INOR 391 |
| Stoichiometric VO2 exhibits a large reversible change of electric, magnetic and optical properties at around 340 K. This metal-to-insulator transition is accompanied by a structural transition from a rutile to a monoclinic phase. We present a new phase of nonstoichiometric VO2 synthesized by a nonaqueous sol-gel route starting from VOCl3 and benzyl alcohol as a reaction medium. The powder consists of isolated single-crystalline nanorods grown along the [010] direction of tetragonal V7.2O16*4.2H2O with the lattice parameters a = 10.427(2) Å, c = 3.009(1) Å, and space group I4/m (87). Each V cation is coordinated with 6 oxygen atoms forming highly distorted octahedra. The structure possesses channels of about 5 Å in diameter along the c-axis that are large enough for the inclusion of crystal water. Ab initio electron density functional theory calculations revealed that V7.2O16*4.2H2O has a narrow energy gap of 1.16 eV. |
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Synthesis and Characterization of Materials
1:30 PM-5:30 PM, Monday, August 20, 2007 BCEC -- 206 A/B, Oral
Division of Inorganic Chemistry |