Influence of the alumina microstructure and composition in thermoluminescence for using in dosimetry

Among its various applications alumina may be used in thermoluminescent dosimeters (TLD) to radiations. The TLD are commonly used to determine the absorbed doses of radiation received in many application fields as nuclear installations, radiodiagnostic and radiotherapy in medicine. In this work it was developed a study of the influence of the microstructure, grain size and composition on the thermoluminescent properties in alumina (pure and carbon doped). The alumina and carbon powders used as starting materials were characterized by x-ray diffraction (XRD), chemical analysis, particle size distribution and surface area were determined by and BET analysis, respectively. The Al2O3 samples were sintered at 1650 deg C in air for one, three, five, seven and ten hours. The carbon doped samples were sintered using the same temperature for one hour, in a graphite resistance furnace in argon. Sintered materials were further characterised for phase composition and microstructure by XRD and scanning electron microscopy. The TL behaviour of the materials was also studied after they were submitted to a cobalt 60 gamma irradiator. The results obtained showed that the doped alumina do not possess dosimetric characteristics. For the alumina samples only those ones sintered during one and three hours showed satisfactory TL emission. After three hours of thermal treatment, it was observed that the TL properties decrease with sintering time. (author)