Alfredsson, M. and Cora, F. and Brodholt, J.P. and Parker, S.C. and Price, G.D. (2005) Crystal morphology and surface structures of orthorhombic MgSiO3 in the presence of divalent impurity ions. Physics and Chemistry of Minerals, 32 (5-6). pp. 379-387. ISSN 0342-1791.
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Many rheological and transport properties of rocks are determined by the grain boundary structures of their constituent minerals. These grain boundaries often also hold a high concentration of dopant ions. Here, as a first step towards modelling the transport and rheological behaviour of the lower mantle, we report the results of lattice static simulations on the surface structures of Fe2+ and Ca2+- doped orthorhombic MgSiO3-perovskite. For all the surfaces we studied, the energies of the doped structures are lowered, sometimes by more than 1 J/m(2), with respect to the pure surfaces. From our calculated crystal morphologies, we predict that the grains become more tabular as the concentration of Fe2+ ions increases, while under equilibrium conditions the grains are cubic. By calculating the replacement energies of Mg2+ by Fe2+ and Ca2+ ions in the six outermost surface layers, we conclude that these divalent ions would tend to segregate onto the crystal surfaces. We suggest, therefore, that the grain boundary structure and rheology of MgSiO3- perovskite dominated rocks will be strongly affected by the presence of minor elements in the lower mantle.
|Additional information:||ISI Document Delivery No.: 971GR Times Cited: 2 Cited Reference Count: 49|
|Uncontrolled keywords:||mantle rehology crystal shape perovskite simulation MAGNESIUM-SILICATE PEROVSKITE EARTHS LOWER MANTLE TRANSMISSION ELECTRON-MICROSCOPY COMPUTER-SIMULATION ATOMISTIC SIMULATION IRON DIFFUSION PRESSURE SRTIO3 MG|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group|
|Depositing User:||Maria Alfredsson|
|Date Deposited:||02 Sep 2008 20:39|
|Last Modified:||14 Jan 2010 14:17|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/4763 (The current URI for this page, for reference purposes)|
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