The BaFe_(0.9)Sn_(0.1)O_(3)-BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)composite thick films were prepared by screen printing.X-ray diffraction(XRD)analysis confirms that the composite films are still composed of BaFe_(0.9)Sn_(0.1)O_(3)-BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)phases.For the prepared BaFe_(0.9)Sn_(0.1)O_(3)-BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)composite thick films,a linear relationship between the logarithmic resistivity and the reciprocal of the absolute temperature is observed,indicating an excellent NTC thermistor characteristic.The values of resistivity at 25℃,thermistor constant and activation energy,decreasing with BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)content increasing,are in the range of 8.9-92,990Ω·cm,1,126-3,777 K and 0.097-0.325 eV,respectively.Impedance analysis shows that at higher BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)content,the electrical properties of the composite films are mainly attributed to the contribution of grains and grain boundaries.With the gradual decrease of BaCo_(0.02)^(Ⅱ)Co_(0.04)^(Ⅲ)Bi_(0.94)O_(3)content,the grain boundaries affect strongly the electrical properties of the composite films.
Chang-Lai YuanYing LuoQin FengYun YangXiu-Juan ZhouXin-Yu Liu
