Thermodynamics of formation for zirconolite (CaZrTi2O7) fromT=298.15 K toT=1500 K

The thermodynamics of formation, molar heat capacity, and thermodynamic functions ofZrTiO4(cr)

“…The resulting diffraction pattern was in good agreement with that reported for ZrTiO 4 (JCPDS file # 34-0415). No peaks associated with the starting materials were evident.…”

“…(1,2) Among the phases found in these ceramics is zirconolite (CaZrTi 2 O 7 ). (3)(4)(5) Important to the development, performance modeling, and optimization of a nuclear waste host is an understanding of the formation energetics of the phases that comprise the waste material. (4,6,7) We have undertaken an experimental investigation of ZrTiO 4 , which is a neighboring phase to CaZrTi 2 O 7 in the (CaO, TiO 2 , ZrO 2 ) system, and for which no thermodynamic data have been reported.…”

“…(3)(4)(5) Important to the development, performance modeling, and optimization of a nuclear waste host is an understanding of the formation energetics of the phases that comprise the waste material. (4,6,7) We have undertaken an experimental investigation of ZrTiO 4 , which is a neighboring phase to CaZrTi 2 O 7 in the (CaO, TiO 2 , ZrO 2 ) system, and for which no thermodynamic data have been reported. McHale and Roth (8) have proposed ZrTi 2 O 6 as the stable phase in the (ZrO 2 , TiO 2 ) system at ambient pressure and temperatures below T = 1300 K. In addition, ZrTiO 4 is also used widely in the electronics industry, so information about the relative thermodynamic stability of this material should prove useful.…”

“…Values for the standard molar Gibbs energies and enthalpies of formation of ZrTiO 4, f G o m and f H o m , and for the free energies and enthalpies for the reaction to form ZrTiO 4 (cr) from ZrO 2 (cr) and TiO 2 (cr), are tabulated over the temperature interval, 0 (T /K ) 1800. From these results, we conclude that ZrTiO 4 is not stable with respect to (ZrO 2 + TiO 2 ) at T = 298.15 K, but becomes so at T = (1250 ± 150) K. c 2001 Academic Press KEYWORDS: ZrTiO 4 ; heat capacity; entropy; enthalpy of formation; thermodynamics; enthalpy a To whom correspondence should be addressed (E-mail: jboerio-goates@byu.edu). b Current address: Los Alamos National Laboratory, NMT-11; MS-K762; Los Alamos, NM 87545, U.S.A.…”

Molar heat capacity and thermodynamic functions of zirconolite CaZrTi2O7

“…The electron microprobe analysis also showed there to be 8.24 · 10 −2 mol of ZrO 2 per mol of CaZrTi 2 O 7 . (12) The sample mass used in the calorimetric measurements was 15.9640 g; after correcting for the ZrO 2 inclusions, the resulting mass of CaZrTi 2 O 7 was 15.4998 g and the mass of ZrO 2 was 0.4642 g.…”