles showed a higher electrical conductivity and a smaller negative TCR because SnO2 particles were more highly crowded in a glass matrix and thus the SnO2 interparticle spacings were smaller than those of the sample dispersed with coarse SnO2 particles. (2) when fine glass particles were used, the densification of the glass composites proceeded at low firing temperatures and the particle dispersion of SnO2 in a glass matrix was homogeneous. Besides, the glass composite prepared using fine glass particles showed a high electrical conductivity and a small negative TCR at low firing temperatures. On the other hand, at high firing temperature, the glass composite having a higher conductivity and a smaller negative TCR was obtained when coarse glass particles were used, because the densely aggregated SnO2 particles formed highly conductive networks in a glass matrix.