Investigation of ion irradiation induced damages in iron phosphate glasses: Role of electronic and nuclear losses in glass network modification

Charu L Dube,M.C Stennett,N.C Hyatt,S Akhmadaliev

doi:10.1016/j.nocx.2020.100055

Abstract

Abstract Ion irradiation was used as a surrogate approach to mimic radiation induced modification in iron phosphate glass network. To understand the synergetic effect of electronic and nuclear energy losses in glass network modification, ions at different energies were employed. The iron phosphate glasses were irradiated with Au ions at different ion energies between 750 keV and 20 MeV. The ion beam irradiated samples were characterised by employing different techniques.The Fe L2,3- edge X-ray absorption spectra of irradiated samples reveal reduction of Fe3+ to Fe2+, induced by ion beam irradiation. X-ray diffraction and electron microscopy imaging confirm formation of crystalline Fe3(P2O7)2, Fe4(P2O7)3, Fe(PO)4, and Fe(PO3)3 phases. The origin of these crystalline phases may be attributed to induced stress in irradiated samples. The observed decrease in hardness of irradiated samples was attributed to formation of non-bridging oxygen.

Highlights

High-level nuclear wastes (HLW) require vitrification in suitable matrix prior to permanent disposal [1]
The Fe L2,3 X-ray absorption spectra for pristine and irradiated Iron phosphate glasses (IPG) samples were acquired in total electron yield mode on the Soft X-ray absorption spectroscopy (SXAS) Beamline 1 at the Indus 2 synchrotron, RRCAT, Indore
To investigate the effect of radiation induced changes on iron speciation in glass matrix, Fe L2,3 edge X-ray absorption spectra of pristine and irradiated iron phosphate glass (IPG) samples were acquired in total electron yield mode

Summary

Introduction

High-level nuclear wastes (HLW) require vitrification in suitable matrix prior to permanent disposal [1]. Radiation damage due to both nuclear and electronic stopping processes may be expected to affect the glass durability and its mechanical stability. During passage of ions through a solid, they deposit their energy through two interactions: (i) at low incident ion energy up to 100 keV, ions transfer their energy via elastic nuclear collisions/stopping (Sn), which is responsible for ballistic damage creation in solids, and (ii) at high energies, induce damage by inelastic electronic collisions/stopping [10]. Toulemonde et al have reported structural modification in vitreous SiO2 by Au (∼0.3–15 MeV) ion irradiation and the observed modification is explained with help of unified thermal spike model in elastic nuclear and inelastic electronic stopping regime [12]. Ion energies are chosen in different regime to study the synergetic effect of electronic and nuclear stopping on glass network modification

Experimental details

X-ray absorption spectroscopic measurements

Raman spectroscopic measurements

X-ray measurements and electron microscopic investigation

Hardness measurements

Conclusions