New insights into the melting behavior of MgO from molecular dynamics simulations: The importance of premelting effects

被引:34
作者
Aguado, A [1 ]
Madden, PA
机构
[1] Univ Valladolid, Dept Fis Teor, E-47011 Valladolid, Spain
[2] Univ Oxford, Dept Chem, Oxford OX1 3QZ, England
关键词
D O I
10.1103/PhysRevLett.94.068501
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
We provide a plausible resolution of a long-standing controversy relevant to the geophysics community, namely, that the experimental slope of the melting curve T-m(P) of MgO at low pressures is about 3 times smaller than that obtained from computer simulation of the melting of the normal rock-salt-structured crystal. With increasing temperature at zero pressure, our simulations predict a solid-solid phase transition (from a rock salt to a wurtzite crystalline lattice) to occur just before melting. The coexistence of wurtzite and liquid phases at low pressures is found to be described by a Clapeyron slope which is in much better agreement with the experimental results of Zerr and Boehler [Nature (London) 371, 506 (1994)] than the calculated melting line for the rock salt structure. We also show that the existence of a certain concentration of lattice defects in the rock salt phase cannot provide an alternative explanation.
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页数:4
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