Thermochemistry of Si6-zAlzOzN8-z (z = 0 to 3.6) materials

Jian Jie Liang, Alexandra Navrotsky, Valerie J. Leppert, Michael J. Paskowitz, Subhash H. Risbud, Thomas Ludwig, Hans J. Seifert, Fritz Aldinger, Mamoru Mitomo

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Enthalpies of formation were determined for β-sialon phases (Si6-zAlzOzN8-z, z = 0.46 to 3.6) by high-temperature oxidative drop solution calorimetry using an alkali-metal borate (52 wt% LiBo2; 48 wt% NaBO2) solvent. Oxygen gas was bubbled through the melt to accelerate oxidation of the oxynitride samples during dissolution. Sialons near z = 2 appear less stable energetically than ones with higher or lower nitrogen content. A large configurational entropy contribution for sialons with z>2 may further stabilize these materials. This larger free energy driving form may be the reason for success in pulse-activated processing of these materials. The enthalpies of formation further suggest that a greater driving form for oxynitride formation exists in batch synthesis using SiO2 rather than Al2O3.

Original languageEnglish (US)
Pages (from-to)4630-4636
Number of pages7
JournalJournal of Materials Research
Volume14
Issue number12
DOIs
StatePublished - Dec 1999
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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