CTR character of metal-silica glass composites

A new class of critical temperature resistor (CTR) was fabricated from meta l/silica glass composites. The electrical resistivity of the composite with 20 vol% of Ag filler suddenly decreased from 10(5) to 10(1) Omega . m at a bout 300 degreesC, in analogy with the CTR characteristic observed in VO2 c eramics. It was assumed that this phenomenon was due to the high thermal ex pansion of the conducting filler in a low-thermal-expansion matrix: as the temperature increased, the conducting filler particles expanded to come int o contact with one to another, resulting in a drop of resistivity at a crit ical temperature. The critical temperature varied with both the kind and th e amount of metal filler.