Silicon micromachined calorimeters ("calorimeter on a chip") are used to measure heat capacities and phase transition enthalpies for thin film, single crystal, and powder samples (5-500 μg). The technology is thus compatible with the small samples produced in multianvil and large diamond anvil cells. Techniques for handling small samples and attaching them to the calorimetric devices have been developed. Initial data illustrate application to CoO and to Fe2SiO4 olivine and spinel, a quenched high pressure phase metastable at ambient conditions. The calorimetric entropy of the olivine - spinel transition in Fe2SiO4 (-16 ± 5 J/mol·K) is in good agreement with that calculated from phase equilibrium data (-14 ± 3 J/mol·K). A magnetic transition in iron silicate spinel, detected previously by Mossbauer spectroscopy, is seen in the calorimetric signal.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - May 29 2007|
- FeSiO spinel
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