ESR in Mn-doped cristobalite AlPO4

Abstract
ESR spectra are reported for powder samples of Mn-doped cristobalite AlPO4 heat treated in two different atmospheres: argon and air. The spectra are attributed to Mn2+ and Mn4+ ions, respectively. The temperature dependence of the spectrum intensities suggests that the Mn ions undergo a valence change that occurs in the same temperature range as the alpha - beta phase transition.