Thermoluminescence and optically stimulated luminescence properties of the Eu2+-doped KMgF3 produced by a hydrothermal microwave method

Abstract

The purpose of this work is to study the optically stimulated luminescence (OSL) and thermoluminescence (TL) properties of the Eu2+-doped KMgF3 (KMgF3:Eu). KMF powders were synthesized by a microwave – assisted hydrothermal method. The structural phase identification was performed by X-ray diffraction combined with Rietveld refinement. The TL and OSL sensitivity due the annealing (800 °C in air) was also performed. Properties as TL glow curve, step-annealing OSL, stability of the OSL signal, dose response curve and minimum detectable dose were investigated. The results showed that KMgF3:Eu display TL peaks in a range suitable for dosimetry applications. TL measurements also show that the material has shallow traps with a TL peak at around 90 °C, responsible for a short time afterglow emission (phosphorescence). However, a pre-heating before each measurement can reduce the shallow traps signal contribution. The results showed that the OSL signal is due the same trap centers responsible for the TL signal in this material. The OSL signal does not decay completely over 300 s reading due to stimulation of trapped charges from very deep traps. The dose response signal was evaluated in a range from 0.1 Gy up to 100 Gy using beta 90Sr/90Y, showing a linear response over this range. The estimated fading of the OSL signal, using initial intensity signal was 4% in 24 h and 15% over one week. Considering the total OSL area and the first 10 s of OSL decay, no fading was observed for the first 24 h and the signal was 10% faded over one week.