The apatite structure without an inversion center in a new bismuth calcium vanadium oxide: BiCa[sub 4]V[sub 3]O[sub 13]

Journal Article · Sat May 01 04:00:00 EDT 1993 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1006/jssc.1993.1140· OSTI ID:6187604

Huang, Jinfan; Sleight, A W ^[1]

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1. Oregon State Univ., Corvallis (United States)

A new bismuth calcium vanadium oxide, BiCa[sub 4]V[sub 3]O[sub 13], with hexagonal symmetry has been synthesized: space group P6[sub 3] (No. 173), a = 9.819(2) [Angstrom], c = 7.033(2) [Angstrom], V = 587.2(3) [Angstrom][sup 3], and Z = 2. The structure was solved and refined from single crystal X-ray data leading to R = 0.055 and R[sub w] = 0.069 for 1076 unique reflections. Three different types of Ca sites were found: Ca(1) and Ca(2) coordinate to six O atoms, and Ca(3) coordinates to nine O atoms. There is no Bi site; instead, Bi partially occupies the Ca(1) and Ca(2) sites. The V atom is coordinated to four O atoms and forms a distorted tetrahedron with the V-O bond lengths ranging from 1.693(6) [Angstrom] to 1.72(1) [Angstrom] and O-V-O angles varying from 102.5(7)[degrees] to 114.7(6)[degrees]. The coordination polyhedra of Ca(1) and Ca(3) share faces forming chains along the c axis, and the coordination hexahedra of Ca(2) also form a chain along the c axis through sharing the corners among themselves. The VO[sub 4] tetrahedra connect the two types of chains forming a three dimensional structure. The BiCa[sub 4]V[sub 3]O[sub 13] formula may be written as A[sub 5](VO[sub 4])[sub 3]O to emphasize that this structure is essentially the same as the apatite structure, except that the inversion center is missing. Many compounds previously reported to have the apatite structure may actually have the lower symmetry version of this structure found in this study and thus be candidates for ferroelectricity. 15 refs., 4 figs., 4 tabs.

• OSTI ID: 6187604
• Journal Information: Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 104:1; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
BISMUTH OXIDES
BOND ANGLE
BOND LENGTHS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
DIMENSIONS
HEXAGONAL LATTICES
LATTICE PARAMETERS
LENGTH
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SYMMETRY
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES
X-RAY DIFFRACTION