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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) Silica Molecules -- Models Cristobalite Nanostructures |
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). |
URI: | https://www.um.edu.mt/library/oar//handle/123456789/18602 |
Appears in Collections: | Scholarly Works - FacSciChe Scholarly Works - FacSciMet |
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MOLECULAR MODELLING OF THE DEFORMATION MECHANISMS ACTING IN AUXETIC SILICA.pdf Restricted Access | Molecular modelling of the deformation mechanisms acting in auxetic silica | 406.36 kB | Adobe PDF | View/Open Request a copy |
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