N. Kumada

The infrared spectra of the two polymorphic forms of WOPO4

The infrared spectra of the two polymorphic forms of WOPO{sub 4} were recorded and assigned by comparison with those of related materials. The results confirm the suspected relation of the high pressure form to that of the tetragonal {alpha}-MOPO{sub 4} (M = Nb, Ta, V, Mo) compounds and of the low pressure form with the monoclinic {beta}-NbOPO{sub 4} and {beta}-TaOPO{sub 4}.

Hydrothermal synthesis and crystal structure analysis of two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79

Abstract Two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79, were prepared by hydrothermal reaction using NaBiO3·nH2O as one of the starting compounds. The crystal structures of these compounds were refined by using synchrotron X-ray powder diffraction data. The former bismuthate has a MnSb2O6-type structure with a hexagonal cell (space group: P321); the cell parameters were a = 9.3641(7) and c = 4.9523(3) Å, and the final R-factors were Rwp = 4.59% and Rp = 3.04%. The latter bismuthate has a fluorite-type structure with a cubic cell (space group: ) of a = 5.4110(4) Å, and the final R-factors were Rwp = 4.79% and Rp = 3.57%. These new bismuthates exhibit no photocatalytic activity under visible light.

Preparation of α-Fe2O3 particles with controlled shape and size via a facile hydrothermal route

α-Fe2O3 particles with controlled shape and size have been prepared by a facile hydrothermal reaction between ferric chloride hexahydrate (FeCl36H2O) and sodium hydroxide (NaOH) at 160°C. X-ray powder diffraction pattern indicates that the product is single-phase of α-Fe2O3.The morphology of α-Fe2O3 particles changed as homogenous sphere, top-shape and cube, depending on solution pH. Meanwhile, monodispersed cube particles of α-Fe2O3 are also prepared under the same conditions using surfactant of hexadecyl trimethyl ammonium bromide (CTAB). The experimental results suggest that particle size can be controlled by adjusting the solution pH and amount of CTAB.