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Structural phase transition in lanthanum monochalcogenides induced by hydrostatic pressure
Author(s) -
Varshney Dinesh,
Kaurav N.,
Sharma P.,
Shah S.,
Singh R. K.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200405241
Subject(s) - hydrostatic pressure , van der waals force , chemistry , phase transition , coulomb , phase diagram , ion , polarizability , lanthanum , thermodynamics , ionic bonding , condensed matter physics , phase (matter) , physics , molecule , inorganic chemistry , quantum mechanics , organic chemistry , electron
An effective interionic interaction potential (EIOP) is developed to investigate the pressure induced phase transitions from NaCl‐type ( B 1) to CsCl‐type ( B 2) structure in lanthanum monochalcogenides LaX [X = S, Se, Te] compounds. The long range Coulomb, van der Waals (vdW) interaction and the short‐range repulsive interaction up to second‐neighbor ions within the Hafemeister and Flygare approach with modified ionic charge are properly incorporated in EIOP. The vdW coefficients are computed following the Slater–Kirkwood variational method, as both the ions are polarizable. The estimated value of the phase transition pressure ( P t ) and the magnitude of the discontinuity in volume at the transition pressure are consistent with the reported data. A large volume discontinuity in the pressure‐volume phase diagram identifies the structural phase transition from B 1 to B 2 structure. We also study the second order elastic constants for these La compounds. It appears that the vdW interaction is effective in determining the elastic and structural properties of these test compounds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)