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

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 determinati...

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Published inJournal of the American Ceramic Society Vol. 102; no. 8; pp. 4848 - 4861
Main Authors McCormack, Scott J., Tseng, Kuo‐Pin, Weber, Richard J. K., Kapush, Denys, Ushakov, Sergey V., Navrotsky, Alexandra, Kriven, Waltraud M.
Format Journal Article
LanguageEnglish
Published Columbus Wiley Subscription Services, Inc 01.08.2019
Subjects
Carbon dioxide
Carbon dioxide lasers
Conical nozzles
Hafnium oxide
Liquidus
Molar volume
Phase diagrams
Phase rule
Quadrupoles
Solidus
Tantalum
Tantalum oxides
Temperature
Transformation temperature
X-ray diffraction
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Summary: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. HfO2–Ta2O5‐Temperature phase space built based on the observed equilibrium phases from in situ X‐ray powder diffraction and the Gibbs Phase Rule.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.16271