Zihni Öztürk

The analysis of dosimetric thermoluminescent glow peak of -Al2O3 : C after different dose levels by -irradiation

The variable dose (VD), Tm?Tstop, initial rise, variable heating rate, peak shape and computerized glow curve deconvolution (CGCD) methods were used to determine the number of peaks, the order of kinetics (b), the activation energy (Ea) and attempt-to-escape frequency (s) associated with the dosimetric glow peak of ?-Al2O3?:?C after ?-irradiation at a dose level between 0.02 and 288?Gy. The Ea?Tstop and CGCD methods indicated that the dosimetric peak of this crystal is the superposition of at least two components (peak?2a and?2b). When the dose level reaches and exceeds saturation point, a third peak (peak 2c) is also evident on the low temperature side of the dosimetric peak. The VD and CGCD methods indicated that both components of the dosimetric peak have general-order kinetics that change with doses. The dose responses of peak?2a follow linear, supralinear, saturation and sublinear patterns, whereas peak?2b does not exhibit supralinear behaviour. They are saturated at different dose levels, peak?2a at D = 10?Gy and peak?2b at D = 5?Gy. Ea?Tstop plots obtained at two different dose levels (D = 10 and 1?Gy) indicated that the efficiency of thermal quenching effect on this sample is highly dependent on the dose level and decreases with increasing dose level, which also has pronounced effects on the evaluated kinetic and thermal quenching parameters of the dosimetric peak.

Structural and Optical Properties of Nanocrystal In2O3 Films by Thermal Oxidation of In2S3 Films

In2S3 nanocrystalline films are prepared on glass substrates by the spray pyrolysis technique using indium chloride and thiourea as precursors. The deposition is carried out at 350°C on glass substrates. The films are then annealed for two hour at 200, 400, 600, and 800°C in O2 flow. This process allows the transformation of nanocrystal In2O3 films from In2S3 films and the reaction completes at 600°C. These results indicate that the In2O3 film prepared by this simple thermal oxidation method is a promising candidate for electro-optical and photovoltaic devices.

Thermoluminescence properties of newly generated glow peak 3a in TLD-100 after pre-irradiation heat treatment at 150 °C

Abstract It is well known that the glow curve structure of TLD-100 highly depends on the pre-irradiation heat treatments. In this study, it was observed that a new glow peak at 175 °C (indicated as peak 3a) appears, located between peak 3 (160 °C) and peak 4 (190 °C) after pre-irradiation heat treatments at 150 °C for annealing times t a ⩾30 min when recorded at a heating rate of 2 °C/s. Our investigations have shown that this peak has different thermoluminescence (TL) characteristics from its neighboring peaks 3 and 4. Deconvolution analysis of its TL emission spectra indicates that it has at least three prominent emission bands at near 396, 406, 563 nm and another major emission band at around 469 nm depending on the annealing time duration. Its dose-response was also studied between 25 mGy and 400 Gy by using computer glow curve deconvolution (CGCD) technique and it was observed that it has a linear dose response between 25 mGy and 20 Gy and then a supralinear behavior. In the first month following irradiation, the fading of this peak was reported that less than 12%. Finally, the effect of additional heat treatments at 150 °C on its trapping parameters has been studied in detail by using the CGCD method as a function of annealing time. The results showed that its kinetic order ( b ) remains nearly constant during the heat treatments but its activation energy ( E a ) and frequency factor ( s ) extremely varies during the heat treatments.

Rapid pyrolysis of cellulose with reactive hydrogen gas in a single-pulse shock tube

The thermal decomposition of cellulose in a reactive hydrogen atmosphere (1 and 5 vol.% hydrogen in argon) and in pure argon was studied under conditions of high temperature (700–2200°C), very short reaction time (0.3–3.0 ms), high heating rates and rapid quenching in a single-pulse shock tube. Compared with the yields obtained in pure argon, the methane yield increased by a factor or 2 in 5 vol.% H2 and the CO yield decreased by ∼30–35 wt% in 1 and 5 vol.% H2 atmospheres. On the other hand, hydrogen exerted very little influence on the yields of C2H4 and C2H2. The onset of evolution of pyrolysis products was affected by the reaction time, which also influenced the product yields.

Studies on structural and electrical properties of MnO films prepared by the spray pyrolysis method

MnO film samples of various thicknesses were prepared by the spray pyrolysis technique via the atomization of MnCl2 aqueous solutions onto glass substrates held at 350 °C using compressed air as a carrier gas. The crystal structure of the MnO films that was determined by x-ray diffraction was found to be polycrystalline. The crystalline structure of all the film samples showed a preferred orientation along the c-axis perpendicular to the substrate. The electrical parameters of the samples were obtained by applying the dc four-probe technique to rectangular-shaped samples. The effect of temperature on the electrical properties of MnO films is described here.

Effect of Water Concentration on the Characterization of Sprayed Cd0.5Zn0.5S Films

Cd0.5Zn0.5S film samples are prepared by a spray pyrolysis technique using aqueous solutions of CdCl2, ZnCl2, SC(NH2)2 and deionized water, which are atomized using compressed air as the carrier gas onto glass substrates with different water (H2O) concentrations. H2O is used as the activator. The prepared films are characterized by means of XRD and UV-VIS spectroscopy. Experimental results reveal that the structures and properties of the films are greatly affected by the H2O content. Water in a certain range of concentrations promotes the formation of the Cd0.5Zn0.5S films and improves the properties of the films.

Effect of the grain size on the structural and optical properties of the sprayed Cd x Zn 1-x S films

Cd_xZn_1-xS films were obtained with incorporation of Cd element into ZnS at different concentrations (0≤x≤1) by spray pyrolysis technique using aqueous solutions of CdCl₂, ZnCl₂ and (CS(NH)₂)₂, which were atomized with compressed air as carrier gas. The CdxZn1-xS films were obtained on glass substrates at substrate temperatures of 400°C. Effects of the grain size of the films on structural and optical properties of sprayed cadmium zinc sulfide (CdZnS) films were investigated. It was seen that the crystallinity level of the films increased. with increasing x composition and grain size.