Anomalous elastic behavior in crystalline silica

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.16227· OSTI ID:5550398

Keskar, N R; Chelikowsky, J R ^[1]

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

A low-density polymorph of silica, [alpha]-cristobalite, has been observed to have a [ital negative] Poisson ratio, i.e., when subjected to a uniaxial compression, this crystal contracts in the transverse direction. This behavior is uncommon. Other low-density polymorphs of silica, which have a similar chemical environment, have been reported to have [ital positive] Poisson ratios. We have investigated the elastic behavior of several silica phases: [alpha]-quartz, [beta]-quartz, and [alpha]-cristobalite, with first-principles quantum-mechanical calculations, and with interatomic potentials. Our calculations confirm a negative Poisson ratio in [alpha]-cristobalite. We predict that [alpha]-quartz will have a negative Poisson ratio at high tensile strains, and that [beta]-quartz will [ital never] assume a negative ratio. We compute the second-order elastic constants of [alpha]-quartz and [alpha]-cristobalite using interatomic potentials and apply them in discussing the anisotropy of Poisson ratios in these materials. We demonstrate that the rigidity of the SiO[sub 4] tetrahedral units is intimately related to the occurrence of negative Poisson ratios in crystalline forms of silica.

• DOE Contract Number: FG02-89ER45391
• OSTI ID: 5550398
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:22; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
CHALCOGENIDES
ELASTICITY
MECHANICAL PROPERTIES
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POISSON RATIO
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TENSILE PROPERTIES