The Nanocrystalline SnO2-TiO2 System Part II: Surface Energies and Thermodynamic Stability

Joice Miagava, Andre L. Da Silva, Alexandra Navrotsky, Ricardo H.R. Castro, Douglas Gouvêa

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The thermodynamic stability of nanocrystalline SnO2-TiO2 solid solutions was studied experimentally. Microcalorimetry of water adsorption revealed a systematic decrease in the surface energy with increasing Ti4+ content in the SnO2-rich compositions, consistent with previous reports of Ti4+ segregation on the surface. The surface energy change was accompanied by an increase in the magnitude of the heat of water adsorption, also indicating a modification of the SnO2 surface by Ti4+. Supporting the water adsorption data, calculations using high-temperature oxide melt solution calorimetry data also suggest a decrease in the interface energies. A thermodynamic analysis showed that the observed surface energy decrease is responsible for an increase in the stability of solid solutions in the nanophase regime. Although a miscibility gap is expected in this system from bulk phase diagrams, the surface energy contribution modifies the bulk trend and promotes extensive solid solutions when the surface area is above a critical value dependent on the surface energy and the bulk enthalpy of mixing.

Original languageEnglish (US)
Pages (from-to)638-644
Number of pages7
JournalJournal of the American Ceramic Society
Volume99
Issue number2
DOIs
StatePublished - Feb 1 2016
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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