Direct determination of coesite- stishovite transition by in-situ X-ray measurements
1976; Elsevier BV; Volume: 35; Issue: 1-3 Linguagem: Inglês
10.1016/0040-1951(76)90042-1
ISSN1879-3266
AutoresTakehiko Yagi, Syun-iti Akimoto,
Tópico(s)Nuclear materials and radiation effects
ResumoThe coesite—stishovite transition was determined over the temperature range 500–1100° C by means of in-situ X-ray measurements with NaCl as an internal pressure standard. A cubic-anvil type of high-pressure apparatus and a high-power X-ray diffraction system were used for this study. Based on Decker's new pressure scale (1971), the coesite—stishovite transformation curve was represented by the linear equation P(kbar) = (80 ± 2) + (0.011 ± 0.003)(° C). Both the transition pressure at 1000° C and the slope dP/dT obtained in the present investigation are a little smaller than the previous determinations by the quenching method. Comparison with the thermodynamic data suggests that some uncertainty is still involved in the determination of the entropy of stishovite.
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