In-situ determination of the HfO2–Ta2O5-temperature phase diagram up to 3000°C

Scott J. McCormack, Kuo Pin Tseng, Richard J.K. Weber, Denys Kapush, Sergey V. Ushakov, Alexandra Navrotsky, Waltraud M. Kriven

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The previously unknown experimental HfO2–Ta2O5-temperature phase diagram has been elucidated up to 3000°C using a quadrupole lamp furnace and conical nozzle levitator system equipped with a CO2 laser, in conjunction with synchrotron X-ray diffraction. These in-situ techniques allowed the determination of the following: (a) liquidus, solidus, and invariant transformation temperatures as a function of composition from thermal arrest experiments, (b) determination of equilibrium phases through testing of reversibility via in-situ X-ray diffraction, and (c) molar volume measurements as a function of temperature for equilibrium phases. From these, an experimental HfO2–Ta2O5-temperature phase diagram has been constructed which is consistent with the Gibbs Phase Rule.

Original languageEnglish (US)
Pages (from-to)4848-4861
Number of pages14
JournalJournal of the American Ceramic Society
Issue number8
StatePublished - Aug 2019
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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