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Structural phase transformations and new intermediate phases of MgF2 under high pressures applied via conjugate gradient method       
Yazarlar
Prof. Dr. Hülya ÖZTÜRK
Ahi Evran Üniversitesi, Türkiye
Cemile Kürkçü
Doç. Dr. Cihan KÜRKÇÜ
Ahi Evran Üniversitesi, Türkiye
Özet
An ab initio constant pressure technique is performed in order to study the structural behavior of MgF2 under the hydrostatic pressure up to 700 GPa. Two high-pressure phases of MgF2 are successfully observed through constant pressure simulations. MgF2 undergoes a phase transformation from the rutile-type structure to the cubic-fluorite-type structure with space group Fm(3) over bar m at 280 GPa. Another phase transformation from the cubic-fluorite-type structure to the cotunnite-type structure with space group Pnma occurs at 500 GPa. The first transformation proceeds via three intermediate phases with space groups Pnnm, Immm and R(3) over bar m. We also investigate the stability of these phases from the total energy and enthalpy computations. According to these investigations, the phase transformations should occur from the rutile-type structure to the cubic-fluorite-type structure around 20 GPa and from the cubic-fluorite-type structure to the cotunnite-type structure around 45 GPa. (C) 2014 Elsevier B.V. All rights reserved.
Anahtar Kelimeler
Magnesium fluoride, Intermediate phase, Phase transformation, Molecular dynamics
Makale Türü Özgün Makale
Makale Alt Türü SSCI, AHCI, SCI, SCI-Exp dergilerinde yayımlanan tam makale
Dergi Adı Journal of Alloys and Compounds
Dergi ISSN 0925-8388
Dergi Tarandığı Indeksler SCI-Expanded
Makale Dili İngilizce
Basım Tarihi 10-2014
Cilt No 609
Sayfalar 185 / 191
Doi Numarası 10.1016/j.jallcom.2014.04.152
Makale Linki http://linkinghub.elsevier.com/retrieve/pii/S0925838814009827