Effect of Flux Boric Acid (H3BO3) on Yttrium Silicate Y2SiO5:Dy3+ (9 mol%) Nanophosphors Its Characterization and Luminescence Studies

Flux Boric acid (H3BO3) doped on Y2SiO5:Dy3+ phosphors were synthesized by auto ignition based low temperature Solution Combustion Synthesis (SCS) using Oxalic acid dihydrate (ODH) as fuel. Powder X-ray diffraction (PXRD) patterns confirm the nano sized particles corresponding to JCPDS card 36-1476. The crystallite size of the samples estimated from Scherer's formula and Williamson-Hall (W-H) plots was found to be in the range ˜21 nm and 26 nm respectively. Scanning electron Microscope (SEM) micrographs infer addition of flux gives the enhanced grain growth and it attains smooth surface improves the crystallinity and particle morphology of the sample. Fourier transform Infrared (FTIR) data reveals the presence of M–O bonds and Y–O bonds and also the bands at 642 cm–1, 655 cm–1, 668 cm–1, 697 cm–1, 719 cm–1 are ascribed due to the B–O–B linkage in the borate network. Addition of flux on Thermoluminescence (TL) glow curves from 0.5 KGy–4 KGy acts as a sensitizer and the peak appearing at 185 °C is quite stable and can be named as "dosimetric peak" to use in TL phosphor. The kinetic parameters estimated by Chen's peak shape method was found to be second order with activation energy 0.82.

ANÁLISE TERMOLUMINESCENTE DE COMPÓSITOS DE CaSO4 ATIVADO COM TERRAS RARAS

Since the thermoluminescence started to be applied to the dosimetry of ionizing radiation in 1940 different materials detectors have been proposed, and one of the most common is CaSO4. The motivation of this work was to produce crystals of CaSO4 doped with rare earth elements such as europium (Eu), neodymium (Nd) and thulium (Tm). It was also produced crystals of CaSO4:Ag. The interest in the production of these materials was to investigate other methods of production of thermoluminescent materials. The results show that the CaSO4:Tm is more suitable for use in the thermoluminescent dosimetry. Although not the most intense peak, the peak at 170 °C could be a dosimetric peak. Analyses showed that all samples have a TL response proportional to the dose absorbed.

Thermoluminescence Behavior under Different Mega Voltage of Aluminates Based Phosphor

Phosphor material CaYAl3O7 with transition metal Mn2+ were prepared by combustion method at 500°C. The prepared phosphor material characterized for their crystallinity and nature by powder XRD and FTIR. For the thermoluminescecne study, the samples irradiated with 6MeV and 16 MeV. In this voltage phosphor exhibit TL spectra at 1900c that corresponding to dosimetric peak. From the observations and detailed kinetic parameter study shows that phosphor can be act as dosimeter.

Effects of Gamma and Beta Radiations to Dosimeters Fabricated from K₂YF₅ and K₂GdF₅

K2YF5 and K2GdF5 doped with rare earth can be used as thermoluminescent (TL) dosimeters for gamma, beta radiations. In this study, the K2YF5 and K2GdF5 doped with Tb, Pr, Sm, and Dy with different concentrations were synthesized by solid state reaction method. These double fluoride dosimeters were irradiated with different radiations, namely beta and gamma. The study results showed that in general, the TL intensity of K2GdF5 is higher than that of K2YF5. The K2GdF5 crystals doped with Tb3+, Pr3+ have very high TL sensitivities. But the sensitivities of Sm3+, Dy3+ doped- are very low. The TL glow curve of K2YF5:Tb consists of three peaks at temperatures 132oC, 207oC and 240oC, and its intensities are approximately. The TL glow curve of K2GdF5:Tb has dosimetric peak at the temperature 196oC (heating rate 2oC/s), the temperature of this peak suitable for dosimetry application. The TL sensitivity of K2GdF5:Tb is higher than that of TLD-100 and TLD-900 dosimeters for the gamma and beta radiation. The dosimeters K2GdF5:Tb has high sensitivity and linearity for gamma, beta radiations. In addition, the thermal fading effect of TL intensity was very low. The study results showed that these materials can be used in nuclear radiation dosimeters.

Synthesis and Thermoluminescent Properties of New ZnO Phosphors

In this work, results on the thermoluminescence dosimetry properties of beta particle irradiated ZnO obtained by thermal annealing of chemically synthesized ZnS are reported. ZnS powder was sintered at 950 °C during 24 h in air, in order to obtain pellet-shaped ZnO samples. The thermoluminiescence (TL) intensity of ZnO previously exposed to beta radiation increased as the dose increased in the 0.025-6.4 kGy interval studied. Characteristic glow curves exhibited two emission maxima at ~ 94 and ~ 341 °C. The dosimetric peak located at ~ 341 °C shifted towards lower temperatures as the dose increased, which indicates that second-order kinetic processes are involved in the thermoluminiescence emission. The dose response of ZnO showed a linear behaviour in the 0.025 Gy-0.8 kGy dose interval, which makes this material suitable and promising for medical, industrial and also space dosimetry applications. The thermoluminescence total signal faded down 48 % 6 h after irradiation and showed an asymptotic behaviour for longer times, due mainly to the ~ 341 °C stable and dosimetric glow peak.

Determination of ZrO2 Thermoluminescence Kinetic Parameters after UV Irradiation Using Peak Shape Methods

Various experimental methods are currently employed for the determination of the trap parameters. Methods based on the glow curve shape extract information from a glow peak utilizing the temperature at the maximum emission, TM, the temperature on the ascending part of the peak ,T1, which corresponding to half peak intensity and the temperature on the descending part of the peak, T2, also corresponding to the half peak intensity; as well as, the half width parameters and the symmetry properties. In order to obtain the kinetic order b and the trap parameters, ZrO2 samples were exposed to 260 nm ultraviolet radiation (UVR). The trapping kinetics parameters of the ZrO2 dosimetric peak using the shape of the glow curve were then determined. The order of kinetics followed by the main peak was also determined using the same method. The values of activation energy E and frequency factor ,s, for the main peak of ZrO2 obtained by the above mentioned methods, showed a good agreement among them.