Oxygen potential and defect structure of the solid solution, Mg-Gd-UO2

Takeo Fujino, Nobuaki Sato, Kohta Yamada, Manabu Okazaki, Kousaku Fukuda, Hiroyuki Serizawa, Tetsuo Shiratori

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

For solid solutions MgyGdzU1-y-zO2+x with y = 0.03, 0.06 and 0.10 and z = 0.142, oxygen potential, ΔḠO2, was measured as a function of O/M ratio (M = Mg+Gd+U) at temperatures between 1000°C and 1250°C. The O/M ratio which gives the steepest change of ΔḠO2 (referred to as GOM) was lowered with increasing magnesium concentration. The GOMs were 1.968, 1.940 and 1.914 for 3, 6 and 10 mol% Mg, respectively. There seemed to be no temperature dependence of GOM. As the oxygen partial pressure, pO2, decreases, a part of the magnesium atoms rearrange from the substitutional 4a sites of Fm3̄m to the interstitial 4b sites as shown by density measurements, during which the magnesium solubility decreases from y = 1/3 to the minimum (<0.06) at around pO2 = 10-3 Pa. However, at pO2 = 10-8 Pa, the solubility again increases to >0.1. The ratio of interstitial magnesium to total magnesium was near 0.5 at 3-5 mol% Mg at GOM. The change rates of lattice parameter were found to be ∂a/∂x = -0.101 Å, ∂a/∂y = +0.290 Å for interstitial magnesium and ∂a/∂z = -0.187 Å.

Original languageEnglish
Pages (from-to)270-280
Number of pages11
JournalJournal of Nuclear Materials
Volume289
Issue number3
DOIs
Publication statusPublished - 2001 Mar
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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