Elastic instability in. alpha. -quartz under pressure

Journal Article · Mon Oct 12 04:00:00 EDT 1992 · Physical Review Letters; (United States)

DOI:https://doi.org/10.1103/PhysRevLett.69.2220· OSTI ID:7081379

Binggeli, N; Chelikowsky, J R ^[1]

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1. Department of Chemical Engineering and Materials Science, University of Minnesota and Minnesota Supercomputer Institute, Minneapolis, Minnesota 55455 (United States)

The elastic properties of {alpha}-quartz are studied as a function of pressure using both a classical interatomic potential, and a first-principles pseudopotential approach. In both cases, we find that the structure becomes mechanically unstable at about 30 GPa. Our results suggest that the amorphization of quartz observed experimentally in this pressure range is triggered by the onset of a lattice shear instability. We analyze the microscopic origin of the elastic softening, and relate to the presence of an oxygen close-packed cubic arrangement in the quartz high-pressure structure. A change in the Si coordination is found to be intimately related to the shear instability.

• DOE Contract Number: FG02-89ER45391
• OSTI ID: 7081379
• Journal Information: Physical Review Letters; (United States), Journal Name: Physical Review Letters; (United States) Vol. 69:15; ISSN PRLTA; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
AMORPHOUS STATE
CHEMICAL BONDS
COORDINATION NUMBER
DIAGRAMS
ELASTICITY
INSTABILITY
MECHANICAL PROPERTIES
MINERALS
OXIDE MINERALS
PHASE DIAGRAMS
PHASE STUDIES
PRESSURE EFFECTS
QUARTZ
SHEAR PROPERTIES
TENSILE PROPERTIES
VERY HIGH PRESSURE