Effect of iron substitution in pyrochlore type semiconducting oxides: CaCe[sub 0.6]Mn[sub 0.4]Sn[sub 1−x]Fe[sub x]NbO[sub 7−δ] (x = 0, 0.2, 0.4 and 0.6) for high temperature NTC thermistor applications

Abstract

Iron substituted Pyrochlore structed semiconducting oxides, prepared by solid state reaction method, exhibit Negative Temperature Coefficient of Resistance (NTCR) behavior for a wide range of temperature from room temperature to 600°C. The impedance study of the system provided insight to the bulk or grain contribution in the electrical properties of the system. We were able to decrease the activation energy for conduction by Fe substitution and enhance the sensitivity values without affecting the thermistor constant considerably. The conductivity variation with temperature follows the Arrhenius relation.