Composition and conductivity of some nickelates

Abstract Oxygen nonstoichiometry and electrical resistance of a series of La 2− x Sr x NiO 4± δ solid solutions with x =0.0–1.4 were investigated in argon/O 2 ( p O 2 =1.5–286 Pa) within a temperature range of 20–1050°C. The oxygen permeability of gas tight ceramics was determined. Increasing strontium content from 0 to 0.4 was found to decrease the amount of weak bonded oxygen, which can be reversibly exchanged with oxygen in the gaseous phase ( T =250–550°C). The equilibrium values of oxygen nonstoichiometry and specific resistance of the nickelates with 0.0≤ x ≤0.5 were determined as functions of temperature and oxygen partial pressure. The nickelates studied appear to be p-type conductors. Oxygen permeability of nickelates with x =0–0.4 increases in accordance with the increasing range of the oxygen nonstoichiometry ( T >800°C, the p O 2 gradient is (0.21×10 5 to 200) Pa).