Stoichiometry of LiNiO_2 Studied by Moessbauer Spectroscopy

摘要

From the~(61) Ni and ~(57)Fe Moessbauer spectroscopy data follows the cationic site assignment in Li_(1-x)Ni_(1+)O_2. Our data explain the ferromagnetic properties of this material because of the appearance of Ni~(2+) (S = 1) among Ni~(3+) (S = 1/2) in Ni~(3+)O_2 hexagonal planes. We have no evidence for the ferromagnetic interaction between the NiO_2 layers through the excess Ni~(2+) ions substituting the Li~+ ions. The presence of Ni~(2+) found in the Ni~(3+)O_2 planes explains the absence of the Jahn-Teller distortions probably because of the electronic transfer between the Ni~(3+) and Ni~(2+) ions.