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Thermal Dissociation Energy of F‐Centers in Alkali Halides
Author(s) -
Dalal M. L.,
Sivaraman S.,
Murti Y. V. G. S.
Publication year - 1982
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.2221100140
Subject(s) - halide , alkali metal , chemistry , extrapolation , dissociation (chemistry) , thermal , analytical chemistry (journal) , crystal (programming language) , thiourea , bond dissociation energy , electrolyte , inorganic chemistry , thermodynamics , physics , programming language , mathematical analysis , mathematics , organic chemistry , chromatography , electrode , computer science
The electrolytic coloration process is employed to obtain the mobility of F‐centers in KI, KBr, KCl, and NaCl crystals by measuring the drift velocity of the color cloud, during its withdrawal as function of temperature. The motion of the color cloud is timed between two previously marked lines and the field was also measured between them. An optical arrangement is used to project the crystal on a screen. The thermal dissociation energy E F is deduced for all these crystals which comes out to be 2.33, 2.66, 2.88, and 2.45 eV for KI, KBr, KCl, and NaCl crystals, respectively. The variation of the ratio of the fields ( U un / U col ) in the colored and uncolored regions is also studied with temperature. A Mollwo‐Ivey type of relation is also tried between E F and various physical properties of the crystals, from the extrapolation of which the h S value for NaI is deduced which agrees very well with the reported value, where h S is the Schottky defect formation energy.