Surface Energies and Thermodynamic Phase Stability in Nanocrystalline Aluminas

Autor:	J. M. McHale, A. Auroux, Alexandra Navrotsky, A. J. Perrotta
Rok vydání:	1997
Předmět:	Isothermal microcalorimetry Thermogravimetric analysis Molecular dynamics Multidisciplinary Adsorption Chemistry engineering Thermodynamics Corundum Calorimetry engineering.material Nanocrystalline material Surface energy
Zdroj:	Science. 277:788-791
ISSN:	1095-9203 0036-8075
DOI:	10.1126/science.277.5327.788
Popis:	Corundum, α-Al 2 O 3 , is the thermodynamically stable phase of coarsely crystalline aluminum oxide, but syntheses of nanocrystalline Al 2 O 3 usually result in γ-Al 2 O 3 . Adsorption microcalorimetry, thermogravimetric analyses, and Brunauer-Emmett-Teller adsorption experiments, coupled with recently reported high-temperature solution calorimetry data, prove that γ-Al 2 O 3 has a lower surface energy than α-Al 2 O 3 and becomes energetically stable at surface areas greater than 125 square meters per gram and thermodynamically stable at even smaller surface areas (for example, 75 square meters per gram at 800 kelvin). The results are in agreement with recent molecular dynamics simulations and provide conclusive experimental evidence that differences in surface energy can favor the formation of a particular polymorph.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::ff0db7e9ccf0dfb5aba05eae9cb1f2d3 https://doi.org/10.1126/science.277.5327.788 Zobrazit plný text záznamu