Aydin, Handan; Sait Kanca, M.; Kök, Mediha; Taşgin, Yahya; Tatar, Beyhan

Thin film technology aims to improve and develop the properties of materials by coating technology. In this study, thin films consisting of rare earth element and selenium semiconductor material, which have recently been preferred in technological applications due to their important properties, are examined. Selenium thin films doped with Ho2O3 and Dy2O3 rare earth oxides (REO) were fabricated on glass substrate by thermal evaporation method. The surface morphology and optical properties of the thin films were investigated. As a result of surface morphology examinations, it was determined that homogeneous thin films were obtained and the thickness of the thin films varied between 20 and 30 μm. In addition, the roughness value of the glass substrate decreased as a result of coating with doped selenium thin film. The band energy value obtained by UV-VIS measurements decreased compared to glass and was close to the selenium element value. In the comparison between selenium coatings doped with Ho2O3 and Dy2O3, a notable reduction in the Eg value was observed specifically in the Ho2O3 doped coatings.

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Tatar, Cengiz; Kök, Mediha; Kanca, M Sait; Tatar, Beyhan

Shape memory alloys are exposed to high temperatures to improve their properties and functionality. Through this process, oxidation inevitably occurs due to the presence of oxygen in the environment, which interacts with the alloying elements. Oxidation adversely affects the hardness of alloys, leading to a decline in their overall quality. In this study, the oxidation behavior parameters of FeMnSi and FeMnSi-Cr alloys and the oxide layers formed during this process were investigated in Fe-based alloys with high usage potential. Both non-isothermal and isothermal oxidation processes were applied to alloys and the oxidation parameters were determined. Subsequently, the changes in the crystal structure, microstructure, and magnetic properties of the alloys subjected to isothermal oxidation at 400-500-600-700-800 °C were investigated. It was found that the oxidation behavior of both alloys intensified with rising oxidation temperatures, as evidenced by crystal structure and microstructural analyses, which indicated deeper penetration into the alloys at elevated temperatures. Furthermore, an increase in magnetization values was noted alongside the oxidation process. A comparison of the oxidation characteristics between FeMnSi and FeMnSi-Cr alloys revealed that the oxidation parameters for the chromium doped FeMnSi alloy were comparatively lower.

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Pekdemir, Mustafa Ersin; Kök, Mediha; Kanca, Muhammed Sait; Özen Öner, Ecem; Pekdemir, Sibel; Inci, Şule; Kirbağ, Sevda; Tatar, Beyhan

Recently, there has been a great demand for boron-containing compounds (BCCs) with unique biological properties. The demand for the use of these compounds not alone but as additives in composite materials is increasing day by day. In this study, the effect of adding B2O3 compound to the blend of PLA and PEG polymers, which is an important biocompatible shape memory polymer, was investigated. In order to examine the effect of increasing B2O3 additive on the thermal properties of PLA-PEG blend, it was determined by using a Differential Scanning Calorimetry (DSC) and thermogravimetric analyzer (TGA), and it was seen that while the melting temperature of PEG decreased, the melting temperature of PLA increased. In addition, when the thermal stability of the composites was examined, increasing of thermal stability was observed with the addition of B2O3 and a three-step degradation occurred. It was determined that the B2O3/PLA-PEG composite was homogeneous by taking X-ray measurements and SEM measurements. The antimicrobial property of the PLA-PEG blend improved with the increasing B2O3 contribution were observed from the antimicrobial activity measurements of the composite against 4 different bacteria. However, it was determined that the PLA-PEG blend preserved its shape memory effect with increasing diboron trioxide contribution.

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