> > You may try the COD (Crystallography Open Database) at > http://www.crystallography.net/search.html where at least I was able to > find an orthorhombic NbPO5 phase. >
The inorganic crystal structure database ICSD references the Sleight and Raveau group papers: http://www.sciencedirect.com/science/article/pii/S0022459601992278 http://www.degruyter.com/view/j/zkri.1986.177.issue-3-4/zkri.1986.177.3-4.277/zkri.1986.177.3-4.277.xml Yes the first paper's title is "orthorhombic" but uses neutron powder diffraction to study the monoclinic-orthorhombic transition, and the Raveau group use single crystals and high resolution electron microscopy. If you are trying to work on niobium oxides with ordinary x-ray powder diffraction, life will be difficult. These materials are notoriously non-stoichiometric and unstable, apart from the big difference in the scattering power of the atoms for x-rays. The HREM images illustrate the problem. Good luck ! Alan. ______________________________________________ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * <alan.he...@neutronoptics.com> +33.476.98.41.68 http://www.NeutronOptics.com/hewat ______________________________________________
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