I. Bardez, D. Caurant, P. Loiseau, N. Baffier, J. Dussossoy, C. Gervais, F. Ribot, D. Neuville
Local environments of rare earth ions are studied in a rare earth rich glass (Glass A wt%: 51.0SiO 2 -8.5B 2 O 3 -12.2Na 2 O-4.3Al 2 O 3 -4.8CaO-3.2ZrO 2 -16.0RE 2 O 3 with RE=Nd or La) developed for radioactive waste immobilisation. The aim is to determine the structural environment of rare earths in this glass according to their concentrations, and to study the influence of the peralkaline or peraluminous character of the glass on these environments. To achieve this objective, two series of glasses were prepared from Glass A. The first one contains variable amounts of rare earth oxide (from 0 to 30 wt% RE 2 O 3 ) and the second one is a series of peralkaline (R>50%) and peraluminous (R<50%) glasses, with R=([Na 2 O]+[CaO])/([Na 2 O]+[CaO] +[Al 2 O 3 ]) at fixed RE 2 O 3 contents (16 wt%). The coupling of characterisation methods such as EXAFS (extended x-ray absorption fine structure) spectroscopy at the neodymium L I I I -edge, optical absorption spectroscopy, Raman spectroscopy and 1 1 B, 2 9 Si and 2 7 Al MAS-NMR, enables discussion of several hypotheses concerning both the nature of rare earth neighbourhoods and the glassy network structure.
研究了用于放射性废物固定化的富稀土玻璃(玻璃a wt%: 51.0 sio2 -8.5 b2o3 -12.2 na2o3 -4.3 al 2o3 -4.8CaO-3.2ZrO 2 -16.0 re2o3, RE=Nd或La)中稀土离子的局部环境。目的是根据其浓度确定该玻璃中的稀土结构环境，并研究玻璃的过碱性或过铝质性质对这些环境的影响。为了实现这一目标，用玻璃a制备了两个系列的玻璃。第一个系列含有可变量的稀土氧化物(从0到30 wt%的re2o3)，第二个系列是在固定的re2o3含量(16 wt%)下，R=([Na 2o]+[CaO])/([Na 2o]+[CaO] +[Al 2o3])的过碱性(R>50%)和过铝质(R<50%)玻璃。耦合表征方法，如EXAFS(扩展x射线吸收精细结构)光谱在钕L I I I I边缘，光学吸收光谱，拉曼光谱和11 B, 2 9 Si和2 7 Al MAS-NMR，能够讨论关于稀土邻域性质和玻璃网络结构的几个假设。
{"title":"Structural characterisation of rare earth rich glasses for nuclear waste immobilisation","authors":"I. Bardez, D. Caurant, P. Loiseau, N. Baffier, J. Dussossoy, C. Gervais, F. Ribot, D. Neuville","doi":"10.1557/PROC-807-157","DOIUrl":"https://doi.org/10.1557/PROC-807-157","url":null,"abstract":"Local environments of rare earth ions are studied in a rare earth rich glass (Glass A wt%: 51.0SiO 2 -8.5B 2 O 3 -12.2Na 2 O-4.3Al 2 O 3 -4.8CaO-3.2ZrO 2 -16.0RE 2 O 3 with RE=Nd or La) developed for radioactive waste immobilisation. The aim is to determine the structural environment of rare earths in this glass according to their concentrations, and to study the influence of the peralkaline or peraluminous character of the glass on these environments. To achieve this objective, two series of glasses were prepared from Glass A. The first one contains variable amounts of rare earth oxide (from 0 to 30 wt% RE 2 O 3 ) and the second one is a series of peralkaline (R>50%) and peraluminous (R<50%) glasses, with R=([Na 2 O]+[CaO])/([Na 2 O]+[CaO] +[Al 2 O 3 ]) at fixed RE 2 O 3 contents (16 wt%). The coupling of characterisation methods such as EXAFS (extended x-ray absorption fine structure) spectroscopy at the neodymium L I I I -edge, optical absorption spectroscopy, Raman spectroscopy and 1 1 B, 2 9 Si and 2 7 Al MAS-NMR, enables discussion of several hypotheses concerning both the nature of rare earth neighbourhoods and the glassy network structure.","PeriodicalId":20166,"journal":{"name":"Physics and Chemistry of Glasses","volume":"45 1","pages":"320-329"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89342549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-03-10DOI: 10.1142/S0217984902003634
P. Prakash, A. Murali, J. Rao
Electron paramagnetic resonance and optical absorption spectra of Fe 3+ ions in 85M 2 B 4 O 7 . (15-x)TeO 2 , xFe 2 O 3 [(M=Li, Na or K); 0.5≤x≤10 mol%] glass systems have been studied. The EPR spectra of all glasses exhibit three resonance signals at g=2.0, g=4.2 and g=6.4. EPR spectra of 3 mol% Fe 2 O 3 doped lithium borotellurite glass system were studied at various temperatures. The intensity of the resonance signals decreases with increase in temperature whereas linewidths are found to be independent of temperature. EPR spectra exhibit a marked concentration dependence on iron content. A decrease in intensity for the resonance signal at g=4.2 with increase in iron content for more than 3 mol% has been observed and this has been attributed to the formation of clusters in the glass samples. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/X versus T graph. The optical absorption spectrum exhibits five bands characteristic of Fe 3+ ions in a distorted octahedral symmetry. From the observed band positions, the crystal field parameter, Dq. and the Racah interelectronic repulsion parameters, B and C, have been evaluated. The optical band gap energy was found to decrease with increase in iron content which indicates that the nature of the glasses become more semiconducting with increase of iron content.
{"title":"EPR and optical absorption studies on Fe3+ ions in alkali borotellurite glasses","authors":"P. Prakash, A. Murali, J. Rao","doi":"10.1142/S0217984902003634","DOIUrl":"https://doi.org/10.1142/S0217984902003634","url":null,"abstract":"Electron paramagnetic resonance and optical absorption spectra of Fe 3+ ions in 85M 2 B 4 O 7 . (15-x)TeO 2 , xFe 2 O 3 [(M=Li, Na or K); 0.5≤x≤10 mol%] glass systems have been studied. The EPR spectra of all glasses exhibit three resonance signals at g=2.0, g=4.2 and g=6.4. EPR spectra of 3 mol% Fe 2 O 3 doped lithium borotellurite glass system were studied at various temperatures. The intensity of the resonance signals decreases with increase in temperature whereas linewidths are found to be independent of temperature. EPR spectra exhibit a marked concentration dependence on iron content. A decrease in intensity for the resonance signal at g=4.2 with increase in iron content for more than 3 mol% has been observed and this has been attributed to the formation of clusters in the glass samples. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/X versus T graph. The optical absorption spectrum exhibits five bands characteristic of Fe 3+ ions in a distorted octahedral symmetry. From the observed band positions, the crystal field parameter, Dq. and the Racah interelectronic repulsion parameters, B and C, have been evaluated. The optical band gap energy was found to decrease with increase in iron content which indicates that the nature of the glasses become more semiconducting with increase of iron content.","PeriodicalId":20166,"journal":{"name":"Physics and Chemistry of Glasses","volume":"18 1","pages":"102-107"},"PeriodicalIF":0.0,"publicationDate":"2002-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81990407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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