Energy transfer from rare-earth element to Mn in (Ca,Sr)Ga2S4 compounds



For realizing a red-colour emission using SrGa2S4 compounds, Mn and rare-earth-element (REE) co-doping is tried. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra are measured using samples so prepared. As a result, enhancement of the Mn red emission is observed. Considering the 4f and 5d levels of REE in the host material, it is expected that the energy transfer from REE to Mn is caused by the weak coupling between the d levels of REE and Mn. Moreover, in the Ce co-doping case, another process is expected as a resonant energy transfer between the 4f–5d transition of Ce3+ and a certain transition of Mn2+. To specify the Mn2+ levels related to the resonant transfer, PL spectra of a Mn only doped CaGa2S4 single crystal and an undoped one are measured at low temperatures, though we could not find emission expected to be related to the resonant transfer. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)