Synthesis of the infinite layer Ni(I) phase NdNiO2+x by low temperature reduction of NdNiO3 with sodium hydride

The infinite layer Ni(I) containing phase NdNiO2+x (x = 0.03) has been synthesised by low temperature reaction between NdNiO3 and NaH: reduction with H-2 or metal gettering reagents does not afford this phase. The reaction path from the Ni(III) perovskite differs from the case of LaNiO2. Structural analysis by neutron powder diffraction reveals the environment around the Ni(I) cation is controlled by bond-length matching to the Nd3+ layers. Anisotropic broadening of the diffraction reflections is due to lamellar defects associated with the introduction of excess oxide anions between the corner-sharing square planar NiO2 sheets. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.