Constraint of oxygen fugacity during field-assisted sintering: TiO 2 as a test case

Dat V. Quach, Andrey A. Levchenko, Alexandra Navrotsky, Joanna R. Groza

Research output: Contribution to journalArticlepeer-review

Abstract

Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO2 as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite-CO-O2 equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10-16 atm, which is higher than the value obtained from thermodynamic equilibrium of graphite-CO-O2 at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase.

Original languageEnglish (US)
Pages (from-to)970-974
Number of pages5
JournalJournal of the American Ceramic Society
Volume91
Issue number3
DOIs
StatePublished - Mar 2008
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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