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Title: Effect of Na 2 O on aqueous dissolution of nuclear waste glasses

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 487; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-12-07 13:16:29; Journal ID: ISSN 0022-3115
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Citation Formats

Farooqi, Rahmat Ullah, and Hrma, Pavel. Effect of Na 2 O on aqueous dissolution of nuclear waste glasses. Netherlands: N. p., 2017. Web. doi:10.1016/j.jnucmat.2017.02.013.
Farooqi, Rahmat Ullah, & Hrma, Pavel. Effect of Na 2 O on aqueous dissolution of nuclear waste glasses. Netherlands. doi:10.1016/j.jnucmat.2017.02.013.
Farooqi, Rahmat Ullah, and Hrma, Pavel. Sat . "Effect of Na 2 O on aqueous dissolution of nuclear waste glasses". Netherlands. doi:10.1016/j.jnucmat.2017.02.013.
title = {Effect of Na 2 O on aqueous dissolution of nuclear waste glasses},
author = {Farooqi, Rahmat Ullah and Hrma, Pavel},
abstractNote = {},
doi = {10.1016/j.jnucmat.2017.02.013},
journal = {Journal of Nuclear Materials},
number = C,
volume = 487,
place = {Netherlands},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jnucmat.2017.02.013

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  • This paper reports the interesting results on mixed alkali effect (MAE) in xLi{sub 2}O-(30-x)Na{sub 2}O-69.5B{sub 2}O{sub 3} (5 {<=} x {<=} 28) glasses containing Fe{sub 2}O{sub 3} studied by electron paramagnetic resonance (EPR) and optical absorption techniques. The EPR spectra in these glasses exhibit three resonance signals at g = 7.60, 4.20 and 2.02. The resonance signal at g = 7.60 has been attributed to Fe{sup 3+} ions in axial symmetry sites whereas the resonance signal at g = 4.20 is due to isolated Fe{sup 3+} ions in rhombic symmetry site. The resonance signal at g = 2.02 is duemore » to Fe{sup 3+} ions coupled by exchange interaction. It is interesting to observe that the number of spins participating in resonance (N) and its paramagnetic susceptibility ({chi}) exhibits the mixed alkali effect with composition. The present study also gives an indication that the size of alkali ions we choose in mixed alkali glasses is also an important contributing factor in showing the mixed alkali effect. It is observed that the variation of N with temperature obeys Boltzmann law. A linear relationship is observed between 1/{chi} and T in accordance with Curie-Weiss law. The paramagnetic Curie temperature ({theta} {sub p}) is negative for the investigated sample, which suggests that the iron ions are antiferromagnetically coupled by negative super exchange interactions at very low temperatures. The optical absorption spectra exhibit only one weak band corresponding to the transition {sup 6}A{sub 1g}(S) {sup {yields}} {sup 4}A{sub 1g}(G); {sup 4}E{sub g}(G) at 446 nm which is a characteristic of Fe{sup 3+} ions in octahedral symmetry.« less
  • Moessbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO{sub 2}-CaO-ZnO-Na{sub 2}O-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Isomer shift values of the glasses suggest that Fe{sup 3+} and Fe{sup 2+} are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe{sup +3}/Fe{sup +2} ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distorted when the iron content is greater. X-ray diffraction measurements weremore » carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.« less
  • The complex conductivity spectra of mixed alkali borate glasses of compositions y [xLi{sub 2}O.(1-x)Na{sub 2}O].(1-y)B{sub 2}O{sub 3} (with x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0; y=0.1, 0.2, 0.3) in a frequency range between 10{sup -2}Hz and 3MHz and at temperatures ranging from 298 to 573K have been studied. For each glass composition the conductivities show a transition from the dc values into a dispersive regime where the conductivity is found to increase continuously with frequency, tending towards a linear frequency dependence at sufficiently low temperatures. Mixed alkali effects (MAEs) in the dc conductivity and activation energy are identified and discussed. Itmore » has been for the first time found that the strength of the MAE in the logarithm of the dc conductivity linearly increases with the total alkali oxide content, y, and the reciprocal temperature, 1/T.« less