High-pressure structural phase transitions and intermediate phases of magnesium fluoride
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We investigate the structural behavior of magnesium fluoride (MgF2) under the hydrostatic pressure using constant pressure ab initio technique up to 130 GPa. Through constant pressure simulations, two high-pressure phases of MgF2 are estimated. MgF2 undergoes a phase transformation from the rutile-type structure to the CaCl2-type structure with space group Pnnm at 10-20 GPa. Another phase transformation from the CaCl2-type structure to the alpha-PbCl2-type structure with space group Pnma occurs at 80-90 GPa. The later transformation is based on three intermediate phases with space groups P2(1)/m, P2(1) and P2(1)2(1)2(1). These phase transitions are also analyzed from the total energy and enthalpy calculations. These phase changes should occur around 9 and 35 GPa from enthalpy calculations, respectively. (C) 2014 Elsevier B.V. All rights reserved.