| Title | Preparation and Crystal Structures of Bismuth Technetates: A New Metal Oxide System. | | Author(s) | Rodriguez EE, Poineau F, Llobet A, Czerwinski K, Seshadri R, Cheetham AK | | Institution | Manuel Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, Materials Research Laboratory, University of California, Santa Barbara, California 93106, Harry Reid Center for Environmental Studies, University of Nevada, Las Vegas, Nevada 89154-4009, and Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, U.K. akc30@cam.ac.uk. | | Source | Inorg Chem 2008 Jun 24. | | Abstract | Two new oxides have been unambiguously identified as Bi 2Tc 2O 7-delta with delta = 0.14(1) and Bi 3TcO 8 through X-ray absorption near-edge structure spectroscopy and neutron powder diffraction. The compound Bi 2Tc 2O 7-delta has a cubic pyrochlore-type structure with a = 10.4746(1) A, space group F d3 m (origin choice 2), and Z = 8. The compound Bi 3TcO 8 is also cubic, a = 11.5749(1) A, space group P2 13, Z = 8, and has a fluorite-related crystal structure. In Bi 2Tc 2O 7-delta the Tc(IV) cations are octahedrally coordinated, whereas in Bi 3TcO 8 the Tc(VII) cations are tetrahedrally coordinated. A third new phase, probably Bi 3Tc 3O 11, could not be obtained pure, but preliminary X-ray powder diffraction data affords a primitive cubic lattice with a = 9.3433(1) A. On the basis of structural similarities between Bi 2Tc 2O 7-delta and closely related oxides, Bi 2Tc 2O 7-delta is expected to be a metallic oxide with Pauli paramagnetism. Electronic structure calculations of both Bi 2Tc 2O 7-delta and Bi 3TcO 8 further support metallic conductivity in the former and insulating behavior in the latter. The inert pair effect of the Bi cations on the crystal structures of Bi 2Tc 2O 7-delta and Bi 3TcO 8 is also described. In addition, calculations of the valence electron localization function for Bi 2Tc 2O 7-delta and Bi 3TcO 8 provide further visualization of the Bi 6s (2) lone pair electrons in the real space of the crystal structures. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 18572909 |
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