Metal-insulator transitions induced by doping in LaNiO3:: LaNi0.95Mo0.05O3 (M = Mo, W, Sb, Ti, Cu, Zn) perovskites

Structural characterization and electronic properties of the LaNi0.95M0.05O3 (M = Mo, W, Sb, Ti, Cu, Zn) perovskite-like system are reported. These compounds can be regarded as being derived from LaNiO3 by partial substitution of Ni3+ in this material by M6+, M5+, M4+, or M2+ formal cations, with a partial reduction of Ni3+ to Ni2+ taking place. X-ray powder diffraction data were analyzed by means of the Rietveld method and show that all the title materials present perovskite-type structure with a rhombohedral (S.G. R (3) over bar c) or orthorhombic (S.G. Pbnm) symmetry, depending on the nature of the M cation. In all cases, Ni and M cations are placed at random in octahedral B-sites of perovskite structure. Electrical resistivity measurements (four probe method) show metal-to-insulator (M-I) transitions for M = Mo, W, Ti, Cu, Zn at temperatures of about 50 K and a semiconductor behavior for the Sb sample in the whole temperature range explored. Magnetic susceptibility measurements show the presence of weak ferromagnetic interactions for M = Sb and Pauli paramagnetism for the remaining compounds. (C) 1998 Academic Press.