resumo
Chemical potential phase stability diagrams were calculated from relevant thermodynamic properties and used to predict the thermodynamic driving force under prospective conditions of room temperature mechanosynthesis. One analysed the dependence of chemical potential diagrams on temperature and partial pressure of evolving gases such as oxygen or carbon dioxide, as expected on using strontium peroxide or strontium carbonate as precursor reactants for the alkali earth component. Thermodynamic calculations were also obtained for changes in titania precursor reactants, including thermodynamic predictions for reactivity of strontium carbonate with amorphous titania. Experimental evidence showed that strontium titanate can be obtained by mechanosynthesis of strontium carbonate+ anatase mixtures, due to previous amorphization under high energy milling. Ability to perform mechanosynthesis with less energetic milling depends on the suitable choice of alternative precursor reactants, which meet the thermodynamic requirements without previous amorphization; this was demonstrated by mechanosynthesis from anatase + strontium peroxide mixtures. (C) 2011 Elsevier Inc. All rights reserved.
palavras-chave
MECHANOCHEMICAL SYNTHESIS; MECHANICAL ACTIVATION; AB-INITIO; VARIABLE-TEMPERATURE; CALCIUM TITANATE; POWDERS; BATIO3; CATIO3; MIXTURES; ANATASE
categoria
Chemistry
autores
Monteiro, JF; Ferreira, AAL; Antunes, I; Fagg, DP; Frade, JR
nossos autores
Isabel Alexandra Gonçalves Antunes
Investigador Júnior
Jorge Ribeiro Frade
Professor(a) Jubilado(a)agradecimentos
This work received funding from the European Union's Fund for Coal and Steel (RFCS) research program under grant agreement IERO-RSF-PR-09099 and was also partially supported by the FCT, Portugal.