Structural and magnetic properties of LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4−δ spinels: A first-principles study

Structural and magnetic properties of LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4−δ are investigated using density-functional theory calculations. Results indicate that nonstoichiometric LiNi0.5Mn1.5O4−δ and stoichiometric LiNi0.5Mn1.5O4 exhibit two different structures, i.e., the face-centred cubic (Fd-3m) and primitive, or simple, cubic (P4332) space groups, respectively. It is found that the magnetic ground state of LiNi0.5Mn1.5O4 (P4332 and Fd-3m) is a ferrimagnetic state in which the Ni and Mn sublattices are ferromagnetically ordered along the [110] direction whereas they are antiferromagnetic with respect to each other. We demonstrate that it is the presence of an O-vacancy in LiNi0.5Mn1.5O4−δ with the Fd-3m space group that results in its superior electronic conductivity compared with LiNi0.5Mn1.5O4 with the P4332 space group. (interdisciplinary physics and related areas of science and technology)