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- Title
MECHANOLUMINESCENCE GLOW CURVE OF ZnS:Mn.
- Authors
Chandra, B. P.; Baghel, R. N.; Chandra, V. K.
- Abstract
The curve between mechanoluminescence (ML) intensity and deformation and post-deformation time of a solid is known as ML glow curve. When a ZnS:Mn crystal is elastically deformed by applying a load at a fixed rate, then initially the ML intensity increases with time, attains a peak value Im at a particular time tm., and later on it decreases with time. After tm, initially the EML intensity decreases exponentially at a fast rate and then it decreases exponentially at a slow rate, in which the decay time of fast decrease in EML intensity is equal to half of the decay time of piezoelectric charges. For a given strain rate, whereas the peak intensity Im increases linearly with the magnitude of applied pressure, the total EML intensity IT increases quadratically with the magnitude of the applied pressure. The ML spectra of ZnS:Mn crystals are similar to their photoluminescence and electroluminescence spectra. The elastico ML in ZnS:Mn crystals can be understood on the basis of the piezoelectrically-stimulated electron detrapping model ,in which the local piezoelectric field near the Mn2+ centres reduces the trap-depth, and therefore, the detrapping of filled electron traps takes place, and subsequently the energy released non-radiatively during the electron-hole recombination excites the Mn2+ centres and de-excitation gives rise to the ML. On the basis of the piezoelectrically-stimulated electron detrapping model, expressions are derived for different characteristics of the EML of ZnS:Mn crystals and a good agreement is found between the theoretical and experimental results. The expressions explored for the dependence of EML intensity on several parameters may be useful in tailoring the suitable materials capable of exhibiting ML during their elastic deformation. The values of the decay time of piezoelectric charges, time-constant for the rise of pressure, pressing rate, strain rate and the threshold pressure for EML emission can be determined from the measurement of the ML glow curve.
- Subjects
ELECTRIC properties of zinc; ELECTROLUMINESCENCE; PHOTOLUMINESCENCE; LUMINESCENCE; PARTICLES (Nuclear physics); MECHANORECEPTORS; QUASIELASTIC light scattering; PIEZOELECTRIC devices; EXTENDED ML (Computer program language); SEMICONDUCTORS; SPECTRUM analysis
- Publication
Chalcogenide Letters, 2010, Vol 7, Issue 1, p1
- ISSN
1841-4834
- Publication type
Article