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First-principles study on thermodynamic properties and phase transitions in TiS(2).
MedLine Citation:
PMID:  21406908     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Structural and vibrational properties of TiS(2) with the CdI(2) structure have been studied to high pressures from density functional calculations with the local density approximation (LDA). The calculated axial compressibility of the CdI(2)-type phase agrees well with experimental data and is typical of layered transition-metal dichalcogenides. The obtained phonon dispersions show a good correspondence with available experiments. A phonon anomaly is revealed at 0 GPa, but is much reduced at 20 GPa. The thermodynamic properties of this phase were also calculated at high pressures and high temperatures using the quasi-harmonic approximation. Our LDA study on the pressure-induced phase transition sequence predicts that the CdI(2)-type TiS(2), the phase stable at ambient conditions, should transform to the cotunnite phase at 15.1 GPa, then to a tetragonal phase (I4/mmm) at 45.0 GPa. The tetragonal phase remains stable to at least 500 GPa. The existence of the tetragonal phase at high pressures is consistent with our previous findings in NiS(2) (Yu and Ross 2010 J. Phys.: Condens. Matter 22 235401). The cotunnite phase, although only stable in a narrow pressure range between 15.1 and 45.0 GPa, displays the formation of a compact S network between 100 and 200 GPa, which is evidenced by a kink in the variation of unit cell lengths with pressure. The electron density analysis in cotunnite shows that valence electrons are delocalized from Ti atoms and concentrated near the S network.
Authors:
Yonggang G Yu; Nancy L Ross
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Publication Detail:
Type:  Journal Article     Date:  2011-01-19
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  23     ISSN:  0953-8984     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-03-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  England    
Other Details:
Languages:  eng     Pagination:  055401     Citation Subset:  IM    
Affiliation:
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA.
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