Particle size effects on transformation kinetics and phase stability in nanocrystalline TiO ₂

Abstract

Other| August 01, 1997 Particle size effects on transformation kinetics and phase stability in nanocrystalline TiO2 Amy A. Gribb; Amy A. Gribb University of Wisconsin-Madison, Department of Geology and Gephysics, Madison, WI, United States Search for other works by this author on: GSW Google Scholar Jillian F. Banfield Jillian F. Banfield Search for other works by this author on: GSW Google Scholar Author and Article Information Amy A. Gribb University of Wisconsin-Madison, Department of Geology and Gephysics, Madison, WI, United States Jillian F. Banfield Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online Issn: 1945-3027 Print Issn: 0003-004X Copyright © 1997 by the Mineralogical Society of America American Mineralogist (1997) 82 (7-8): 717–728. https://doi.org/10.2138/am-1997-7-809 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Amy A. Gribb, Jillian F. Banfield; Particle size effects on transformation kinetics and phase stability in nanocrystalline TiO2. American Mineralogist 1997;; 82 (7-8): 717–728. doi: https://doi.org/10.2138/am-1997-7-809 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Kinetic studies conducted primarily between 465 and 525 °C demonstrate that the rate of the polymorphic anatase to rutile transformation increases dramatically when the reacting anatase is very finely crystalline. Coarsening of the reactant anatase and product rutile crystallites occurs simultaneously with the transformation. Kinetic behavior and quantification of transformation rate as a function of average crystallite size indicate that the increase in favorable nucleation sites is a likely cause of increase in transformation rate at small crystallite sizes. Additionally, experimental evidence supports the reversal of stabilities of anatase and rutile at small crystallite sizes. It is proposed that the reversal of stabilities is the result of rutile having a higher surface energy than the anatase phase. Data for coarsening kinetics of anatase and rutile supports the prediction that the surface energy of rutile is significantly larger than that of anatase. Thermodynamic data and theoretical estimates are used to show that a 15% greater surface energy for rutile causes the total free energy of rutile to be greater (less negative) than anatase at crystallite diameters in the few nanometer range. Given the fact that anatase and rutile structures have no polymerized octahedral fragments in common, this may be significant in determining the nature of the nucleated phase. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.