Preparation and crystal structure of a new lithium bismuth oxide: LiBiO3

A new lithium bismuth oxide was discovered during the investigation of low-temperature hydrothermal reactions of the hydrated sodium bismuth oxide, NaBiO3 . nH(2)O. This lithium bismuth oxide crystallizes in the orthorhombic system with the lattice parameters a = 8.8278(3), b = 4.9135(2), and c = 10.6914(3) Angstrom, space group Pccn, and Z = 8. The crystal structure was refined using neutron powder diffraction data giving final R factors of R(WP) = 10.04, R(P) = 7.64, R(E) = 3.88, and R(I) = 4.86%. The LiBiO3 crystal structure is similar to that of LiSbO3. Both structures can be considered as based on an array of hexagonally closed packed oxygen atoms with cations occupying two-thirds of the octahedral sites. In both structures, the LiO6 octahedra share faces to form a continuous string. However, in the LiSbO3 structure SbO6 octahedra each share two edges forming a continuous zigzag chain whereas in the LiBiO3 structure BiO6 octahedra each share one edge only. Thus, the LiBiO3 structure also resembles the cubic KBiO3 structure, both structures being based on a dimer unit of the type Bi2O10 which shares corners forming a network having interstitial alkali cations. On heating to about 300 degrees C, LiBiO3 transforms to LiBiO2 through evolution of oxygen and reduction of Bi5+ to Bi3+. (C) 1996 Academic Press, Inc.