THERMOLUMINESCENCE BEHAVIOUR IN THE KBr : Sm3+ Tb3+ SINGLE CRYSTALS

Abstract

KBr: Sm3+Tb3+ crystals were successfully grown by Bridgemann Stockbarger technique. Thermoluminescence
(TL) properties of these crystals were investigated. Before taking the TL ,the sample annealed at 400° C and then
irradiated at a γ –ray dose of 5 Gy. The TL glow curve was recorded after the samples were irradiated with γ-rays for
1-hour with the heating rate of 5°C/sec. The TL glow peak deconvoluted using the Origin 5.0 software. The deconvoluted
glow peak reveals two clearly visible distinct peaks at temperature around 448K and 501K. The various parameters such
as geometric factor, Activation energy and Frequency factor were found out using Chen’s peak shape method. The
calculated kinetic parameters show that both peaks follow the second order kinetics. The high temperature peak at 501K
is due to high energy traps and it is very useful for TL dosimeter (TLD) phosphor characteristics. The deconvoluted TL
emission spectrum for the glow peak at 501K shows two well separated peaks centered at 583nm and 644nm which
confirms emission is only due to samarium ions. Scanning electron micrographs (SEM) of KBr: Sm3+ Tb3+ crystals, it is
found the particles are cubic in shape with various sizes ranging from few microns to 10 microns and also cluster is
found. The micron size of crystallite from SEM image is best suited for dosimetric applications.