Electron life time (τ) in trap levels of Dy3+ activated calcium aluminate: Implications in TL dosimetry

Abstract

RE3+ (Rare Earth) activated calcium aluminates (CaAl2O4) form an excellent class of phosphors for various applications. The multi-functionality of this class of phosphor is tailored by optimising the relative concentration of the trap-levels within the large band gap (Eg=7.4eV). In this paper we determine the trap-levels in Dy3+ activated nanocrystalline calcium aluminate (CaAl2O4: Dy3+) phosphor by rigorous analysis of the complex TL curves by computerised-glow-curve-deconvolution (CGCD) technique. We assume the kinetics to be the general order kinetic (1≤ b ≤ 2). Six trap levels have been identified with a lifetime ranging from 8 hours to 108 years at room temperature. The ones with τ300 = 6.46×1005 years, 1.02×1007 years and 9.02×1008 years in principle can be the candidates for TL dosimetric application.