Homogeneity of peraluminous SiO2-B2O3-Al2O3-Na2O-CaO-Nd2O3 glasses: Effect of neodymium content

Abstract Considering the interest of developing new glass matrices able to immobilize higher concentration of high level nuclear wastes than currently used nuclear borosilicate compositions, glasses containing high rare earth contents are of particular interest. This study focuses on a peraluminous aluminoborosilicate system SiO 2 –B 2 O 3 –Al 2 O 3 –Na 2 O–CaO–Nd 2 O 3 defined by a peralkaline/peraluminous ratio R P  = ([Na 2 O] + [CaO])/([Na 2 O] + [CaO] + [Al 2 O 3 ])  2 O 3 from 0 to 10 mol% were studied using DSC, XRD, SEM, TEM, STEM and EMPA methods. The glasses present a high thermal stability even after a slow cooling treatment from the melt. Only a slight mullite crystallization is detected for low Nd 2 O 3 content (≤ 2.3 mol%) and crystallization of a neodymium borosilicate crystalline phase combined to a phase separation occurred at high Nd 2 O 3 content (≥ 8 mol%). The solubility of neodymium in the presence of aluminum is demonstrated, with higher neodymium incorporation amounts than in peralkaline glasses.