Crystal structure of U1-yLnyO2-x (Ln = Gd, Er) solid solution

JOURNAL OF NUCLEAR MATERIALS

卷:556

Article

Van Mao, Pham^1,2  Arima, Tatsumi¹  Inagaki, Yaohiro¹  Idemitsu, Kazuya¹  Akiyama, Daisuke³  Nagai, Takayuki⁴  Okamoto, Yoshihiro⁴ 

[1] Kyushu Univ, Fac Engn, Dept Appl Quantum Phys & Nucl Engn, Nishi Ku, 744 Motooka, Fukuoka, Fukuoka 8190395, Japan

[2] Vietnam Elect EVN, 11 Cua Bac St, Ba Dinh Dist, Ha Noi City, Vietnam

[3] Tohoku Univ, Inst Multidisciplinary Res Adv Mat IMRAM, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi 9808577, Japan

[4] Japan Atom Energy Agcy JAEA, 765-1 Funaishikawa, Tokai, Ibaraki 3191184, Japan

关键词: UO2;    Burnable poisons;    Crystal structure;    XRD;    XAFS;    Synchrotron radiation;   

DOI  :  10.1016/j.jnucmat.2021.153189

来源: Elsevier

【 摘 要 】

The crystal structure was evaluated for U(1-y)Ln(y)O(2-x) (Ln = Gd, Er; y = 0-0.4) samples sintered at 1973 K for 8 h under Ar and Ar-10% H-2 atmospheres. The effect of LnO(1.5) doping on the crystal structure was investigated by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The structures were refined by Rietveld analysis of the XRD patterns. LnO(1.5) doping into UO2 reduced the lattice parameter of UO2-LnO(1.5) solid solutions up to 40 mol % LnO(1.5). The lattice parameters of these samples were comparable to those of stoichiometric (U,Ln)O-2.00 solid solutions, that is, the O/M ratios were close to 2.00. XAFS spectra in the X-ray absorption near edge structure region showed that higher U oxidation states of + 5 or + 6 formed, in addition to + 4. Extended XAFS indicated that the interatomic distances of U-O and Gd-O decreased with increasing y , whereas those of Er-O may not decrease monotonically. (C) 2021 Elsevier B.V. All rights reserved.

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