Rapid Hydrothermal Preparation of Rutile TiO2 Nanoparticles by Simultaneous Transformation of Primary Brookite and Anatase: An in Situ Synchrotron PXRD Study

详细信息    查看全文

• 作者：Jian-Li Mi ; Casper Clausen ; Martin Bremholm ; Nina Lock ; Kirsten M. 脴. Jensen ; Mogens Christensen ; Bo B. Iversen
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：December 5, 2012
• 年：2012
• 卷：12
• 期：12
• 页码：6092-6097
• 全文大小：413K
• 年卷期：v.12,no.12(December 5, 2012)
• ISSN：1528-7505

文摘

The formation mechanism and crystal growth of TiO₂ in high-temperature high-pressure fluids were studied using HCl or H₂SO₄ as additives. In situ synchrotron radiation powder X-ray diffraction reveals that phase-pure rutile TiO₂ nanoparticles can be formed using HCl as additive, whereas phase-pure anatase TiO₂ is obtained when H₂SO₄ is used as additive. The supercritical (or near-critical) conditions provide a fast, one-step synthesis of rutile TiO₂ nanoparticles and when using a 1:1 volume ratio of isopropanol鈥搘ater as solvent at a temperature of 300 掳C and a pressure of 25 MPa particles with an average particle size of about 22 nm are obtained in 20 min. A detailed analysis by sequential Rietveld refinements shows that the formation of rutile TiO₂ occurs by a combined transformation of anatase and brookite TiO₂. Analysis of the unit cell dimensions of the nanoparticles shows a lattice expansion with decreasing particle size for anatase prepared with H₂SO₄ medium and this may explain the stability of anatase particles that are significantly larger than their critical size.