Structural stability and optical properties of RENiO3 (RE = Sm, Nd and Pr) surface upon oxygen vacancy and adsorption

The oxygen vacancies and oxygen adsorptions frequently exist in the thin films of perovskite rare-earth nickelates (RENiO3) during the preparation process. In this paper, the models of RENiO3 slabs were constructed with oxygen vacancies and oxygen adsorptions, and first-principles calculations were conducted to reveal the atomic configurations, electronic structures and optical properties of RENiO3 slabs. The results show that the (0 0 1)pc surface is the most stable surface for pristine RENiO3 slabs. After introducing the oxygen vacancies and oxygen adsorption, SmNiO3 and NdNiO3 slabs transit from semiconductors to metals, while the PrNiO3 (1 1 1)pc slab remains semiconducting. In terms of optical properties, the visible light transmittance of RENiO3 slabs is much higher than that of the pristine bulk. In SmNiO3 (0 0 1)pc and PrNiO3 (1 1 1)pc slabs with oxygen vacancies, the mid-infrared transmittance is decreased and the visible light transmittance is increased, as compared to the slabs without oxygen vacancies. In NdNiO3 (1 1 1)pc slabs with oxygen adsorption, the mid-infrared transmittance is increased and the visible light transmittance is decreased, as compared to the slabs without oxygen adsorption. This study provides information of RENiO3 thin films with oxygen defects and their optical properties, which may help the experimental work on RENiO3 materials.