Crystal structure of BaCa2MgSi2O8 and the photoluminescent properties activated by Eu2+

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-1 = 2.71% and R-F = 1.14%. BaCa2MgSi2O8 crystallizes in the trigonal space group P3ml (no. 164) with a = 5.430(3)angstrom and c = 6.807(2)angstrom. 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 oil 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. (c) 2008 Elsevier B.V. All rights reserved.