Redetermination of the structure of Bi2MoO6, koechlinite

Abstract

The crystal structure of koechlinite has been redetermined by single-crystal X-ray analysis. The space group is Pea21, with cell dimensions: a = 5.487 (2); b = 16.226 (6); e = 5.506 (2) A,. There are four molecular units per unit cell. The structure was refined with block-matrix least-squares methods. The final R on F value was 8.7 % for 788 independent reflexions, including the unobserved reflexions. Molybdenum is octahedrally surrounded by six oxygen ions. These octahedra share four corners with neighbouring octahedra in one plane. The other two apex ions points towards a BiO layer of the type that occurs, for example, in BiOC1.

High-Temperature Incommensurate-to-Commensurate Phase Transition in the Bi2MoO6 Catalyst

“…In both +Bi O ,> layers there are two short and two intermediate length bonds to the midline oxygens (i.e., O [3] for Bi [1] and O [2] for Bi [2]). Each Bi site also has two intermediate length bonds to the &&apical'' oxygens (i.e., O [6] for Bi [1] and O [1] for Bi [2]).…”

“…, with x, n"1 and M"Mo (7). These consist of a strongly distorted nearly square layered network of Mo polyhedra separated by +Bi O ,> layers.…”

“…Our attention in this paper will be on the thermal evolution of the (L) and (I) forms. ,> layer being connected along b to the adjacent +MoO ,\ layers by oxygen O [1] and the other +Bi [1] O [3] ,> layer connecting via O [6] to the neighboring +MoO ,\ layers. The molybdenum has highly distorted octahedral coordination with four equatorial oxygen sites involving pairs of O [4] and O [5] and two apical oxygens (O [1] and O [6]).…”

The crystal structure of russellite; a re-determination using neutron powder diffraction of synthetic Bi2WO6

“…Starting atomic parameters were those of koechlinite derived from the single crystal analysis of Van Den Elzen and Rieck (1973). Convergence from these trial coordinates was rapid and excellent agreement was found between experimental data and calculated, with agreement factors Rp = 4.83%, Rwp = 6.36% and RE = 3.69% for data in the range 26.00 ~ -< 20 -< 84.00 ~ (for definition of agreement factors see Table 1).…”

Roles of bulk γ(L)-Bi2MoO6 and surface β-Bi2Mo2O9 in the selective catalytic oxidation of C3H6

“…The application Dispcrystal [11] was developed using the space group method. Lattice constants for the β-, γ(L)-and γ(H)-phases and the values of the x, y, and z coordinates for all atoms are provided in the attached CIF data, i.e., crystal structure data [10,14,15].…”