Study On Composition, Structure And Thermal Durability Of Lanthanum Iron Phosphate Glass

Iron phosphate glasses have good chemical durability, low meltingtemperature and low viscosity, are candidates for immobilizing highlevel nuclear wastes. Iron phosphate glasses may be more suitable thanborosilicate glasses which are the only glasses being used forimmobilizing high level nuclear wastes. In the family of iron phosphateglasses, a40mol%Fe₂O₃—60mol%P₂O₅glass has the best chemicaldurability. In this work, the CaO was used as modifier, the ironphosphate glass （40mol%Fe₂O₃—60mol%P₂O₅） as matrix. Using hightemperature melting—quenching method prepares glass samples. Theproperties of glasses have been investigated mainly by XRD、 DTA、 IRand Raman spectroscopy. The results are as follows:The glass formation range of the xLa₂O₃—（100-x）（0.4Fe₂O₃—0.6P₂O₅） series is about x≤4mol%. The structure of the glasses ispredominant by pyrophosphate （Q¹） units, along with a small proportionof orthophosphate （Q0） and metaphosphate （Q²） units. With the additionof La₂O₃content, the amount of Q¹decreasing, while the amount of Q²units increasing. The density, hardness and glass transition temperatureincreasing with the addition of La₂O₃content. These results indicate thatLa₂O₃can improve the mechanical properties of glass and strengthen theglass network. The thermal stability also improved by La₂O₃. Thechemical durability is still good.The glass formation range of the yLa₂O₃—（100-y）[0.1CaO—0.9（0.4Fe₂O₃—0.6P₂O₅）] series is about y≤3mol%. The properties ofyLa₂O₃—（100-y）[0.1CaO—0.9（0.4Fe₂O₃—0.6P₂O₅）] series is less than that of the xLa₂O₃—（100-x）（0.4Fe₂O₃—0.6P₂O₅） glasses, and the baseglass （40mol%Fe₂O₃-60mol%P₂O₅） is more suitable for immobilizingLa₂O₃.