CTR Character of Metal-Silica Glass Composites

A new class of critical temperature resistor (CTR) was fabricated from metal/silica glass composites. The electrical resistivity of the composite with 20vol% of Ag filler suddenly decreased from 105 to 101Ω·m at about 300°C, in analogy with the CTR characteristic observed in VO2 ceramics. It was assumed that this phenomenon was due to the high thermal expansion of the conducting filler in a low-thermal-expansion matrix: as the temperature increased, the conducting filler particles expanded to come into contact with one to another, resulting in a drop of resistivity at a critical temperature. The critical temperature varied with both the kind and the amount of metal filler.