Particle size effect on TL emission of ZnS nanoparticles and determination of its kinetic parameters

Abstract

Nanoparticles have large surface area, and most of the ions are lying on its surface. Could these surface ions be contributed in thermoluminescence emission or enhanced nonradiative transition? In view of this, we have prepared small sizes of ZnS nanoparticles at low temperature and made two samples, one as-prepared (size ∼3nm) and the other heat-treated at 1073K (size ∼32nm). Characterization of the samples shows that the prepared phosphors are pure. Thermoluminescence (TL) glow curves could not be recorded in both samples without irradiation. Even for higher dose of γ-radiation the as-prepared samples could not show TL signal, but 1073K heat-treated sample shows the TL signal. This may be due to the fact that smaller particles have large surface area compared to bigger particles, the surface ions may produce the nonradiative transitions. The kinetic parameters of the TL glow curves are evaluated by the conventional methods and compared with curve fitting computerised glow curve deconvolution (CGCD) technique. The variations in both techniques are found only ± 0.02. The shape factor of all the glow curves 0.48, and these TL glow curves could be fitted with order of kinetics 1.5. Copyright © 2012 L. Robindro Singh and S. Dorendrajit Singh.