Oxygen nonstoichiometry and some transport properties of LaSrNiO4-delta nickelate

Oxygen nonstoichiometry and electrical conductivity of LaSrNiO4-delta nicke late were investigated and oxygen permeability of LaSrNiO4-delta + 40% Ag c omposite ceramics was estimated. The oxygen content in LaSrNiO4-delta chang es from 3.99 to 3.45 in the temperature range 600-1000 degrees C at oxygen partial pressures 100 to 2 Pa. The decrease of oxygen content in nickelate takes place by removing it from vertexes of NiO6 octahedrons which form the perovskite layers within the lattice of nickelate. This causes an increase of the c parameter and a decrease of the a parameter of the tetragonal cel l of nickelate. The cell volume of the crystal remains constant. The nickel ate studied appeared to be p-type conductor with a metallic-like temperatur e function of the electrical conductivity. At the same experimental conditi ons the oxygen permeability of LaSrNiO4-delta + 40% Ag composite is lower b y a factor of 100 in comparison with the permeability of La2NiO4+/-delta an d La2NiO4+/-delta + 40% Ag composite. (C) 2000 Elsevier Science B.V. All ri ghts reserved.