Thermodynamics of formation for zirconolite (CaZrTi2O7) from T = 298.15 K to T = 1500 K

Robert L. Putnam, Alexandra Navrotsky, Brian F. Woodfield, Juliana Boerio-Goates, Jennifer L. Shapiro

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Zirconolite (CaZrTi2O7) has been proposed as a ceramic host for the long-term disposal of excess weapons-grade plutonium. Using high-temperature oxide-melt solution calorimetry, the standard molar enthalpy of formation at T = 298.15 K for zirconolite, ΔfHom = -(3713.7 ± 4.5) kJ·mol-1, has been obtained. In combination with the third-law entropy Δ298.15 K0 Som obtained by using adiabatic calorimetry on the same sample, the standard molar Gibbs free energy of formation at T = 298.15 K, ΔfGom = -(3514.5 ± 4.5) kJ·mol-1, has also been obtained. The formation enthalpies, free energies, and third-law entropies ΔT0 Sm are reported from T = 298.15 K to T = 1500 K. Also reported for ZrTiO4, a compound of interest with respect to the (CaO, TiO2, ZrO2) phase diagram containing zirconolite, are the first estimates of the standard molar enthalpy and Gibbs free energy of formation, ΔfHom(ZrTiO4) = -(2048.7 ± 5.0) kJ·mol-1, and ΔfGom(ZrTiO4) = -(1935.7 ± 5.0) kJ·mol-1.

Original languageEnglish (US)
Pages (from-to)229-243
Number of pages15
JournalJournal of Chemical Thermodynamics
Volume31
Issue number2
DOIs
StatePublished - Feb 1999
Externally publishedYes

Keywords

  • Calorimetry
  • Enthalpy of formation
  • Nuclear waste
  • Plutonium disposition
  • Thermodynamic properties
  • Zirconolite (CaZrTiO)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Physical and Theoretical Chemistry

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