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.

Graphical abstractUsing 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 full-size imageDownload 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.