作者:N. M. Laptash、E. B. Merkulov、I. G. Maslennikova
DOI:10.1023/a:1010105024143
日期:——
The thermal behaviour of ammonium oxofluorotitanates (NH4)(3)TiOF5, (NH4)(2)TiOF4 and NH4TiOF3 was investigated by thermoanalytical, X-ray and IR spectroscopic methods. The first decomposition stages under quasi-isobaric conditions are characterized by the formation of (NH4)(2)TiF6 and ammonium oxofluorotitanate with the less content of ammonium and fluorine than in the initial compound. The decomposition process is accompanied by the Ti(IV) reducing due to ammonia evolved. The new ammonium oxofluorotitanate of high volatility was isolated and characterized. Ammonium-containing non-stoichiometric titanium oxyfluorides are the final products of thermal decomposition of ammonium oxofluorotitanates.
A Facile Synthesis of Uniform NH<sub>4</sub>TiOF<sub>3</sub> Mesocrystals and Their Conversion to TiO<sub>2</sub> Mesocrystals
作者:Lei Zhou、David Smyth-Boyle、Paul O'Brien
DOI:10.1021/ja076187c
日期:2008.1.30
Uniform mesocrystals of TiO2 (anatase) have been prepared from mesocrystals of NH4TiOF3NH4TiOF3 was synthesized from an aqueous solution containing (NH4)(2)TiF6 and H3BO3 in the presence of a nonionic surfactant Brij 56, Brij 58, or Brij 700, at low temperatures. The exterior shapes of NH4TiOF3 mesocrystals can be tuned by adjusting the reagent concentration, reaction time, reaction temperature, and rate of stirring. The formation of the NH4TiOF3 mesocrystals proceeds via a self-assembly process involving nonclassical crystal growth. By sintering in air at 450 degrees C, or washing with H3BO3 solution at ambient temperatures, the NH4TiOF3 mesocrystals can be converted to mesocrystals of TiO2 (anatase), and the original architecture is retained.