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Shock induced polymorphic transition in quartz, carbon, and boron nitrideThe model proposed by Ahrens (1988) to explain the mechanism of the polymorphism in silicates is revised, and the revised model is applied to the quartz/stishovite, graphite/diamond, and graphite-boron nitride (g-BN) phase transformations. In this model, a key assumption is that transformation to a high-density amorphous or possibly liquid phase which rapidly crystallized to the high-pressure phase is triggered by the high temperatures in the shear band and upon crossing the metastable extension of a melting curve. Good agreement between the calcualted results and published data is obtained. The present theory predicts the standard entropy for cubic BN to be 0.4-0.5 J/g K.
Document ID
19900034314
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tan, Hua
(California Inst. of Tech. Pasadena, CA, United States)
Ahrens, Thomas J.
(California Institute of Technology Pasadena, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Journal of Applied Physics
Volume: 67
ISSN: 0021-8979
Subject Category
Nonmetallic Materials
Report/Patent Number
AD-A219614
Accession Number
90A21369
Funding Number(s)
CONTRACT_GRANT: DAAL03-88-K-0199
CONTRACT_GRANT: DNA001-87-C-0125
CONTRACT_GRANT: NGL-05-002-105
Distribution Limits
Public
Copyright
Other

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