Luminescence spectroscopy of Eu3+ in Ca3Sc2Si3O12

Ca3Sc2Si3O12 doped with 1 mol% Eu3+ and having a cubic garnet structure was prepared by a solid state reaction. The low temperature luminescence spectrum shows no measurable 5D0→7F0 band, in agreement with the location of the lanthanide dopant in a site of D2 symmetry, i.e. with a Ca2+ substitution. On the other hand, the spectrum is clearly dominated by the 5D0→7F4 band, which is significantly stronger than that for the other transitions originating from the 5D0 level. This unusual behavior is explained on the basis of a model describing the distortion of the EuO8 coordination polyhedron from a cubic geometry to the actual D2 one.