X-ray photoelectron study of lanthanide borosilicate glass

Maslakov, K. I.; Stefanovsky, S. V.; Teterin, A. Yu.; Teterin, Yu. A.; Marra, James C.

doi:10.1134/s1087659609010039

Cited by 10 publications

(8 citation statements)

References 15 publications

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“…Computer simulation of experimental XANES spectrum of Pu L III edge in the glass studied provided the best fit when ~90% of total Pu existed as Pu(IV) and ~10% was present as Pu(III). This result was in a good agreement with reference data [2,14] and our XPS data [8], where almost all Pu was found to be in a tetravalent state. Magnitude of the Fourier transform (FT) of EXAFS spectrum at Pu L III edge shows that the peak due to first coordination sphere is much more intense than that of the second shell (Fig.…”

Section: Resultssupporting

confidence: 93%

“…The as-prepared glasses contained undissolved PuO 2 and those thermally-heated at 1250 C -PuO 2 -HfO 2 solid solution. In our previous work we have found that Pu in the LaBS glass is predominantly tetravalent [8]. The present work extends our investigations on determination of local environment of Pu and its analogue -Hf in the LaBS glass using X-ray absorption fine structure (XAFS) spectroscopy.…”

Section: Introductionsupporting

confidence: 77%

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XAFS of Pu and Hf L_III Edge in Lanthanide-Borosilicate Glass

Shiryaev

Zubabichus

Stefanovsky³

et al. 2009

MRS Proc.

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Lanthanide-Borosilicate (LaBS) glass capable to dissolve up to ~10 wt.% PuO 2 is designed for immobilization of plutonium-bearing wastes. The sample of LaBS glass with a target chemical composition (wt %): 9.0 SrO was prepared from PuO 2 powder and mechanically activated mixture of chemicals at 1500 C. The obtained product was visually homogeneous. Xray diffraction of the as-prepared glass showed that it mostly consists of a vitreous phase with small amounts of crystalline PuO 2 (or PuO 2 -HfO 2 solid solution with minor HfO 2 ), britholite and an oxide with a fluorite structure and a composition close to GdHfO 1.75 . The crystalline fraction increased after storage for ~1 year. Magnitude of the FT of EXAFS spectrum at Pu L III edge shows that the peak due to first coordination sphere is much more intense than that of the second shell. This indicates that though some Pu entered crystalline phases (mainly distorted PuO 2 ), its major fraction remained in the vitreous phase. Fit of the spectrum (R-factor = 0.02) gives the following distances: R (Pu-O 1 ) 1 = 1.98 Ǻ ( = 0.04), R (Pu-O 1 ) 2 = 2.18 Ǻ ( = 0.04), R (Pu-O 1 ) 3 = 2.35 Ǻ, R (Pu-Pu) = 3.72 Ǻ ( = 0.04), R (Pu-O 2 ) = 4.4 Ǻ ( = 0.06). Oxygen environment of the Pu 4+ ions in the vitreous phase resembles axially squeezed tetragonal pyramid with a coordination number ~5. The distances ~2.35 Ǻ and ~4.4 Ǻ correspond to the pairs Pu-O in the first and the second shells in the crystalline PuO 2 . The distance ~3.72 Ǻ corresponds to the Pu-Pu and/or Pu-M (M = Ln, Hf) distances. EXAFS spectra of Hf show that Hf is present mostly in the vitreous phase with major neighbors at 2.17 and ~3.2 A.

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Section: Resultssupporting

confidence: 93%

Section: Introductionsupporting

confidence: 77%

XAFS of Pu and Hf L_III Edge in Lanthanide-Borosilicate Glass

Shiryaev

Zubabichus

Stefanovsky³

et al. 2009

MRS Proc.

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“…The as-prepared glass contained minor britholite structure phase and traces of PuO 2 or/and PuO 2 -HfO 2 solid solution [6,8]. No appreciable changes in phase composition and texture of the glass were found after ~3 yrs of storage.…”

Section: Glass #1mentioning

confidence: 99%

“…Conventional borosilicate glasses have Pu solubilities in amounts of only up to ~2 wt.% [5]. In our previous works [6][7][8][9][10] we described the structure of the LaBS glasses both as-prepared and stored for a period of up to 2 years. The glasses had a tendency to devitrification with increase of storage time.…”

Section: Introductionmentioning

confidence: 99%

Electron Microscopy and Raman Spectroscopy Study of Pu-Bearing LaBS Glasses

et al. 2012

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Two LaBS glasses containing 9.5 wt.% (#1) and 5.0 wt.% PuO 2 (#2) were prepared by melting in Pt ampoules at 1500 C and examined by scanning electron microscopy with energy dispersive X-ray spectroscopy. The bulk of sample #1, both as-prepared and stored for 3 yrs, was amorphous with homogeneous PuO 2 distribution. Sample #2, especially after storage for 2-3 yrs, was partly devitrified primarily in the near-surface area. As followed from X-ray elemental maps, the vitreous phase was enriched with Al and Si whereas larger elongated and smaller dendrite crystals strongly enriched with rare earths (La, Nd, Gd) and Si and minor amounts of Hf may be attributed to britholite. A minor concentration of Pu was also observed in this phase. Moreover, relatively minor amounts of white regular crystals with high PuO 2 and lower HfO 2 contents were observed in the samples and are probably associated with PuO 2 and a PuO 2 -HfO 2 cubic solid solution phase. Nevertheless, even in devitrified areas of the samples, the majority of the Pu remained in the vitreous phase where it was homogeneously distributed.

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“…Stefanovsky and coworkers examined a Pu-bearing LaBS Frit X glass containing 9.5 wt % PuO 2 (Stefanovsky, 2007, Maslakov, 2009. In these studies, EXAFS, XANES, x-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy were used to determine the valence state and local structure of the glass.…”

Section: Local Environment Of Pu In Glassmentioning

confidence: 99%