2019-Sustainable Industrial Processing Summit
SIPS2019 Volume 9: Tressaud Intl. Symp. / Solid State Chemistry for Applications and Sustainable Development
| Editors: | F. Kongoli, M.A. Alario Franco, J. Etourneau, S. Kalogirou, F.D.S. Marquis, R. Martins, K. Poeppelmeier, B. Raveau, Y. Shimakawa, M. Takano |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2019 |
| Pages: | 130 pages |
| ISBN: | 978-1-989820-08-7 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Spinodal Decomposition in the TiO2-VO2 system
Zenji Hiroi1;1INSTITUTE FOR SOLID STATE PHYSICS, UNIVERSITY OF TOKYO, Kashiwa, Japan;
Type of Paper: Regular
Id Paper: 184
Topic: 52
Abstract:
Spinodal decomposition is a ubiquitous phenomenon leading to phase separation from a uniform solution. We show that spinodal decomposition occurs in a unique combination of two rutile compounds of TiO2 and VO2 [1-3], which are chemically and physically distinguished from each other: TiO2 is a wide-gap insulator with photocatalytic activities, and VO2 is assumed to be a strongly correlated electron system which exhibits a dramatic metal-insulator transition at 342 K. Spinodal decomposition takes place below 830 K at a critical composition of 34 mol% Ti. It generates a unidirectional composition modulation along the c axis with a wavelength of approximately 6 nm, and finally results in the formation of self-assembled lamella structures made up of Ti-rich and V-rich layers stacked alternately with 30-50 nm wavelengths. A metal-insulator transition is not observed in quenched solid solutions with intermediate compositions, but emerges in the thin V-rich layers as the result of phase separation. Interestingly, the metal-insulator transition remains as sharp as in pure VO2 even in such thin layers and takes place at significantly reduced temperatures of 310-340 K. This is probably due to a large misfit strain induced by lattice matching at the coherent interface.
Keywords:
Important classes of materials;References:
[1] Z. Hiroi, H. Hayamizu, T. Yoshida, Y. Muraoka, Y. Okamoto, J. Yamaura, Y. Ueda, Chem. Mater. 25 (2013) 2202-2210.[2] Z. Hiroi, Prog. Solid State Chem. 43 (2015) 47-69.
[3] Z. Hiroi, T. Yoshida, J. Yamaura, Y. Okamoto, APL Mater. 3 (2015) 062508.