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Differential Thermal Analysis Investigation of the High‐Low Cristobalite Inversion Under Hydrostatic Pressure to 7 Kbar
Author(s) -
COHEN LEWIS H.,
KLEMENT WILLIAM
Publication year - 1975
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1975.tb11446.x
Subject(s) - cristobalite , differential thermal analysis , crystallite , quartz , hydrostatic pressure , mineralogy , analytical chemistry (journal) , hydrostatic equilibrium , high pressure , thermal , materials science , thermodynamics , chemistry , crystallography , diffraction , composite material , physics , optics , chromatography , quantum mechanics
The high‐low inversion in polycrystalline cristobalite, synthesized from quartz at 1500°C, was investigated by differential thermal analysis to 7 kbar in hydrostatic apparatus. A region of anomalous curvature ( d 2 T/dp 2 >0) exists to ∼1 kbar; at higher pressure, the low→high and high→low transition temperatures vary linearly with pressure, with slopes of ∼51. 1 and 53. 6 deg kbar −1 , respectively. Extrapolated 1‐bar intercepts are ∼232° and ∼209°C, respectively. It is concluded that high cristobalite is less compressible than low cristobalite near the inversion. The hysteresis between the high→low and low→high transition temperatures decreases with increasing pressure.