Bi-doped germanium niobate glasses with near-infrared broad-band emission
掺Bi离子锗铌酸盐红外发光玻璃的研究

The Bi2O3 doped glasses with concentrations 5 of（0.9 - x） GeO2-xNb2O5-0.1BaO（x = 0.04,0.07,0.1） glasses are prepared by the conventional melting method.The differential thermal analysis（DTA） curves,the absorption spectra,the fluorescence decay curve and the X-ray photoelectron spectra are measured.The difference between glass crystallization onset temperature and transition temperature（Tx—Tg） of the glasses is up to 200℃from the DTA curve.Absorption peaks at 500,700,and 1000 nm are observed. The absorption edges show a red-shift with the increase of Nb2O5 content x.The emission band at 1300 nm with the full width at half maximum near 200 nm is observed under the excitation of 808 nm laser.The fluorescence intensity increases with the increase of the concentration 5 of Bi2O3.The fluorescence intensity reaches a maximal value when the concentration 8 of Bi2O3 is about 0.01.The peaks of binding energy in XPS are located at 159.6 and 164.7 eV respectively.The binding energy peaks are located between those of Bi3+ and Bi5+ by comparing with those of Bi2O3(Bi3+) and NaBiO3(Bi5+).According to the XPS results,one may conclude that Bi3+ and Bi5+ ions co-exist in the glass.The near infrared broadband emission may be assigned to Bi6+ ion based on the results of emission spectra and X-ray photoelectron spectra.The broadband intensity is gradually weakened as the Nb2O5 content x increases from 0.04 to 0.1.As GeO2 is substituted by NO2O5,complex NbGe defects are formed and the lower valence state of Bi ions will be inevitably formed to compensate the extra electric charge from Nb5+,thus resulting in the inhibition of Bi5+ and weakening the fluorescence aforementioned.