Crystal structures of some niobium and tantalum oxides. IX. K/sub 3/Nb/sub 7/O/sub 19/: a new potassium niobium oxide tunnel structure
K/sub 3/Nb/sub 7/O/sub 19/ crystallizes in the triclinic system with unit cell dimensions (from single-crystal data) a = 14.143(3), b = 9.948(2), c = 6.463(2) A, ..cap alpha.. = 106.45(2), ..beta.. = 95.82(1), ..gamma.. = 97.29(1)/sup 0/, and space group P/sup 1/, z = 2. The structure was solved using the Patterson (P1 method) and Fourier techniques. Of the 4974 unique reflections measured by counter techniques 2722 with I greater than or equal to 3sigma(I) were used in the least-squares refinement of the model to a conventional R of 0.049 (R/sub w/ 0.054). The structure of K/sub 3/Nb/sub 7/O/sub 19/ may be described as consisting of edge-shared pairs of octahedra that are corner shared to one another to form double strings seven pairs long. Each of these strings is corner shared to four other identical strings forming tunnels bounded by six octahedra. Two pairs of octahedra at each end of the strings of seven pairs are edge shared to adjacent strings forming a second series of tunnels approximately perpendicular to the first series. Potassium ions are located within both series of tunnels. The structure may also be described as one in which the oxygen ions are in approximately cubic close-packed layers perpendicular to (501) with potassium ions occupying anion sites in a regular manner. 12 references, 5 figures, 2 tables.
- Research Organization:
- Monash Univ., Clayton, Australia
- OSTI ID:
- 5979608
- Journal Information:
- J. Solid State Chem.; (United States), Vol. 61:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NIOBIUM OXIDES
CRYSTAL STRUCTURE
POTASSIUM COMPLEXES
CRYSTALLOGRAPHY
EXPERIMENTAL DATA
LATTICE PARAMETERS
MILLER INDICES
MONOCRYSTALS
SPACE GROUPS
TRICLINIC LATTICES
X-RAY DIFFRACTION
ALKALI METAL COMPLEXES
CHALCOGENIDES
COHERENT SCATTERING
COMPLEXES
CRYSTAL LATTICES
CRYSTALS
DATA
DIFFRACTION
INFORMATION
NIOBIUM COMPOUNDS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies