The metal-insulator transition in NdNi1-xCuxO3 perovskites

The perovskite oxides NdNi1-xCuxO3 have been synthesized for 0 ≤ x ≤ 0.2 under high oxygen pressure using a sol-gel method. Their structural, electrical, magnetic and calorimetric properties have been measured over a wide temperature range (4-300 K). All of the samples have an orthorhombic unit cell which does not change with Cu content. Nevertheless, their electrical properties change drastically with x from the very lowest values of x. The metal-insulator transition temperature decreases as x increases, up to x=0.03; for x≥0.03 the system is metallic for all temperatures. Moreover, the replacing of Ni with Cu atoms leads to magnetic disorder in the Ni sublattice. (author)