Study of the structural insertion of Al3+ in the Al2O3–SiO2 and Nd2O3–Al2O3–SiO2 glass systems

Abstract Glasses in the Al 2 O 3 –SiO 2 and Nd 2 O 3 –Al 2 O 3 –SiO 2 systems were prepared by the sol–gel method. The gel–glass evolution was studied using near-infrared (NIR) and ultraviolet–visible (UV–VIS) spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The results obtained indicate a relationship between the sample compositions, the treatment temperature and the Al coordination. In the samples of the Nd 2 O 3 –Al 2 O 3 –SiO 2 system the densification of the structure, when the treatment temperature increases, leads to the segregation of neodymium oxide particles.