ELECTRONIC CONDUCTIVITY IN THE LA(CR, NI)O3 PEROVSKITE SYSTEM

Electrical conductivity measurements were carried out in the LaCr1-xNixO3 system by a four-point dc method. The conductivities of LaCrO3 and LaNiO3 are 0.016 and 1000 OMEGA-1 cm-1 at room temperature and 0.759 and 250 OMEGA-1 cm-1 at 1000-degrees-C, both in flowing oxygen. The sample densities are 72 and 52% of the theoretical value, respectively. LaCrO3 is a semiconductor; LaNiO3 shows metallic conductivity behavior. Electrical conductivity measurements on solid solutions of these end members show that the transition from semiconducting to metallic conduction behavior occurs at the composition x = 0.79 +/- 0.04. The density of the solid solution samples ranges from 47 to 72% of the theoretical value. The electrical conductivity shows a linear dependence on the density that allowed us to normalize all conductivity data to 60% of theoretical density.