A comparative study of the crystallographic, magnetic and electrical properties of the Nd_1-xLa_xNiO_{3- delta} system

The synthesis and physical characterization of Nd_1-xLa_xNiO_{3- delta} (from x=0 to 1) samples are reported. Nd_1-xLa_xNiO_{3- delta} samples are orthorhombic for x<or=0.4 and rhombohedral for x>0.4. Resistivity and magnetic susceptibility measurements from 4.2 K to 300 K are also reported. The increase of La content up to x=0.4 induces the decrease of metal-insulator (MI) phase transition temperature and compounds with x>or=0.5 are metallic. The distortion degree of the ideal perovskite structure, directly related to the Ni-O-Ni angle, is correlated with the MI phase transition temperature. The metallic phase is characterized by a linear dependence of rho (T) with a residual resistivity that decreases with x, being near zero for LaNiO₃. The conductivity in the semiconducting phases at low temperatures follows a variable range hopping mechanism. The magnetic susceptibility shows a Curie-Weiss contribution from the Nd sublattice and a Pauli susceptibility of similar magnitude for all samples. The analysis of the experimental data shows large electronic correlations in these compounds.