Optical and structural characterization of colored Bi4Ge3O12 crystals

The red and white Bi4Ge3O12 (BGO) crystals had been grown by Vertical Bridgman (VB) method. The absorption and photoluminescence (PL) spectra of these BGO samples were measured. The red BGO shows a significant emission band peaking around 1490 nm under 808 nm laser diodes (LDs) excitation, and the white BGO exhibits a broadband emission under 940 nm LDs excitation. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to determine the structure of these BGO samples. The XAFS spectra indicated that the Bi environment in red and white BGO seem to be a little disordered compare with ordinary BGO.