Formation of defect-fluorite structured NdNiOxHy epitaxial thin films via a soft chemical route from NdNiO3 precursors

Abstract

A new phase of oxyhydride NdNiO_xH_y with a defect-fluorite structure was obtained by a soft chemical reaction of NdNiO₃ epitaxial thin films on a substrate of SrTiO₃ (100) with CaH₂. The epitaxial relationship of this phase relative to SrTiO₃ could be controlled by changing the reaction temperature. At 240 °C, NdNiO_xH_y grew with a [001] orientation, forming a thin layer of infinite-layer NdNiO₂ at the interface between the NdNiO_xH_y and the substrate. Meanwhile, a high-temperature reaction at 400 °C formed [110]-oriented NdNiO_xH_y without NdNiO₂.