Kinetic Analysis of TL Spectrum of ϒ-IrradiatedSrAl₂O₄:Eu²⁺, Dy³⁺Nanophosphor

Abstract- Thermoluminescence is a simple technique for studying the distribution of artificially created or naturally occurring point defects. In present work we are reanalyzing the Thermoluminescence response of Eu2+,Dy3+ doped SrAl2O4 nanophosphor at different irradiation dose of ϒ-rays, in accordance with new method of analysis. Orders of kinetics for different glow curves are recalculated. Order of kinetics values are not same as already reported in literature. As per new model order of kinetics depends on extent of retrapping and from reanalysis we can infer that all the reported TL responses of material under consideration are retrapping dominant process.

Keywords- Thermoluminescence, Orders of kinetics, Glow Curves, Irradiation Dose, Retrapping.

INTRODUCTION

Phosphor is luminescent material that emits light when exposed to radiation such as ϒ- ray,ultraviolet light, visible, infrared radiation or an electron beam. Thousands of phosphors have been synthesized, each one having its own characteristic colour of emission and period of time during which light is emitted after excitation ceases. Phos phors excited by ultraviolet, visible, and infrared radiation are used principally in the fluorescent lamps commonly employed for general illumination. Thermoluminescence (TL) is emission of light from some minerals and certain other crystalline materials. The light energy released is derived from electron displacements within the crystal lattice of such a substance caused by previous exposure to high-energy radiation. Heating the substance in suitable temperature range enables the trapped electrons to return to their normal positions, resulting in the release of energy. The intensity of the emission can be correlated to the length of time that a given substance was exposed to radiation; the longer the time allowed for the radiation to build up an inventory of trapped electrons, the greater the energy released. Because of this feature, thermo luminescence has been exploited as a means of dating, dosimetry and characterization of luminescent material. In the structure of the inorganic phosphors there exist point defects, naturally occurring or artificially created, which induce electronic states in the forbidden band; these defects have great importance on understanding the TL phenomenon [1-5]. It is a simple, efficient, convenient and relatively inexpensive experimental technique to study various aspects of the role of defects and impurities in solids with considerably reliability [6-8].
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