Combined Rietveld refinement of Zn2SiO4:Mn2+ using X-ray and neutron powder diffraction data

The behavior of Mn2+ ions doped into the crystal lattice of Zn2SiO4 is closely related to the luminescent properties of Zn2SiO4:Mn2+ as a color-emitting phosphor. The combined Rietveld refinement using X-ray and neutron powder diffraction was used to determine the site preference and the amount of Mn2+ ions in Zn2SiO4:Mn2+. Of possible cation-disorder models, the best Rietveld refinement was obtained from the model that Mn2+ ions partially substituted for Zn2+ ions in two crystallographically non-equivalent Zn sites. The final converged weighted R-factor, Rwp, and the goodness-of-fit indicator, S (=Rwp/Re) were 8.12% and 2.28, respectively. The occupancy of Mn2+ ions for the two non-equivalent Zn sites was 0.034(4) and 0.003(2), respectively. The refined model described the crystal structure in space group R-3 (No. 148) with Z = 18, a (=b) = 13.9612(1) A, c = 9.3294(1) A and γ = 120 deg.