Characterization of electrical conductivity and temperature sensitivity of Cr/Sb-modified SnO_2 ceramics

摘要

To develop new system of thermal-sensitivity materials with the feature of negative temperature coefficient (NTC) of resistivity, Sb-doped SnO_2 (ATO) and Cr-modified ATO (Sn_(0.95-y)Sb_(0.05)Cr_yO_2 (y≤0.05)) ceramics are prepared. The phase component of the ceramics is analyzed by X-ray diffraction, and microstructures are observed by scanning electron microscope. The electrical conductivity and temperature sensitivity of the ceramics are investigated by analysis of the related resistance-temperature feature and complex impedance spectra (CIS). The results show that the Cr-modified ATO ceramics have excellent NTC performance, and the NTC materials constants of the ceramics can be conveniently adjusted from 1500 to 4500 K by changing the concentrations of Cr-ions. The calibration equations are adopted to fit the resistance-temperature plots of Sn_(0.93)Sb_(0.05)Cr_(0.02)O_2 ceramic with the Matlab program, and the results show that the Hoge-3 equation with 5 parameters has good fitting effect, indicating that it can satisfy the programing requirement for a temperature sensor well. By analyzing the CIS at different temperatures, the conduction mechanisms of the Cr-modified ATO ceramics are discussed.