SUPPRESSION OF METAL-SEMICONDUCTOR TRANSITION IN NDNIO3-DELTA SAMPLES DOPED WITH CU

The substitution of nickel by copper using a sol-gel method in NdNiO3 perovskite, which yields NdNi1-xCuxO3 (from x = 0.05 to x = 0.15), has been performed, These compounds present the same crystallographic structure as the parent compound. The doped compounds are metallic from 4.2 K to room temperature with a linear rho(T) behaviour and no metallic-insulator phase transition has been observed, even for the minimum Cu substitution (x = 0.05). Magnetic susceptibility curves show a paramagnetic behaviour with a Curie-Weiss term and an enhanced independent Pauli paramagnetism. The electrical transport and the magnetic behaviour suggest spin polaron formation.