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Author Oka, Yoshio ♦ Yao, Takeshi ♦ Yamamoto, Naoichi ♦ Sato, Shoichi
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ CRYSTAL STRUCTURE ♦ HYDROTHERMAL SYNTHESIS ♦ BARIUM OXIDES ♦ VANADIUM OXIDES ♦ MONOCRYSTALS ♦ LATTICE PARAMETERS ♦ X-RAY DIFFRACTION ♦ BOND ANGLE ♦ BOND LENGTHS ♦ EXPERIMENTAL DATA
Abstract Ba analogues of hewettite (CaV{sub 6}O{sub 16}{center_dot}9H{sub 2}O) were synthesized by the hydrothermal methods. The compounds exhibit two phases formulated by BaV{sub 6}O{sub 16}{center_dot}nH{sub 2}O and Ba{sub 1+x}V{sub 6}O{sub 16}{center_dot}nH{sub 2}O (x {approx} 0.2, n {approx} 3), and the structure of BaV{sub 6}O{sub 16}{center_dot}nH{sub 2}O has been determined from a single crystal study. It crystallizes in the orthorhombic system Pnmm with a = 12.162(3) {angstrom}, b = 10.841(4) {angstrom}, c = 17.035(4) {angstrom}, and Z = 6 and the structure refinements led to R = 0.066 and R{sub w} = 0.076 for 1,480 reflections with I > 3{sigma}(I). The structure is basically analogous to that of {gamma}-Li{sub 1+x}V{sub 3}O{sub 8} or CaV{sub 6}O{sub 16}{center_dot}9H{sub 2}O, consisting of V{sub 6}O{sub 16} layers and interstitial hydrated Ba atoms. The V{sub 6}O{sub 16} layers stack along the c axis with 8.518-{angstrom} spacing which is half of the c axis; adjacent layers are mirror images of each other. Ba atoms reside in three kinds of sites with totally different oxygen coordinations. Their interlayer distributions result in another long period along the b axis which is triple the ordinary 3.6-{angstrom} period of the hewettite compounds. This is the first single-crystal structural study of the synthetic hewettite compounds.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 1998-11-01
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 140
Issue Number 2


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