Effect of varying Nd2O3 contents on the structure and mechanical properties of the radioactive waste form: aluminosilicate glass-ceramics

The magmatic diagenetic environment was simulated by high-temperature melting and natural cooling. A series of glass-ceramics with different Nd2O3 contents were prepared by using complex component granite (aluminosilicate material). The phase evolution of the matrix at different temperatures was studied by X-ray diffraction (XRD). The structure of glass-ceramics was analyzed by infrared spectroscopy (IR) and scanning electron microscopy (SEM). The mechanical properties of glass-ceramics were also evaluated. The results showed that the glass transition of pure matrix begins at 1200 °C, and the sample with the highest degree of vitrification is obtained at 1500 °C. The addition of Nd2O3 promoted the melting of Fe3O4 crystal, resulting in the complete amorphous matrix when the Nd2O3 amount is in the range of 20–26 wt.%. With the further increase of Nd2O3 content, Nd-bearing feldspar first appeared. No raw material Nd2O3 was found, indicating that the formation of Nd-bearing feldspar may increase the carrying capacity of the material. The Gaussian fitting results showed that the glass-ceramic samples with Nd2O3 content of 29 wt.% are mainly composed of Q2 and Q3 structural units. In the EDS result, part of neodymium was clustered with small bright spots, while the spots were uniformly distributed on the sample surface as a whole. Meanwhile, the addition of Nd2O3 increased the mechanical properties of the samples (3.20 g/cm3, 8.33 GPa for the sample with 29 wt.% of Nd2O3). The results provide a strategy for the treatment of solid waste with radioactive residual actinides.