Synthesis,structure, and optical properties of a series of quaternary oxides,K2Ba(MO4)2 (M = Cr,Mo, W)

Single crystals of a family of quaternary oxides K₂Ba(MO₄)₂ (M = Cr, Mo, W) have been grown for the first time. The crystals were grown in a hydroxide-based hydroflux. The compounds crystallize in space group R $\overline{3}$m and, according to single-crystal X-ray diffraction structure determination, are isostructural with the mineral Palmierite. All compounds show anti-site mixing of the potassium and barium. The degree of mixing appears to be determined indirectly by the M-O bond distance. Diffuse reflectance spectra and room-temperature luminescence were measured for each compound.