Description and classification of uranium oxide hydrate sheet anion topologies

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1996.0387· OSTI ID:459835

Miller, M L ^[1]; Finch, R J ^[2]; Burns, P C; Ewing, R C ^[1]

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1. Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
2. Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

The sheets of uranyl ions (U{sup 6+}O{sub 2}){sup 2+} in the structures of all uranyl oxide hydrates (UOH) (and the structurally related {alpha}- and {beta} forms of U{sub 3}O{sub 8}) are based on only four structural unit chains. Each sheet type may be reduced to its underlying sheet anion topology to determine the chains present within each topology and to describe the structural relationships among these phases. Each sheet type is described by a chain stacking sequence. The four chain types required to construct the UOH sheet anion topologies are the {bold H}-chains, the {bold R}-chain, the {bold P}-chain, and the directional {open_quotes} arrowhead{close_quotes} chains denoted by {bold U} and {bold D}. The {bold H}-chain is found only in the sheet anion topology of {alpha}-UO{sub 2}(OH){sub 2} and consists of hexagonal sites sharing opposing edges. In {alpha}-UO{sub 2}(OH){sub 2}, all hexagons are populated with uranyl ions. The {open_quotes} arrowhead{close_quotes} chain is composed of pentagonal sites populated with uranyl ions and sharing edges and alternating with vacant triangular sites. Arrowhead chains are present in the sheet anion topologies of all other UOH sheets. Arrowhead chains are directional and can occur in both {bold U} and {bold D} {open_quotes} senses{close_quotes} within a single anion topology. The {bold P}-chain consists of edge-sharing pentagonal sites populated with uranyl ions forming a zigzag chain. The {bold P}-chain is flanked on both sides by arrowhead chains of the same {open_quotes} sense{close_quotes}. The remaining structural unit is a discontinuous {open_quotes} chain{close_quotes} of rhombic sites. This {open_quotes}{bold R}-chain{close_quotes} is produced when nested; adjacent {bold U} and {bold D} {open_quotes} arrowhead{close_quotes} chains are translated diagonally. (Abstract Truncated)

• OSTI ID: 459835
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 12 Vol. 11; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANIONS
CATIONS
CRYSTAL STRUCTURE
HYDRATES
RADIOACTIVE WASTES
TOPOLOGY
URANIUM OXIDES