Exploration on anion ordering, optical properties and electronic structure in K3WO3F3 elpasolite

Room-temperature modification of potassium oxyfluorotungstate, G2-K3WO3F3, has been prepared by low-temperature chemical route and single crystal growth. Wide optical transparency range of 0.3–9.4 μm and forbidden band gap Eg=4.32 eV have been obtained for G2-K3WO3F3 crystal. Meanwhile, its electronic structure has been calculated with the first-principles calculations. The good agreement between the theorectical and experimental results have been achieved. Furthermore, G2-K3WO3F3 is predicted to possess the relatively large nonlinear optical coefficients.

Using the cm-size K3WO3F3 crystal (left upper), the transmission spectrum (right upper) and XPS valence electronic states (left lower) were measured, agreed with the ab initio results (right lower).Figure optionsDownload as PowerPoint slideHighlights
► The cm-size G2-K3WO3F3 single crystals are obtained.
► Optical absorption edge and transmission range are defined for G2-K3WO3F3 crystal.
► Crystal structures of all known K3WO3F3 polymorph modifications are determined.
► Experimental electronic structure is consistent with the first-principles result.
► G2-K3WO3F3 is predicted as a crystal with large NLO coefficients.