Phase partitioning and uranium speciation in brannerite-based ceramics

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• 作者：S.V. Stefanovsky^a ; ^{serge.stefanovsky@mail.ru" class="auth_mail" title="E-mail the corresponding author} ; S.V. Yudintsev^b ; A.A. Shiryaev^a ; V.Y. Murzin^c ; A.L. Trigub^b ; ^d
• 关键词：Brannerite ; Ceramics ; Cerium ; Cold crucible ; Uranium
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：37
• 期：2
• 页码：771-777
• 全文大小：2482 K

文摘

Branneritecontaining ceramics were produced by cold pressing and sintering (CPS) and cold crucible inductive melting (CCIM) methods and examined by X-ray diffraction and absorption and by scanning electron microscopy. Brannerite content in the ceramics ranged between ∼20 and 90 vol.%. Uranium is mainly partitioned between brannerite and minor mixed U/RE oxide but since brannerite is a dominant phase, it takes up to 90% of total U. Uranium in the ceramics is present as U(IV) and U(V). In the low-brannerite ceramics U occurs as U(IV) whereas in the ceramics with brannerite as major phase U(V) dominates over U(IV). Ce in the brannerite ceramics is mainly trivalent. The first coordination shell of U in ceramics produced by CPS is split into two sub-shells with U-O distances of 1.7–1.9 Å and ∼2.1 Å while in the melted ceramics this interatomic distance is 2.1–2.2 Å. The next three atoms (Ti) are positioned at a distances of 3.1–3.2 Å.