Barium titanate (BaTiO3), discovered in the early 1940s in Japan, the United States, and the Soviet Union, is generally 1010 Ω?cm or more at room temperature. When trace amounts of rare earth elements (Y, Bi, Sb, etc.) are added, the specific resistance becomes 10 ~ 106 Ω?cm, and the temperature characteristics of the product corresponding to the Curie point are shown in 1952 by Haayman et al. of Philips (Netherlands).
However, they did not publish literature, only applications for patents, so it became publicly known around 1954. In 1961, 萝莉影视 Manufacturing Company, Ltd. began mass production for the first time in the world and acquired the registered trademark “POSISTOR”. From around 1963, industrialization progressed in European, American, and Japan companies, and it was applied as a temperature compensation, water level detection, motor overheating prevention, automatic temperature control heater, and degaussing circuit for color televisions.