Molecular dynamics(MD) simulations were conducted to investigate the structural and chemical environment of aluminum in aluminophosphate glasses.Such glasses have the potential for application in the disposal of radio...Molecular dynamics(MD) simulations were conducted to investigate the structural and chemical environment of aluminum in aluminophosphate glasses.Such glasses have the potential for application in the disposal of radioactive fluoride waste from molten salt reactors(MSR).Due to the risks of studying these materials and the limitations of realistic research conditions,MD simulations were used as an alternative method to study the vitrification of radioactive fluoride waste.In the past decades,aluminophosphate glasses have been studied and they exhibit certain favorable properties for high-level radioactive waste management.This work focuses on the effects of fluorine addition on structural changes in the glass.We observed that glass with composition P_2O_5–Al_2O_3–Na_2O–CaO exhibited a good performance in immobilizing fluoride at low F concentrations(approximately under25 mol%).Significant changes were observed where PO_3F_2 units replaced PO_3F units in the glass.The fourcoordinated AlO_4 units were increasingly converted into five-coordinated [AlO_xF_y] with the increasing F content.The radionuclide Sr in the simulation had the tendency to form six-coordinated octahedrons in the glass.We conclude that the structural changes resulting from the fluoridewaste added to aluminophosphate glasses does not adversely affect their chemical stability at relatively low F concentrations,i.e.,under 25 mol%.Hence,the use of phosphate glasses is a potential alternative method of fluoride waste disposal.展开更多
基金supported by the Strategic Pilot Science and Technology Project of Chinese Academy of Sciences(No.XDA02050)
文摘Molecular dynamics(MD) simulations were conducted to investigate the structural and chemical environment of aluminum in aluminophosphate glasses.Such glasses have the potential for application in the disposal of radioactive fluoride waste from molten salt reactors(MSR).Due to the risks of studying these materials and the limitations of realistic research conditions,MD simulations were used as an alternative method to study the vitrification of radioactive fluoride waste.In the past decades,aluminophosphate glasses have been studied and they exhibit certain favorable properties for high-level radioactive waste management.This work focuses on the effects of fluorine addition on structural changes in the glass.We observed that glass with composition P_2O_5–Al_2O_3–Na_2O–CaO exhibited a good performance in immobilizing fluoride at low F concentrations(approximately under25 mol%).Significant changes were observed where PO_3F_2 units replaced PO_3F units in the glass.The fourcoordinated AlO_4 units were increasingly converted into five-coordinated [AlO_xF_y] with the increasing F content.The radionuclide Sr in the simulation had the tendency to form six-coordinated octahedrons in the glass.We conclude that the structural changes resulting from the fluoridewaste added to aluminophosphate glasses does not adversely affect their chemical stability at relatively low F concentrations,i.e.,under 25 mol%.Hence,the use of phosphate glasses is a potential alternative method of fluoride waste disposal.
