New high temperature NTC thermistors based on BaSm2Ti4O12 ceramics

In our research it is firstly found that BaSm2Ti4O12 (BSTO) ceramics only show negative temperature coefficient (NTC) effect in wide temperature range. The effects of sintering temperature on the microstructure and electrical properties of BSTO have been investigated. The relative density of as-sintered ceramics increases at first and then decreases with increasing sintering temperature. In the temperature of 400-850 degrees C, all samples show a linear relationship between the natural logarithm of resistivity and the reciprocal of temperature, indicating the NTC characteristics. The electrical resistivity decreases with increasing sintering temperatures. However, the activation energy Ea(400/850)degrees(C) and material constant B-400/850 degrees(C) decrease first and then increase, which are attributed to the variation of oxygen vacancy. The value of resistivity rho(400)degrees(C), Ea(400/850)degrees(C) and B-400/850 degrees(C) is in the range of 4.8x10(7)-1.43x10(8)Omega.cm, 1.33-1.41 eV and 15300-16400 K, respectively. This material has broad prospects in the field of high-sensitivity high-temperature thermistors research.