ISSN:
1432-2021
Schlagwort(e):
Key words X-ray diffraction
;
High-temperature
;
Oxides
;
Thermal expansion
;
Anharmonicity
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Geologie und Paläontologie
,
Physik
Notizen:
Abstract The high-temperature cell parameters of lime (CaO), periclase (MgO), corundum (Al2O3), and spinel (MgAl2O4) have been determined from 300 up to 3000 K through X-ray diffraction experiments with synchrotron radiation. The good agreement found with dilatometric results suggests that vacancy-type defects do not make a large contribution to thermal expansion for these oxides, even near the melting point, justifying the use of X-ray diffraction for determining volume properties up to very high temperatures. Thermal expansion coefficients were determined from the measured cell volumes with equations of the form α=α0 + α1 T + α2/T 2. Along with available isobaric heat capacity and compressibility data, these derived coefficients clearly show that anharmonic effects contribute little to the isochoric heat capacities (C v ) of CaO, MgO, and Al2O3, which do not depart appreciably from the 3nR Dulong and Petit limit.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s002690050246
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