Structure and luminescence of Cs2WO2F4: Efficient luminescence of isolated [WO2F4]−2 octahedra

The structure of Cs2WO2F4 was determined and refined to an R value of 6.8%. Cs2WO2F4 crystallizes in the trigonal space group P3m1 with a = 6.275(1)Å and c = 5.035(1)Å. The Cs ions are in 12-coordination and W in an octahedral 6-coordination. The oxyfluorotungstate octahedra are isolated in this structure and exhibit efficient luminescence under both UV and X-ray excitation at room temperature. The luminescence properties of Cs2WO2F4 are compared with those of Cs2WO2Cl4 and Ba2WO3F4.