Microstructure and photoluminescence of Ge-doped mesoporous silica

Nanostructured Ge-doped mesoporous silica powder and thin film were prepared with a cetyltrimethylammonium bromide self-assembled template to investigate the doping effects on the structure and optical properties of mesoporous silica. The X-ray diffraction, transmission electron microscopy and photoluminescence (PL) results suggest that the Ge-doped mesoporous silica with Ge/Si molar ratio of 0.01 was characterized by the strongest PL intensity without phase separation. Worm-like Ge-doped porous silica with specific area up to 987 m2/g could be obtained in this study, in which some Si atoms were replaced by Ge atoms according to the X-ray photoelectron spectroscopy analyses. The PL intensity of mesoporous silica could be increased by germanium-induced oxygen-related defects, but for the samples with Ge/Si molar ratios larger than 0.01, the PL intensity decreased due to the phase separation of germanium oxide.