Local Environment and Electronic Structure in K2NiF4-type La2Li0.50Cu0.50O4 Doped by 57Fe

Abstract

The 57Fe M¨ossbauer spectrum of the oxide La2Li0.50Cu0.50O4 doped with 57Fe (1 at.-%) underlines at 300 K the presence of three different components: two corresponding to the substitution of 57Fe probe atoms for respectively “Cu3+” [Fe(1)] and Li+ [Fe(3)] and the third [Fe(2)] attributed to 57Fe associated with oxygen vacancies. A decrease of the temperature down to 77 K does not lead to essential changes of the M¨ossbauer parameters corresponding to the Fe(1) and Fe(2) sub-spectra. On the contrary, a drastic change occurs in the Fe(3) sub-spectrum which has been interpreted by a displacement of the charge-transfer equilibrium Fe4+(3) + O2− →Fe3+(3) + O(L) at the Li+ sites