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Title: Thermal quenching of fracto-induced mechano luminescence emission in (ZnS:ZnO):Cu phosphors
Authors: Muraleedharan, R
Khokhar, M S K
Chandra, B P
Issue Date: May-1999
Publisher: NISCAIR-CSIR, India
Abstract: Studies on the temperature quenching of fracto-induced mechano luminescence (ML) emission of II-VI compounds with reference to mixed zinc sulphide-oxide powder phosphors activated with copper have been carried out by an impact of a moving piston on the phosphors under varying conditions of sample preparation. A comparative study of temperature dependence of electro luminescence (EL) and photo luminescence (PL) of (ZnS: ZnO): Cu powder phosphors have also been investigated. It has been observed that the luminous intensity decreases with temperature of the phosphor and disappears beyond a critical temperature in all the 3 cases. The temperature dependence of mechano luminescence (ML) in the present case follows the relation I/(T)=Io (1-T/Tcn where n has the value around 1.2 and Tc being the critical temperature at which the ML disappears. The decrease in ML intensity is at a faster rate (time-wise) than in EL and PL. The peaks corresponding to transient and delayed emissions in the ML intensity curves shift towards longer time scale as temperature is increased. Though the overall shape of the ML intensity versus time curves remains the same at different temperatures, the peak corresponding to delayed ML emission undergoes considerable decrease with rise in temperature. The faster rate of decrease of ML intensity with temperature suggests that in addition to increase in the non-radiative transition probability, other parameters responsible for ML excitation such as surface charge density, piezo-electric constants etc. are also affected by temperature.
Page(s): 399-403
ISSN: 0975-1041 (Online); 0019-5596 (Print)
Appears in Collections:IJPAP Vol.37(05) [May 1999]

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