Spinodal decomposition in the TiO2-VO2 system

Zenji Hiroi, Hiroaki Hayamizu, Toru Yoshida, Yuji Muraoka, Yoshihiko Okamoto, Jun Ichi Yamaura, Yutaka Ueda

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


Spinodal decomposition is a ubiquitous phenomenon leading to phase separation from a uniform solution. We show that a spinodal decomposition occurs in a unique combination of two rutile compounds of TiO2 and VO 2, 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. The spinodal decomposition takes place below 830 K at a critical composition of 34 mol % Ti, 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, which is probably due to a large misfit strain induced by lattice matching at the coherent interface.

Original languageEnglish
Pages (from-to)2202-2210
Number of pages9
JournalChemistry of Materials
Issue number11
Publication statusPublished - Jun 11 2013


  • TiO
  • VO
  • metal-insulator transition
  • phase separation
  • rutile structure
  • spinodal decomposition

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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