Elastic properties of rhombohedral, cubic, and monoclinic phases of LaNiO3 by first principles calculations

Abstract

By applying density functional theory (DFT) approximations, we present a first principles investigation of elastic properties for the experimentally verified phases of a metallic perovskite LaNiO3. In order to improve the accuracy of calculations, at first we select the most appropriate DFT approaches according to their performance in reproducing the low-temperature crystalline structure and the electronic density of states. Then, we continue with the single-crystal elastic constants and mechanical stability for the most common rhombohedral as well as high-temperature cubic and strain-induced monoclinic phases. Together with the calculated single-crystal elastic constants, the deduced polycrystalline properties, including bulk, shear, and Young’s moduli, Poisson’s ratio, Vickers hardness, sound velocities, Debye temperature, and anisotropy indexes, remedy the existing gap of knowledge about the elasticity of LaNiO3, at least from a theoretical standpoint. It turns out that all three considered structures are mechanically stable, behave in a ductile manner, and their overall anisotropy is not strongly pronounced. Besides, rhombohedral and monoclinic phases show a similar polycrystalline behavior indicating that LaNiO3 is able to retain its bulk mechanical properties when grown in thin-film form.