ISSN:
1432-2021
Keywords:
Key words Premelting
;
Heat capacity
;
Silicate minerals
;
Germanates
;
Thermodynamics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Abstract To provide a better thermodynamic description of premelting, the heat capacities of diopside, anorthite, pseudowollastonite, åkermanite, and CaMgGeO4 olivine have been determined from drop calorimetry measurements performed up to temperatures approaching the melting point. With the onset of premelting defined as the temperature at which the heat capacity begins to increase sharply, the premelting intervals of these minerals range from 80 to 250 K. Of the five compounds, pseudowollastonite exhibits the widest interval and åkermanite the lowest. Enthalpies of premelting range from 7 to 22% of the reported enthalpies of fusion. Correspondingly, the entropies of premelting vary from 5.4 to 18 J mol−1 K−1 and are consistent with temperature-induced mobility of cations as a general premelting mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002690050253
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