Low temperature coefficient of resistance and high conductivity: Enhanced Cu–substituted LaCo0.4Ni0.6O3 ceramics for functional material

Abstract

The LaCo0.4Ni0.6-yCuyO3 (LCNCu, y = 0.02–0.08) ceramics were prepared and their possibility as a cheap alternative functional material for thick film resistors was studied. Scanning electron microscopy, differential–thermal and thermomechanical analyses showed that the incorporation of Cu2+ lowered the densification temperature and enhanced the compactness of LCNCu ceramics. All of the samples revealed relatively high conductivity. When y < 0.05, both Cu2+ substitution and sintering temperature showed a strong influence on the conductivity of LCNCu ceramics. However, the simulation results indicated that the density of states almost did not change after Cu2+ substitution despite the weakened electron transport. The temperature coefficient of resistance (TCR) gradually decreased with the addition of Cu2+. Low TCR values (absolute values < 300 ppm/°C) and high conductivity were realized for the samples with y ≤ 0.04 sintered at 1200 °C and y = 0.02 sintered at 1225 °C. Consequently, the improved LaCo0.4Ni0.6-yCuyO3 ceramics may be a potential economical functional material for thick film resistors.