Soltabayev, Baktiyar; Çağırtekin, Ali Orkun; Mentbayeva, Almagul; Yıldırım, Memet Ali; Acar, Selim

In:ZnO thin films with different indium concentrations (0% In, 1% In, 3% In, 5% In, and 7% In) were synthesized using successive ionic layer adsorption and reaction method. X-ray diffraction (XRD) analysis revealed that all synthesized thin films are well crystallized in the wurtzite phase with the crystallites preferentially oriented toward (002) direction, and demonstarted that crystallite size decreases with In insertion. The energy dispersive X-ray analysis analysis (EDX) confirmed In concentration and the stoichiometric increase in In/ZnO ratio of the synthesized ZnO thin films. The surfaces of all synthesized thin films were analyzed by atomic force microscopy (AFM) in order to understand the effect of indium insertion on the surface morphology. The surface roughness of the films decreased with the increase in In content, likely as a result of the formation of smaller grain size calculated by XRD which was clearly displayed by AFM images. The optical properties of the synthesized thin films were investigated by the absorption coefficient variation. The measured energy bandgap values increased with In insertion and were in a range close to the bandgap of intrinsic ZnO semiconductor. Electrical characterization was achieved using two-contact structure method by DC and AC analyses. The DC study revealed that the measured electrical resistance decreases from 7.25 × 109 Ω to 1.05 × 109 Ω with increasing In concentration from 0% to 7%. The same behavior was also demonstarted using complex AC impedance and modulus analyses of the thin films. Such analyses also revealed that upon indium insertion, the influence of grain boundaries significantly predominates and has a non-Debye type of relaxation. In addition, activation energies were estimated from the impedance and modulus spectra and their values were approximately the same.

ASTAM, Aykut

Phase pure Cu2SnSe3 thin films were successfully obtained on glass substrates by annealing of successive ionic layer adsorption and reaction (SILAR) deposited thin films at 623 K for an hour in selenium atmosphere. Structural, morphological, compositional, and optical properties of films were investigated, before and after annealing, via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results showed that films were polycrystalline nature with cubic structure, the crystallinity was improved with annealing and the secondary phase of SnSe disappeared as well. SEM images revealed existence of the relatively big islands, which were formed overlapping large number of small grains, was observed on the surfaces. The images also showed a considerable change in the shape of the grains with annealing. EDAX measurements revealed that chemical composition of the annealed film was very close to the ideal value 2:1:3. The results of Raman measurement confirmed the formation of Cu2SnSe3 and disappearance of the secondary phase of SnSe after annealing. The optical absorption studies showed that the films have direct transitions with band gap energies of 1.38 eV and 1.34 eV before and after annealing, respectively.

Akaltun, Yunus

CuO thin films were synthesised on glass substrates at room temperature using successive ionic layer adsorption and reaction (SILAR) method. The effect of film thickness on characteristic parameters such as the structural, morphological and optical properties of the films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all of the films exhibited polycrystalline structure with monoclinic phases and covered the glass substrates well. The crystalline and morphology of the films improved with increasing film thickness. The optical band gap decreased from 2.03 to 1.79 eV depending on the film thickness. The refractive index (n), electron effective mass (me∗/mo) and static and frequency dielectric constants (ϵo, ϵ∞) were determined using the energy band gap values.

Demirci, Ebru Emine; Arslan, Ersin; Ezirmik, Kadri Vefa; Baran, Özlem; Totik, Yaşar; Efeoglu, Ihsan

Micro arc oxidation (MAO) is an effective technique to improve the surface properties of light materials by forming ceramic films on the surface. A number of studies have been carried out regarding depositing on Mg and Mg alloys. However, only a few have focused on wear, corrosion or tribocorrosion properties. In this study, the MAO process was carried out on AZ91 Mg alloy in two different electrolyte solutions; namely phosphate-silicate and potassium stannate. The microstructures, morphology and crystallographic structure were analysed using SEM and XRD. The wear, corrosion and tribocorrosion properties of the coatings were investigated using the pin-on-disc wear test, potentiodynamic polarisation test and combining the tribocorrosion test unit, respectively. The results showed that the type of solution has an important role on the wear, corrosion and tribocorrosion resistance of the MAO coating.