Improved Nb–substituted La0.5Sr0.5CoO3 ceramics as new and low–cost functional materials for thick–film resistors

Abstract

The use of ruthenium oxides as a functional material for commercial thick–film resistors is not conducive to further lowering manufacturing costs. In this study, we propose Nb–substituted La0.5Sr0.5CoO3 (La0.5Sr0.5Co1-yNbyO3, LSCNb, y = 0.02–0.08) ceramics as new and low–cost functional materials for thick–film resistors. The conductivity and temperature coefficient of resistance (TCR) of the LSCNb samples sintered at different temperatures displayed similar downward trends with increasing Nb5+ content. A relatively high conductivity of 1670 S/cm and a minimum absolute TCR of −168 ppm/°C were attained for the sample with y = 0.06 sintered at 1225 °C. Furthermore, zero TCR was achieved for samples within the doping range of 0.05 < y < 0.06. The variation in density of states, electron density, and bond population could explain the change in electrical properties in the experiment. Additionally, the LSCNb ceramics showed good frequency stability. Therefore, the improved Nb–substituted La0.5Sr0.5CoO3 ceramics can be promising candidates for low–cost functional materials of thick–film resistors.