RESISTIVITY, THERMOPOWER, AND SUSCEPTIBILITY OF RNIO3 (R = LA,PR)

We report the resistivity, thermopower, and dc susceptibility of RNiO3 (R = La,Pr) ceramic samples for 1. 4 K less-than-or-equal-to T less-than-or-equal-to 300 K. The resistivity of LaNiO3 shows a T2 dependence below 80 K and changes over to a T1.5 dependence at higher temperature (100-300 K). The resistivity of PrNiO3 exhibits a metal-insulator transition at T(MI) = 130 K with a linear temperature dependence above T(MI). The thermopower of both LaNiO3 and PrNiO3 is linear and negative in the metallic region. The susceptibility of LaNiO3 is Pauli-like with a Curie-Weiss contribution at low temperature. The Pauli term is enhanced well above the free-electron value. Our samples have smaller resistivity and larger resistivity ratio than previously reported. Thermogravimetric analysis shows that there is excess oxygen (delta > 0) in our samples of LaNiO3+delta, which suggests that the oxygen content of LaNiO3 is important for its physical properties.