Multi-peak behavior of photoluminescence of silica particles heat-treated in hydrogen at elevated temperature

Pure nano-partical silica was prepared by sol-gel method, and then was treated in a H2 ambient at different temperatures. The surface structure and valence bonding of samples were analyzed with IR spectrum and X-ray induced photoelectron spectroscopy, respectively. Its photoluminescence property was studied with fluorescence spectroscopy. The results showed that only one luminescence band at 344 nm exists for silica heat-treated at 450 °C. Silica samples heat-treated at higher temperatures showed completely different luminescence comparing with the samples heat-treated at lower temperatures. Multi-peaks were found in the SiO2 samples heat-treated at temperatures higher than 700 °C, in which the luminescence peaks at about 379 and 392 nm are similar with the β bands in silica glass originated from the same defect center of two-fold coordinated silicon atoms, and the luminescence bands at about 493 and 528 nm are few reported. The intensity of the luminescence bands increase with the increase of heat treatment temperature from 700 to 900 °C.