Phase barogramsaphase diagrams of vapor pressure: Eutectoid phase formation in binary systems

Phase barograms are specific representations of conventional (x, T) phase diagrams considering the vapor pressure as additional thermodynamic parameter. Thus, the determination of the vapor pressure is complementary to conventional DTA or DSC measurements. A stringent relationship between the phase...

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Bibliographic Details
Published in:Thermochimica acta 2012-08, Vol.541, p.1-7
Main Authors: Schmidt, Peer, Dao Quoc, Huong, Scholz, Tanja
Format: Article
Language:dut
Subjects:
Derivatives
Differential scanning calorimetry
Differential thermal analysis
Eutectoid temperature
Mathematical analysis
Phase diagrams
Thermodynamics
Vapor pressure
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Summary:Phase barograms are specific representations of conventional (x, T) phase diagrams considering the vapor pressure as additional thermodynamic parameter. Thus, the determination of the vapor pressure is complementary to conventional DTA or DSC measurements. A stringent relationship between the phase diagram and the corresponding phase barogram is derived by thermodynamic considerations of phase relations for complex heterogeneous equilibria. For that purpose, a derivative of the three-dimensional ClausiusaClapeyron equation is utilized. As a result, a validation of DTA/DSC measurements becomes feasible by the transformation of characteristic effects of vapor pressure measurements into thermal effects in conventional phase diagrams. The system CsBr/SeO2 is presented as a case study of systems with a eutectoid phase formation. CsSeO2Br is formed from the binaries at If = 180(5) [deg]C; the compound decomposes peritectically at Ip = 470(10) [deg]C.
ISSN:0040-6031
DOI:10.1016/j.tca.2012.04.022