Thermochemistry of stoichiometric rare earth oxyfluorides REOF

Shuhao Yang, Andre Anderko, Richard E. Riman, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Rare earth oxyfluorides (REOF) have potential applications in luminescent devices and energy storage and are important for synthesis and properties of RE-doped oxyfluoride glasses. This study evaluates the thermodynamic properties of stoichiometric REOF with varying RE (RE = La, Nd, Gd, Ho, Y, and Yb) elements using high temperature oxide melt solution calorimetry and investigates the phase transitions of YbOF by differential scanning calorimetry. The formation enthalpies from binary oxides and fluorides are exothermic and become less exothermic with the decrease of ionic radius of RE3+, showing that REOF compounds are energetically stable relative to equal molar mixtures of RE2O3 and REF3 and the RE–O interactions contribute to most of their thermodynamic stabilities. Different from REOF with large RE ions (La–Er and Y) having the rhombohedral phase, REOF with small cations (e.g., Yb) possesses the monoclinic structure as the more energetically stable phase at room temperature. However, the slow transition between the monoclinic and cubic phases easily generates the rhombohedral phase, which is favored by kinetics.

Original languageEnglish (US)
Pages (from-to)1472-1480
Number of pages9
JournalJournal of the American Ceramic Society
Issue number2
StatePublished - Feb 2022


  • fluorine/fluorine compounds
  • phase transition
  • rare earths
  • thermal analysis
  • thermodynamics

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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