Thermally activated cation ordering in Zn0.5Mn0.5Ga2Se4 single crystals studied by Raman scattering

Trabajo presentado a la 16th International Conference on Ternary and Multinary Compounds (ICTMC-16), celebrada en Berlín (Alemania) del 15 al 19 de septiembre de 2008.Order/disorder phenomena in Zn0.5Mn0.5Ga2Se4 related to changes in the cation occupancies are studied by Raman scattering. The cation distribution can be modified by submitting the sample to a controlled heating and cooling cycle. Three different stages of order/disorder type were observed. On heating above an onset temperature of ≈250 °C, the partially disordered as-grown material (I -42m space group) evolves toward an ordered configuration with I -4 space group. At a temperature close to 500 °C the samples undergoes an order/disorder phase transition to a partially disordered structure that maintains the ordered stoichiometric vacancies. Slow cooling across the phase transition allows the cations to equilibrate and results in an almost fully ordered cation distribution at RT.Funded by: Spanish Government. Grant Numbers: MAT2007-64486-C07-02, MAT2007-61621.Peer Reviewe