Crystal structure of lithium molybdenum purple bronze Li 0.9Mo 6O 17
Abstract
The crystal structure of the molybdenum ternary oxide Li 0.9Mo 6O 17 is determined by single-crystal X-ray diffraction. The crystal is monoclinic with space group {P2 1}/{m} and the lattice constants are a = 12.762(2) Å, b = 5.523(1) Å, c = 9.499(1) Å, β = 90.61(1)°, Z = 2. Full-matrix least-squares refinement gives the final values of R( F) = 0.033 and Rw( F) = 0.066 for 3019 independent reflections. The unit cell contains six crystallographically independent molybdenum sites. One-third of the molybdenum atoms are located in oxygen tetrahedra, while the others are within oxygen octahedra. The structure is built up of slabs of the MoO 6 octahedra. Each slab consists of three layers of distorted ReO 3-type MoO 6 octahedra sharing corners. The structure is rather different from that of K 0.9Mo 6O 17, although the layered feature is still preserved. The lithium ions are located in the large vacant sites between the slabs. By the application of Zachariasen's bond length-bond strength relation to the observed MoO bonds, most of the conduction electrons are found to be located in the Mo(1) and Mo(4) octahedral sites which are associated in pairs to form the Mo(1)O(11)Mo(4)O(11) double zigzag chains extending along the b-axis. Therefore the structural properties are considered to lead to the highly anisotropic electronic transport.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- January 1987
- DOI:
- 10.1016/0022-4596(87)90231-3
- Bibcode:
- 1987JSSCh..66..163O