Compositional dependence of the crystal symmetry of Eu3+-doped (SrxBa1−x)2CaWyMo1−yO6 phosphors

•Systematic study of the crystal structure of Eu3+-doped (SrxBa1−x)2CaWyMo1−yO6.•The Sr/Ba ratio was the main determinant for the crystal symmetry.•The structure evolved from Fm3¯m via I4/mI4/m to P21/nP21/n with increasing Sr content.•The results are in very good agreement with reported optical properties.

Two series of A-site and B-site Eu3+ doped (SrxBa1−x)2CaWyMo1−yO6 double perovskite phosphor materials were prepared via a modified Pechini sol–gel route; (SrxBa1−x)1.96Eu0.02K0.02CaWyMo1−yO6 and (SrxBa1−x)2Ca0.96Eu0.02Li0.02WyMo1−yO6 (x and y  =0, 0.25, 0.50, 0.75, 1). The Sr/Ba ratio was the main determinant for the crystal symmetry of the series, while variation in the W/Mo ratio did influence the crystal symmetry significantly. The crystal structure evolved with Sr/Ba ratio from cubic Fm3¯m for x  =0, via tetragonal I4/mI4/m for x  =0.25, to monoclinic P21/nP21/n for x≥0.5, as verified by Rietveld refinement of X-ray diffractograms as well as by Raman spectroscopy. The reported boundaries for the compositionally induced phase transitions are in very good agreement with reported optical properties.

Graphical abstractThe crystal structure of A- and B-site Eu3+-doped (SrxBa1−x)2CaWyMo1−yO6:Eu3+ is reported by systematic X-ray diffraction and Raman spectroscopy studies.Figure optionsDownload full-size imageDownload as PowerPoint slide