The crystal structure of a new niobium phosphate bronze, Nb18P2.5O50, was determined by single-crystal X-ray diffraction, and its physical properties were studied. Nb18P2.5O50 crystallizes in the tetragonal system with space group 14/m (No. 87) and Z = 1. The unit cell parameters are a = 15.593(1) Å, c = 3.8282(3) Å, and V = 930.8(1) Å3. The structural refinement by a full-matrix least-squares technique led to R = 0.055 (Rw = 0.052). The structure of Nb18P2.5O50 is built up from 3 × 3 slabs of ReO3-type NbO6 octahedra. These slabs are stacked alternatively along the crystallographic c axis and joined together by edge-sharing. In the ab plane, the slabs of NbO6 octahedra are interconnected through corner-sharing PO4 tetrahedra. Single-crystal resistivity measurement of Nb18P2.5O50 along the crystallographic c axis showed a semiconducting behavior with an activation energy of 0.13(1) eV. The magnetic susceptibility data indicate a modified Curie-Weiss behavior with the Curie-Weiss temperature θ = −3.70 K and μeff/Nb4+ = 0.8 ¼B.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry