A.B. Tugrul

Refractive Index and Extinction Coefficient of ZnO:Al Thin Films Derived by Sol-Gel Dip Coating Technique

Doped ZnO:Al thin films were deposited on glass substrates by the solgel dip technique. Optical parameters such as the refractive index and the extinction coefficient tend to change with increasing annealing temperature.

Evaluation of Rubidium and Potassium Diffusion in Soil by Radiotracer Technique

In this study, diffusion of rubidium and potassium in soil was observed representing two alkaline elements. Generally, these elements are found as salt compounds in the earth. Soil columns were prepared in the laboratory conditions. Rubidium chlorite and potassium nitrate compounds were irradiated at ITU TRIGA Mark II nuclear research reactor at the Energy Institute of ITU to produce the radiotracer 86Rb and 42K. The irradiated compounds were sprinkled to the surface of different soil columns and were watered with realistic amounts. Radioactivity measurements were carried out by using a scintillation detector at the outside of the column for different soil depths in different diffusion times. As the results of the study, the behavior of two alkaline elements was observed appropriately similar in the soil.

Surface Characterization of Irradiated Zno:Al Thin Film by Reactor Neutrons

rradiation of ZnO:Al thin film by reactor neutrons with neutron/gamma ratio at 1.44x104 (n.cm-2.s-1.mR-1) leads to a decrease in resistivity in this material. The observed effects in electrical resistivity are attributed to irradiation-induced formation of defects in the ZnO:Al thin film structure.

Investigation of Salt Diffusion in Soil by Using Radiotracing Technique

In this study, it is aimed to observe diffusion of sodium in soil samples by using radiotracing technique. To produce the radiotracer 24Na, sodium-carbonate compound was irradiated at ITU TRIGA Mark II Research reactor at Energy Institute of Istanbul Technical University. The irradiated sodium-carbonate samples were sprinkled to the surface of soil columns. Then soil was watered with representative amounts of water according to selected rain regimes in Istanbul. Radioactivity measurements were carried out by using high efficiency gamma-ray measurement system at the outside of the column for different soil depths in different times.

Electromagnetic Radiation Effect on ZnO Nanocrystallites

The changes on energy band gap at induced ZnO nanocrystallite thin film have investigated with the increase of absorbed dose. Irradiated ZnO nanocrystallite thin film exhibiting different absorption edges could adjust the transmittance of energetic electromagnetic radiation. The variations on absorption edge due to energy band gap were controlled by the absorbed dose.

Irradiation Effect on Ta2O5 Thin Films

Long-term effects of time-dependent solarization behavior on optical density and optical band gap of the gamma and beta irradiated Ta2O5 thin films were investigated to examine the optical aging of films at different absorbed dose levels. Irradiation process caused to induce defect centres. The population inversion of the colour centres was increased by controlling the absorbed dose at certain radiation dose levels. The efficient absorption of photons in tantalum reduced transmittance. The grain boundaries of the Ta2O5 thin film decreased at the end of irradiation process. The average grain boundaries changed after the irradiation process at 4.5 kGy and average grain boundaries decreased from ~ 11.5 to 5.5 μm. The optical fading behavior of induced color centers addressed to the potential opportunities of Ta2O5 thin film by monitoring absorption of photons in optoelectronic technology. Optical fading of the Ta2O5 thin film presented an importance to investigate the material stored ionizing radiation dose in it with the increase of elapsed time after the irradiation treatment.