Crystal structure of BaCa2MgSi2O8 and the photoluminescent properties activated by Eu

Rietveld refinements of X-ray powder diffraction data have confirmed the crystal structure of BaCa₂MgSi₂O₈ prepared by a standard solid-state method. The final reliable factors were R_wp=10.91%, R_p=8.10%, R_I=2.71%, and R_F=1.14%. BaCa₂MgSi₂O₈ crystallizes in the trigonal space group P3¯m1 (no. 164) with a=5.430(3) Å and c=6.807(2) Å. The oxide has a layered structure constructed from the unit layers built up by corner-sharing MgO₆ octahedra and SiO₄ tetrahedra. Ba and Ca atoms occupy the distinct crystallographic sites; Ba atom is sited in the interlayer space and Ca atom is embedded in the layer framework. This structure was not disrupted by doping of Eu²⁺ ions.The Eu²⁺-doped BaCa₂MgSi₂O₈ exhibited an intense blue emission based on 5d-4f electron transitions of Eu²⁺ ions under 254 nm excitation. This emission has a sufficient chromaticity as a blue phosphor. An additional analysis of the emission spectra using an empirical formula indicates that Eu²⁺ is distributed into both Ba and Ca sites.