The Positive Temperature Coefficient of Resistivity Effect in (1-x)KNbO3-xBaGeO3 Based Ceramics

(1-x)KNbO3-xBaGeO3 based PTCR ceramic materials are prepared using high purity K2CO3, Nb2O5, GeO2, Al2O3 and BaCO3 powders as starting materials, and the structural and electrical properties have been investigated. The results indicated that the samples doped with minute Ba as donor show excellent PTCR effect above the temperature of about 36°C. For the 0.40at% Ba-doped sample, the minimum resistance of 4.2×104Ω·cm, temperature coefficient (αk) of 24.37%/°C, PTCR anomaly lg(Rmax/Rmin) of 3.82 and transition temperature (Tmin) of 36°C are obtained.