Synthesis and structure of new transition metal containing bismuth oxides

Exploratory synthesis is the discovery of new compounds with interesting structures and properties. The subject of this thesis is exploratory synthesis of bismuth containing oxides. Bismuth containing oxides have many interesting properties, which are ionic conductivity, ferromagnetism, superconductivity, ferroelectricity, ferroelasticity and catalytic. These properties are closely related to their specific structure which is caused by the lone electron pair effect on Bi3+, in other words, hybridization of the 6s and 6p states results in interesting stereochemistry. This can lead to some unusual and potentially useful properties.; Several new compounds BiMn2NO6 (N = P, V, As) in the BiM2NO6 family (M = divalent cation, N = pentavalent cation) have been synthesized. The structures were refined by powder X-ray and neutron diffraction data. The X-ray diffraction patterns showed these three compounds have similar structures. Like other compounds in the BiM 2NO6 family, they contain (BiO2)-infinite chains, (AO4)3- tetrahedral and interspersed M 2+ cations. Based on these same building blocks, they exhibit their own structure.; BiMnPO5 compound has been prepared and refined by powder neutron diffraction data. This material crystallizes in monoclinic symmetry. The structure can be described in terms of mixed double-chains of two edge-sharing MnO 6 octahedral alternating with two edge-sharing BiO6 octahedra. The mixed double-chains are connected to each other through the PO4 tetrahedra. During the investigation of the BiMNO5 family, BiMnVO 5 and BiMnAsO5 have also been synthesized. Their structures were determined from X-ray single crystal data. Both of them crystallized in P 1¯ space group. Bi is five fold coordinated instead of six-fold as for BiMnPO5, since the sixth oxygen-bismuth distance is over 3.20A. This point also shows some link of the comparable structures between these three new compounds.; Pyrochlore type Bi-Ta(Nb)-Mn-O new compounds were also prepared, the structures have been determined from X-ray single crystal data. They crystallized in cubic symmetry.