LaNiO2: Synthesis and structural characterization

The preparation of a single phase LaNiO2 by controlled H2 reduction of the perovskite LaNiO3 is reported. The different steps of the synthesis are detailed. The structural characterization is made by X-ray diffraction (XRD) and neutron powder diffraction (NPD) and discussed; the derived crystal structure is the infinite-layer CaCuO2. Both XRD and NPD patterns are characterized by anisotropic shape broadening originating from size effect linked to the reduction process. From NPD, the LaNiO2 powder is composed of platelet-like crystallites having an average thickness equal to 20 nm along the [001] direction. A modulation of the neutron diffraction background is observed and discussed in connection to the reduction process.