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2653697 
Journal Article 
Synthesis and Phase Stability of Metastable Bixbyite V2O3 Colloidal Nanocrystals 
Bergerud, Amy; Buonsanti, R; Jordan-Sweet, JL; Milliron, DJ 
2013 
Yes 
Chemistry of Materials
ISSN: 0897-4756
EISSN: 1520-5002 
25 
15 
3172-3179 
WOS:000323193000033 
We have recently developed a colloidal route to vanadium sesquioxide (V2O3) nanocrystals with a metastable bixbyite crystal structure. In addition to being one of the first reported observations of the bixbyite phase in V2O3, it is also one of the first successful colloidal syntheses of any of the vanadium oxides. The nanocrystals, measuring 5 to 30 nm in diameter, possess a flower-like morphology which densify into a more spherical shape as the reaction temperature is increased. The bixbyite structure was examined by X-ray diffraction and an aminolysis reaction pathway was determined by Fourier transform infrared spectroscopy. A direct band gap of 1.29 eV was calculated from optical data. Under ambient conditions, the structure was found to expand and become less distorted, as evidenced by XRD. This is thought to be due to the filling of structural oxygen vacancies in the bixbyite lattice. The onset of the irreversible transformation to the thermodynamically stable rhombohedral phase of V2O3 occurred just under 500 degrees C in an inert atmosphere, accompanied by slight particle coarsening. A critical size of transformation between 27 and 42 rim was estimated by applying the Scherrer formula to analyze XRD peak widths during the course of the transformation. The slow kinetics of transformation and large critical size reveal the remarkable stability of the bixbyite phase over the rhombohedral phase in our nanocrystal system. 
vanadium oxide; phase transformation; oxidation; aminolysis; nanoflowers; surface energy