Hydrothermal synthesis of brookite-type titanium dioxide with snowflake-like nanostructures using a water-soluble citratoperoxotitanate complex

Makoto Kobayashi, Valery Petrykin, Koji Tomita, Masato Kakihana

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Hydrothermal synthesis of brookite-type titanium dioxide was performed with excellent reproducibility using an aqueous NH3 solution of a water-soluble citratoperoxotitanate (CPT) complex. X-ray diffraction confirmed that the brookite phase was formed by hydrothermal treatment of the CPT complex in NH3 solution with a concentration of more than 6.5 wt%, whereas single phase anatase was obtained when distilled water without any additives was applied as the solvent. The aspect ratios of the obtained rod-like brookite particles increased from 5 up to 20 with an increase of the NH3 concentration. Transmission electron microscopy and selected area electron diffraction measurements provided evidence that the growth of the brookite particles is along the c-axis. Hydrothermal treatment of the CPT complex at high NH3 concentrations resulted in the formation of agglomerated brookite particles with unusual shapes, where many rod-like particles were branched around a somewhat longer central particle, and the side view of the agglomerated particles revealed two-dimensional crystal growth within a given restricted plane. The multi-needle agglomerate of particles was snowflake shaped. The reason for the formation of brookite with this unique morphology may be attributed to an intrinsic character of the CPT complex itself, although the mechanism is yet to be clarified.

Original languageEnglish
Pages (from-to)30-37
Number of pages8
JournalJournal of Crystal Growth
Volume337
Issue number1
DOIs
Publication statusPublished - 2011 Dec 15

Keywords

  • A1. Crystal morphology
  • A1. Nanostructures
  • A2. Growth from solutions
  • A2. Hydrothermal crystal growth
  • B1. Nanomaterials
  • B1. Titanium compounds

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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