Effect of TeO 2 on Near‐Infrared Emission from Bismuth Centers in Borogermanate Glasses

Bi‐doped x TeO 2 –(60− x )GeO 2 –15B 2 O 3 –20MgO–5Al 2 O 3 glasses were prepared by the conventional melt‐quenching method and their absorption and fluorescence spectra were characterized. Broadband near‐infrared ( NIR ) emission from Bi centers centered around 1240 nm with a full width at half maximum ( FWHM ) of 250 nm was observed, and the position of the emission peak strongly depends on the excitation wavelength. Increasing TeO 2 concentration results in the strong coloration of the glass, leading to the reduction and finally, complete quenching of the NIR emission. Based on Raman, X‐ray photoelectron spectroscopy and transmission microscopy observation, the coloration of the glass at high TeO 2 concentration can be ascribed to the precipitation of elemental Te nanoparticles of around 3–8 nm, which effectively suppresses the NIR emission by reabsorption. The precipitation of Te nanoparticles in an oxide glass may find novel applications in photonics and relevant fields.