Search Results
Over recent decades the uses of thermoluminescence have been expanding rapidly, as have advances in the equipment available for the determinations of this property shown by many materials. Despite this, the comparable growth of applications in the Earth and Archeological Sciences has been markedly overlooked in the mainstream thermal analysis literature, an omission this review sets out to rectify.
Abstract
Thermoluminescence and optical properties of LiF:Mg,Cu,P; BaSO4:Dy; BaSO4; Eu and α-Al2O3:C were investigated as a part of a broader research project on TL mechanisms in various materials. The effects of ionizing radiation on these phosphors are determined in this work by means of thermoluminescence and optical absorption experiments with the aim of identifying new defects formed in these systems and of testing dosimetric characteristics.
This study was aimed at evaluating the efficacy of different mineral separation procedures to validate the EN1788 (2001) European Union standard protocol for better identification of irradiated fish and shellfish. The silicate minerals were isolated with physical density separation method from two types of non-irradiated freeze-dried fish and shellfish that included Pacific saury (Cololabis saira), mackerel (Scomber japonicus), shrimp (Penaeidae metapenaeus), and mussel (Mytilus coruscus). Radiation-specific thermoluminescence (TL) peaks (glow curve 1) were observed between 150–250 °C. The peaks are typical for the irradiated food; despite the samples being not irradiated. Apparently it showed that the isolated minerals were contaminated with organic materials such as bone, etc. Acid-hydrolysis digestion was employed to remove the possible contaminants. The minerals obtained through alternative pre-treatment showed no TL curves in radiation specific temperature range. Moreover, acid hydrolysis extraction resulted in producing higher mineral yields and lower background luminescence. Results were also confirmed by calculating TL ratios (glow curve 1/glow curve 2) to confirm the irradiation history of samples. Furthermore, different time and temperature treatments on TL intensity of irradiated standard quartz (SiO2) minerals showed that the acid-hydrolysis can be adjusted to 50 °C and 3 h for better luminescence determinations.
Abstract
The thermoluminescence (TL) after excitation by UV or X-rays radiation of doped a-alumina powders is investigated. In the case of zirconia, the alumina-zirconia composites present five of the characteristic peaks of zirconia at -170, -145, -90, 0 and 95C. After a thermal treatment of mixed oxides, a new peak is observed at -35C in TL. This peak reveals the presence of stabilized tetragonal zirconia in the material. In the case of calcium, the TL curves of a-alumina doped by calcium present a double peak around 110 and 130C which can be attributed to the presence of the hibonite phase: CaAl12O19. Moreover, in the case of zirconia, by comparing this analysis with those realised by X-rays diffraction (XRD), it can be shown that the TL has one better limit of detection than the XRD.
Abstract
Thermoluminescence signals of irradiated and unirradiated spices and herbs are due to inorganic matter grains adhering to the surfaces. This study reports the mineral composition of this dust being, mainly quartz, calcite and philosilicates; it shows the differences between samples exposed and non-exposed to 
-radiation on the basis of TL signals after long storage periods (1–16 months). A saturation process in the TL signal is found when the samples absorb doses higher than 5 kGy. Finally, the TL glow curve intensities do not suffer significant changes with the dose rate of the -source used in the radiation process.
Abstract
Studies were conducted to measure the effect of irradiation treatment on thermoluminescence (TL) values in dried fruits such as apricots, dates and raisins. For this purpose, inorganic dust particulate (minerals) adhering to the fruit surface was collected from untreated and treated (0.5, 1.0 and 1.5 kGy) samples. The TL responses of the isolated minerals was measured in the temperature range of 80–320°C at an increasing rate of 10°C/s. It was observed that peak of the TL signals appeared at 200°C in each case and generally the magnitude of the peak signals was almost 103 times that of unirradiated samples. Regression and correlation analysis of the data indicated strong relationship between radiation absorbed dose and TL values at each temperature (r≥0.98). It was concluded that TL measurements could serve as a fast and reliable method for distinguishing as well as determining absorbed dose in irradiated dried apricot, date and raisin.
Abstract
We present measurements of Thermoluminescence (TL) from Greek marble quarried at Paros, Naxos, Pendeli, Hymitos, Thassos, which have been known since ancient times. The results concern i) the solar bleaching of TL, ii) the solar transmission through marble thicknesses up to 16 mm, and iii) the implications for potential dating of ancient carved marble monuments/objects. The bleaching rate for marbles is very fast during the first hour of exposure. The solar penetration is at least 35 mm for long exposures. Beyond the 2 mm marble slab for exposure times 90–120 hours of sunshine, the residual bleached TL level is not reached. The bleached TL reaches a plateau which serves as the “zero time” upon which the archaeological TL dose subsequently builds up and gives the age of a marble monument.
Investigations on the thermoluminescence of LaOBr∶Tb3+ phosphors
I. Experimental results
Thermoluminescence measurements are thermoanalytical techniques that allow study of the thermally stimulated relaxation processes in solids, yielding qualitative information on the mechanism of energy storage and permitting calculation of quantitative trap-spectroscopic parameters, too.
Abstract
A mixture of equal quantities of powdered LiF and NaF was doped with 0.2% each of Ti, Mg and Mn and heated to obtain a LiF+NaF phosphor. After grinding and sieving, the thermoluminescent phosphor was used to obtain the thermoluminescence characteristics such as the glow curve; the dose-response curve, sensitivity, reproducibility and linearity were all established. The main goal was to introduce two new methods for the calculation of trap energy: the single-peak-differential and single-peak-integration methods, both modifications of the basic method of Randall-Wilkins. The plots used to calculate the trap energy were In[(dα/dT)1/(1-α)]vs. 1/T and ln[ln(1-α)/(T o-T)]vs. 1/T, respectively. These linear plots with slopes of (E/k) gave trap energies ofE=0.547 eV andE=0.551 eV, respectively.
Abstract
Soil thermolumicenscence (TL), one of the methods for uranium exploration, is based on the glowing characteristics of the crystal minerals such as quartz in the nature. The paper deals with the experiments at Xiazhuang uranium ore-field, in order to show the availability of the thermoluminescence to explore granite-hosted uranium mineralization. Meanwhile, some constraints for application are discussed.
