LOW-TEMPERATURE ELECTRONIC-PROPERTIES OF THE LA(N+1)NI(N)O(3N+1) (N=2, 3, AND INFINITY) SYSTEM - EVIDENCE FOR A CROSSOVER FROM FLUCTUATING-VALENCE TO FERMI-LIQUID-LIKE BEHAVIOR

Measurements of the temperature dependence of the electrical resistivity rho(T), magnetic susceptibility chi(T), and Seebeck coefficient S(T) have been carried out on the n = 2, 3, and infinity members of the homologous lanthanum nickel oxide systems Lan+1NinO3n+1 that were annealed in air. With increasing n, a progressive decrease in the electrical resistivity and a gradual change from insulating to metallic behavior are observed. La3Ni2O7 is normetallic, showing a gradual increase in rho when T decreases (drho/dT < 0) from 300 to 4.2 K, whereas La4Ni3O10 and LaNiO3 exhibit metallic resistivity (drho/dT > 0). A minimum in rho(T) near 140 K is observed for La4Ni3O10, while LaNiO3 exhibits a T2 dependence for rho(T) below approximately 50 K. The magnetic susceptibility of LaNiO3 is Pauli-like, but the chi(T) data for La3Ni2O7 and La4Ni3O10 below 350 K show a decrease with decreasing temperature. The Seebeck coefficient of all these compounds is negative at high temperatures; La3Ni2O7 and La4Ni3O10 exhibit a sign change in S at low temperatures. These results suggest a crossover from a fluctuating-valence to a Fermi-liquid-like behavior with increasing n. (C) 1994 Academic Press, Inc.