J. Azorín Nieto

Synthesis and characterization of hafnium oxide films for thermo and photoluminescence applications

Hafnium oxide (HfO(2)) films were deposited by the ultrasonic spray pyrolysis process. The films were synthesized from hafnium chloride as raw material in deionized water as solvent and were deposited on corning glass substrates at temperatures from 300 to 600 degrees C. For substrate temperatures lower than 400 degrees C the deposited films were amorphous, while for substrate temperatures higher than 450 degrees C, the monoclinic phase of HfO(2) appeared. Scanning electron microscopy showed that the films surface resulted rough with semi-spherical promontories. The films showed a chemical composition close to HfO(2), with an Hf/O ratio of about 0.5. UV radiation was used in order to achieve the thermoluminescent characterization of the films; the 240 nm wavelength induced the best response. In addition, preliminary photoluminescence spectra, as a function of the deposition temperatures, are shown.

Thermoluminescence and optical characteristics of zrO2 powder as a TL dosimeter

A description of the preparation of zirconium oxide (ZrO2) polycrystalline powder by the sol–gel method is presented. To prepare ZrO2 powder to be used as a thermoluminescent (TL) phosphor in dosimetric application, it is necessary to analyze some structural properties before, such as it’s crystallinity. In this work, the property was verified using X-ray diffraction. ZrO2 polycrystalline powder obtained was subjected to thermal treatment by heating up to 1000 °C. Both the absorption spectrum and the emission spectrum were also studied. The TL glow curve of ZrO2 powder exhibited a peak when it was exposed to a radiation field. Results of analyzing optical properties and the preliminary results of studying the TL in ZrO2, indicate that the latter is a good candidate to be used as a TL dosimeter in radiation ionizing and UV-radiation fields.

Thermoluminescence and photoluminescence characteristics of K2YF5: Tb3++PTFE irradiated with 90Sr/90Y beta particles

This article presents results of thermoluminescence (TL) and photoluminescence (PL) measurements performed on beta-irradiated K 2YF 5:Tb 3++PTFE pellets. K 2YF 5 crystals doped with 0.1% of trivalent optically active Tb 3+ ions in pellets form were investigated. The TL glow curve of K 2YF 5:Tb 3++PTFE has a simple structure with two well-defined peaks centered at 170 and 307 °C. The TL sensitivity of the K 2YF 5:Tb 3++PTFE irradiated with beta radiation was found to be higher than that of commercial phosphor TLD-100 (LiF:Mg,Ti), at the same conditions of irradiation and readout. Moreover, PL measurements performed on the terbium doped material show the presence of Terbium as Tb 3+ in the material.

Thermoluminescence characteristics of hydrogenated amorphous zirconia

This paper reports the experimental results concerning the thermoluminescent (TL) characteristics of hydrogenated amorphous zirconium oxide (a-Zr:H) powder prepared by the sol–gel method. The advantages of this method are the homogeneity and the purity of the gels associated with a relatively low sintering temperature. Hydrogenated amorphous powder was characterized by thermal analysis and X-ray diffraction. The main TL characteristics investigated were the TL response as a function of the absorbed dose, the reproducibility of the TL readings and the fading. The undoped a-Zr:H powder presents a TL glow curve with two peaks centered at 150 and 260 °C, respectively, after beta irradiation. The TL response a-Zr:H as a function of the absorbed dose showed a linear behavior over a wide range. The results presented open the possibility to use this material as a good TL dosimeter.

Termoluminescent Properties of High Sensitive ZrO2+PTFE for UV Radiation Dosimetry

This paper presents the preparation method, luminescent characteristics and the results of studying the thermoluminescence (TL) properties of zirconium oxide (ZrO2) exposed to 260 nm ultraviolet radiation. The glow curve of ZrO2+PTFE pellets exhibited one peak centered at 180°C about 30°C lower than that the commercially available aluminum oxide peak (Al2O3:C). TL response as a function of spectral irradiance showed good linear in the range from 2.4 to 3000 µJ/cm2 of spectral irradiance. Experimental results of studying the thermoluminescent (TL) properties of ZrO2+PTFE exposed to ultraviolet radiation allow to propose zirconium oxide as an excellent candidate as ultraviolet radiation dosimeter.

Electron absorbed dose measurements in LINACs by thermoluminescent dosimeters.

In this work, electron absorbed doses measurements in radiation therapy (RT) were obtained. Radiation measurements were made using thermoluminescent dosimeters of calcium sulfate doped with dysprosium (CaSO4:Dy) and zirconium oxide (ZrO2). TL response calibration was obtained by irradiating TLDs and a Farmer cylindrical ionization chamber PTW 30013 at the same time. Each TL material showed a typical glow curve according to each material. Both calcium sulfate doped with dysprosium and zirconium oxide exhibited better light intensity to high energy electron beam compared with lithium fluoride. TL response as a function of absorbed dose was analyzed. TL response as a function of high energy electron beam was also studied.

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.