Infrared spectra of iron phosphate glasses with gadolinium oxide

The structure of xGd2O3(40 − x)Fe2O360P2O5 (0 ⩽ x ⩽ 12 mol%) glasses have been investigated using Fourier transform infrared spectroscopy (FT-IR). The X-ray diffraction (XRD) and scanning electron microscope (SEM) for the samples containing 9 mol% Gd2O3 show the presence of a unique crystalline phase, GdPO4, embedded in an amorphous matrix. These results suggest that the solubility of gadolinium in these iron phosphate melts is less than 9 mol% Gd2O3. FTIR data suggest that the replacement of up to 6 mol% Fe2O3 by Gd2O3 in the 40Fe2O360P2O5 (mol%) glass does not produce any fundamental change in structure of the phosphate network, which consists of predominantly pyrophosphate groups with a small proportion of metaphosphate and orthophosphate groups. This suggests that Gd is substituted into Fe sites in phosphate network. From all these considerations we can conclude that Gd2O3 enters in the structure of studied glasses as a network modifier.