Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite

Details Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite

Dec 1967

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1967gecoa..31.2289h&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 31, Issue 12, pp.2289-2307

Physics

37

Scientific paper

Cryogenic heat-capacity measurements on coesite and stishovite provide thermo-dynamic properties from 5 to 350°K. The heat capacities ( C p ), entropies ( S °), and Gibbs energy functions [-( G ° - H ° 0 )/ T ] are 10.85, 9.65, 4.124, and 10.27, 6.64, 2.362 at 298.15°K for coesite and stishovite, respectively, in cal/(mole °K). Enthalpies of transition for phase changes were determined by solution calorimetry in a lead-cadmium-borate solvent at 697°C. The following values (in kcal/mole) were obtained upon adjustment to 298.15°K: quartz coesite (1.2 1 ± 0.15), quartz cristobalite (0.6 4 ± 0.15), quartz silica glass (2.1 5 ± 0.15), and cristobalite silica glass (1.5 1 ± 0.15). The enthalpy of coesite to 1070°K and the enthalpy of transformation for stishovite-silica glass were provided by means of a novel technique, "transposed-temperature" drop calorimetry. These data permit the delineation of P-T field phase boundaries for the stable equilibria coesite-quartz and coesite--stishovite, as well as for the metastable quartz-stishovite boundary, which are in reasonable agreement with the results of recent equilibrium and formation studies.

Affiliated with

Also associated with

No associations

Rating

Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-877450