Influence of nickel doping on oxygen-ionic conductivity of the n=1 Ruddlesden-Popper Phases La1.85Ca0.15(Cu1-xNix)O4-δ (δ=0.0905)

The results of the synthesis and characterization of the optimally doped La1.85Ca0.15(Cu1-xNix)O4-delta, solid solution with x = 0, 0.1, 0.2 and 0.3 are reported. The versatility of these La1.85Ca0.15(Cu1-xNix)O4-delta materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry. According to powder X-ray and neutron diffraction data, La1.85Ca0.15(Cu1-xNix)O4-delta adopts the tetragonal structure with oxygen vacancies occurring preferentially at the O-ap sites within the {(La/Ca)O) layers of the perovskite blocks and the oxygen deviation from stoichiometry delta was found to be delta=0.0905(6). The bulk conductivity indicated an Arrhenius-type thermally activated process and oxygen vacancies are the possible ionic charge carriers at T=270 degrees C. An increase of the conductivity was detected when Ni was introduced. With nickel ratio variation, a strong correlation was observed between the Cu(Ni)-O-ap apical bond length variation and the conductivity variation through controlling the O2- ion migration. (C) 2016 Elsevier Inc. All rights reserved.