Thermoluminescence of Beta Particle Irradiated LiMgF 3 :X (X=Ce, Er)
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Thermoluminescence of Beta Particle Irradiated LiMgF3:X (X=Ce, Er) I. C. Muñoz 1, F. Brown 2, R. I. Baldenevro 1, V. R. Orante-Barrón 2, C. Cruz-Vázquez 2, C. Furetta 2, R. Bernal 3 1 Departamento de Ciencias Químico Biológicas, Universidad de Sonora. 2 Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Apartado Postal 130, Hermosillo, Sonora 83000 México 3 Departamento de Investigación en Física, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83190 México. ABSTRACT The thermoluminescence (TL) properties of beta particle irradiated Ce and Er doped LiMgF3 phosphors are presented. Pellet-shaped samples were prepared by cool-pressing 74 μm size particle powder, followed by thermal annealing at 700 °C during 5 h in air atmosphere. Some samples were irradiated with beta particles in the dose range from 8 up to 128 Gy. The sensitivity of Er doped samples was greater than the one of Ce-doped. In both cases, a 2 % mol of dopant concentration was used. The TL fading was between 19 % for Ce-doped samples, and 24 % for the Er-doped. The integrated TL increases as dose increases, with no saturation clues. The TL sensitivity of samples exhibited a loss in successive irradiation – readout cycles. INTRODUCTION The increasing interest in the development of new high performance phosphors useful as detectors and dosimeters is due to the successful application of the thermoluminescence (TL) technique in a diversity of fields involving the use of ionizing radiation, including environmental, clinical, and more recently, retrospective dosimetry. In this concern, the KMgF3 ternary compound synthesized using the Kyropoulus technique has been proposed as a promissory sensitive phosphor [1-6]. However, the KMgF3 material has a drawback caused by the presence of the natural isotope K-40 which induces a TL signal superimposed to the TL emission due to the external emission [7]. Although the self-dose effect is very little, a new perovskite has been proposed using Li instead of K, i. e., LiMgF3. In this work, we report the thermoluminescence properties of beta particle irradiated of Ce-doped and Er-doped LiMgF3.
EXPERIMENTAL DETAILS LiF, MgF2 salts were mixed with ErF3 or CeF3 into a platinum crucible and heated at 850 °C in nitrogen atmosphere. The ErF3 and CeF3 impurities were added at 2 % mol. The growth of the crystals was obtained with the pulling method, from the above melt, starting the process with an air-cooled platinum finger. Polycrystalline ingots were then obtained, crushed, and the 74 μm size particles selected by sieving. 0.06 g of the sieved powder were weighted and pressed at 0.5
ton during 3 min in a Carver model C hydraulic press to get 6 mm diameter and 1 mm thickness. The pellet samples were sintered at 700 °C during 5 h in a Jelrus-M furnace. A Risø TL/OSL model TL/OSL-DA-20 unit equipped with a 90Sr beta radiation source was used to perform beta irradiations and the TL measurements. All irradiations were accomplished using a 5 Gy/min dose rate at room temperature (22 °C).
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