METAL-SEMICONDUCTOR TRANSITION OF LA2NIO4+DELTA

The excess oxygen concentrations of La2NiO4+delta have been measured i n 0.00-6.06, 13.33-18.25, or 66.66-71.40 kPa of oxygen in the range 30 0-1273 K by the desorption method, The electrical conductivities of La 2NiO4+delta have been also measured in 1.33, 13.33, 66.66, or 101.33 k Pa of oxygen in the range 77.4-1273 K or under a helium atmosphere (1 atm) in the range 77.4-300 K. The mechanism of the metal-semiconductor transition of La2NiO4+delta is discussed on the basis of the excess o xygen concentration and the electrical conductivity data. The metal-se miconductor transition of La2NiO4+delta is explained by the carrier co ncentration and the activation energy changes associated with the inco rporation of excess oxygen. (C) 1997 Academic Press.