Materials having the resistance between those of insulators and conductors are called semiconductors. Some semiconductive ceramics have useful properties of increasing resistance against electric current when the temperature rises to a certain level (positive temperature coefficient). Murata was one the first to apply this property to succeed in mass production of PTC(positive temperature coefficient) thermistors for such applications as circuit protection. Murata also commercialized negative temperature coefficient thermistors, having a property of reduced resistance as the temperature rises, and widely used in temperature sensors and temperature compensators.