采用印刷法制备了CuO掺杂SrFe0.9Sn0.1O3-δ(CSFS)厚膜负温度系数(NTC)热敏电阻(掺杂量为20mol%~50mol%). 对其微观结构及电性能研究发现: 随着CuO掺杂含量的增加,厚膜表面变得更加致密, 室温电阻逐渐降低至0.46MΩ, 而热敏常数基本保持在3300K附近. CuO的加入导致SrFe0.9Sn0.1O3-δ分裂成多种铁含量更低的SrFe1-xSnxO3-δ物相(0.1<x<1). 借助两个串联的RQ等效部件组成的电路模型, 探讨了CuO含量为40mol%的SrFe0.9Sn0.1O3厚膜在25~250℃范围内的阻抗特征, 发现厚膜电阻主要是由晶界电阻和晶粒电阻构成, 且这两个贡献电阻都呈现出明显的NTC热敏效应. 此外, 阻抗虚部和电学模量虚部峰值对应频率的高度匹配表明厚膜的主要导电方式为局域导电机制.
CuO-doped SrFe0.9Sn0.1O3- δ (CSFS) thick-film negative temperature coefficient (NTC) thermistors ( 20mol%, 30mol%, 40mol%, 50mol% ) were prepared by the screen printing method. The microstructures and electrical prop erties of CSFS thick films were determined. With the increase of CuO content, the surface morphology of thick films becomes denser. The room-temperature resistance values gradually decreases to about 0.46 M Ω and the thermistor- constant values are basically constant at around 3300 K. After the addition of CuO, SrFe0.9Sn0.1O3- δ is decomposed into various SrFe1- xSn xO3- δ ( 0.1< x<1 ) phases. By two- RQ series equivalent circuit model, impedance characteristics of the thick film containing 40mol% CuO content are investigated over the measured temperature range of 25–250 ℃ . It is found that the total thick-film resistance is mainly attributed to the contribution of grain and grain boundary resistances, both of which show the typical NTC thermistor characteristics. Furthermore, the complete match of peak frequencies between the imaginary parts of impedance and electric modulus suggests that delocalized conduction is the main conduction mechanism in the thick-film NTC thermistors.
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