https://doi.org/10.1140/epjb/e2011-10857-y
Regular Article
High pressure phase transition and elastic behaviour of lanthanum monochalcogenides
1
Condensed Matter Theory Group, School of Studies in Physics,
Jiwaji University, 474011
Gwalior,
India
2
Department of Physics, Govt. K.R.G. P.G. Autonomous College,
474001
Gwalior,
India
a e-mail: sosfizix@gmail.com
Received:
9
November
2010
Received in final form:
29
July
2011
Published online:
3
November
2011
The Phase transition and elastic properties of La-monochalcogenides have been investigated under pressure by means of a modified charge-transfer potential model which incorporates the Coulomb interaction modified by Coulomb screening due to the delocalization of electron of rare-earth atom leading to many-body interactions, covalency effect and overlap repulsion extended up to second-nearest neighbours. Under high pressure the coordination increases and they transform from rock-salt to CsCl structure. The calculated values of cohesive energy, lattice constant, phase transition pressure, relative volume collapse, harmonic and anharmonic elastic moduli and their first- and second-order pressure derivatives agree well with the available measured data and better than those computed by earlier workers. Present model is capable of explaining the Cauchy’s discrepancy correctly.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2011