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Deformation Bleaching of Coloration in Alkali Halide Crystals
Author(s) -
Chandra B. P.,
Vishwakarma H. L.,
Khare P. K.
Publication year - 1997
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 - 10.1002/1521-3951(199712)204:2<625::aid-pssb625>3.0.co;2-p
Subject(s) - halide , dislocation , electron , alkali metal , deformation (meteorology) , burgers vector , crystal (programming language) , radius , materials science , free electron model , chemistry , crystallography , physics , inorganic chemistry , composite material , quantum mechanics , computer security , organic chemistry , computer science , programming language
The present paper reports the phenomenological theory of deformation bleaching of coloration in alkali halide crystals. Expressions are derived for the dislocation capture probability of F‐centre electrons in alkali halide crystals, and for the rate of generation of electrons in the dislocation band. On the basis of the rate of generation of dislocation electrons and their subsequent recombination with hole centres, deep traps and other compatible traps (including deformation generated traps), an expression is derived for the deformation bleaching, which indicates the exponential decrease of the density of F‐centres with deformation of the crystal. A good agreement is found between the theoretical and experimental results. The value of the effective radius r e of the interaction of dislocations with F‐centres, is estimated and it is found to be 1.95 b , 2.00 b , 1.33 b and 1.70 b for KCl, KBr, NaCl and NaBr crystals, respectively (where b is the Burgers vector).