The perovskite CaMn x Zr (1- x ) O 3 ( x = 0, 0.05, 0.10, 0.15) (CMZO) NTC (Negative Thermal Coefficient) thermo-sensitive ceramic were prepared by the solid phase method that can be used as high temperature thermistor materials in the range of 200–1200 °C.The XRD pattern showed that CMZO is a finite solid solution and that a second phase, CaMnO 3 , will be formed after exceeding the solid solution limit (i.e., at x = 0.1). The thermal constant B value was found to decrease from 19521 K to 9217–9535 K, with a corresponding decrease in activation energy , E a , from 1.69 eV to 0.82 eV. The Nyquist plot indicates that the grain boundary resistance determines the overall complex impedance. Moreover, the aging drift rate (ΔR/R 0 ) was found to be lower than 4.3%, which is an indication of an excellent high temperature stability of the CMZO ceramic material.
Ma Panfei,Zhang Huimin,Chen Mingxing,Liu Ting,Chang Aimin,Su Zhi
Highly dense LaCrO 3 negative temperature coefficient (NTC) thermistor ceramics by low-heating solid-state method have been successfully synthesized in air ambient. The X-ray diffraction analysis has shown that both of the calcined powders and as-sintered ceramics crystallize in a perovskite structure. The relative densities of the ceramics synthesized by Cr(NO 3 ) 3 ·9H 2 O and the ceramics synthesized by CrCl 3 ·6H 2 O are 91% and 65%, respectively. The relationship between lnρ and 1000/T shows an approximate line in the measured temperature range. The values of ρ 25 and B 0/25 of the ceramics synthesized by Cr(NO 3 ) 3 ·9H 2 O and the ceramics synthesized by CrCl 3 ·6H 2 O are 424.8 Ω cm, 3252 K and 1835.9 Ω cm, 3636 K, respectively.
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