Mobile interstitial model and mobile electron model of mechano-induced luminescence in coloured alkali halide crystals |
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Authors: | B P Chandra Seema Singh Bharti Ojha R G Shrivastava |
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Institution: | (1) Department of Postgraduate Studies and Research in Physics, Rani Durgavati University, 482 001 Jabalpur, India;(2) Department of Physics, Government Engineering College, 482 001 Jabalpur, India |
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Abstract: | A theoretical study is made on the mobile interstitial and mobile electron models of mechano-induced luminescence in coloured
alkali halide crystals. Equations derived indicate that the mechanoluminescence intensity should depend on several factors
like strain rate, applied stress, temperature, density of F-centres and volume of crystal. The equations also involve the
efficiency and decay time of mechanoluminescence. Results of mobile interstitial and mobile electron models are compared with
the experimental observations, which indicated that the latter is more suitable as compared to the former. From the temperature
dependence of ML, the energy gaps between the dislocation band and ground state of F-centre is calculated which are 0.08,
0.072 and 0.09 eV for KCl, KBr and NaCl crystals, respectively. The theory predicts that the decay of ML intensity is related
to the process of stress relaxation in crystals. |
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Keywords: | Mechanoluminescence triboluminescence colour centres dislocations alkali halides |
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