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Activation Energy of Substitutional Defects in Alkali Chlorides
Author(s) -
Bandyopadhyay S.,
Neogy C.,
Deb S. K.
Publication year - 1984
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.2221220113
Subject(s) - saddle point , ion , alkali metal , saddle , lattice energy , lattice (music) , activation energy , atomic physics , chemistry , chloride , condensed matter physics , crystal structure , physics , crystallography , geometry , organic chemistry , mathematical optimization , mathematics , acoustics
Based on a semi‐continuum model, the electrostatic, the polarisation, and the repulsive energy change of a lattice are calculated numerically, as functions of four different types of relaxations for the first fourteen ions of a substitutional defect in the saddle point position in an alkali chloride crystal. It is found that for a particular value of displacement, the total energy change of the lattice is minimum. A study of variation of the angle for the relaxed ions suggests further lowering of the lattice energy corresponding to a particular value of the angular displacement. These results are utilised in calculating the saddle point energy, the migration energy, and the activation energy for the motion of a host ion and a defect ion in NaCl, KCl, and RbCl crystals.