High-quality  single crystals were grown by the Czochralski method. The X-ray diffraction (XRD) patterns indicated that the obtained phase was  without any parasitic phase. The X-ray photoelectron spectroscopy (XPS) was recorded and used to analyze the electronic state of each element in  crystal. Emission spectra of pure  single crystal excited at different wavelength were measured at room temperature. According to a combination of absorption, emission and up-conversion spectra, the luminescence properties of  crystal were investigated in this paper. Particularly, more attention was paid to revealing the charge transfer (CT) transition and analyzing the luminescence mechanism in  single crystal. In addition, the CIE chromaticity coordinates were calculated on a basis of emission spectra. The approximate color temperatures were also obtained through the McCamy’s approximate formula.

XPS, charge transfer state, luminescence, CIE chromaticity coordinate, color temperature.