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Title: Molecular modelling of the deformation mechanisms acting in auxetic silica
Authors: Alderson, Andrew
Alderson, Kim L.
Evans, Kenneth E.
Grima, Joseph N.
Williams, M. R.
Davies, Philip J.
Keywords: Deformations (Mechanics)
Molecules -- Models
Issue Date: 2004
Publisher: Polish Academy of Sciences - Poznan Supercomputing and Networking Center
Citation: Alderson, A., Alderson, K. L., Evans, K. E., Grima, J. N., Williams, M. R., & Davies, P. J. (2004). Computational Methods in Science and Technology, 10(2), 117-126.
Abstract: Molecular mechanics simulations have been performed to undertake a systematic investigation into the structure and mechanical properties of α-cristobalite undergoing uniaxial loading along each of the 3 mutually orthogonal principal directions and also hydrostatic pressure loading. Simulations were performed using both the BKS and Burchart force-fields. The simulations indicate that pressure loading and uniaxial loading along the x3 direction leads to uniform variation of the four independent Si-O-Si intertetrahedral angles, indicative of cooperative tetrahedral rotation about tetrahedral axes which transform the α-cristobalite structure into the ‘idealised’ β-cristobalite structure. Uniaxial loading along either of the transverse directions (x1 and x2) leads to a divergence of the intertetrahedral angles, consistent with tetrahedral rotation about the tetrahedral axes which transform the idealised β-cristobalite structure into the ‘ordered’ β-cristobalite structure. The data also indicate that a phase transition to one of the proposed β phases may be induced by a negative hydrostatic pressure or tensile stress along x3. The phase transition is accompanied by a change in sign of some of the Poisson’s ratios (i.e. from positive to negative). A negative hydrostatic pressure is also predicted to lead to conversion of initially positive to negative Poisson’s ratio values (within the same phase).
Appears in Collections:Scholarly Works - FacSciChe
Scholarly Works - FacSciMet

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