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.

The 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 as PowerPoint slide