摘要：

The crystal structure of β-BiNbO4 has been determined from three-dimensional X-ray data. The crystals are triclinic with a = 7.611 Å, b = 5.536 Å, c= 7.919 Å, α = 89.88°, β = 77.43°, γ = 87.15°, Z = 4, space group P1. Full-matrix least-squares refinement using isotropic temperature factors has reached R = 0.122 for 642 visually estimated reflections. The structure contains unusual sheets of formula [NbO4]∞ in which the NbO octahedra are joined at four vertices such that the two free ones are cis. NbO distances range from 1.80 to 2.31 Å. The bismuth atoms hold these sheets together and are coordinated to eight oxygens in the form of a very distorted square antiprism. Structurally, β-BiNbO may be considered an antiferroelectric, ferroelastic member of the BaMF4 prototype family.

展开