材料期刊网

By analysing the EPR spectra of alpha-LiIO3:Cr3+ the defect models of a low temperature centre Cr3+L and two high temperature centres Cr3+H1 and Cr3+H2 are suggested. In centre Cr3+L, the Cr3+ ion replaces the Li+ ion and excess charge is compensated by two nearest Li+ vacancies on the same axis. In centres Cr3+H1 and Cr3+H2, the Li+ vacancies below and above the Cr3+ ion are, respectively, dissociated from the low temperature centre Cr3+L. The suggestions are supported by the theoretical calculations of EPR parameters D, g(parallel to) and g(perpendicular to) for the three Cr3+ centres. The reasonableness of these models is discussed.