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DEMİRCİ, SELİM

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DEMİRCİ

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SELİM

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2017 - 201912020 - 20223
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    PublicationOpen Access
    Production of Zn-doped TiO2 film with enhanced photocatalytic activity
    (2022-12-01) DEMİRCİ, SELİM; DİKİCİ T., YILMAZ O., Akalin A., DEMİRCİ S., GÜLTEKİN S., YILDIRIM S., YURDDAŞKAL M.
    In this study, zinc (Zn)-doped titanium dioxide (TiO2) films were prepared using the two steps: anodic oxidation method and heat treatment process. The crystal structure, morphology and elemental composition of the Zn-doped TiO2 films were investigated. These films were characterized by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the TiO2 films with clear, uniform and short nanopores had a high surface area and high degree of crystallinity. The results showed that the asanodized TiO2 film was successfully obtained as anatase phase at 450 degrees C. The results of XPS analysis confirmed the presence of Zn in the lattice of TiO2 as dopant, and thermal diffusion technique was successfully done as doping method. The photocatalytic performances of the Zn-doped TiO2 films were evaluated in terms of their photodegradation rate of methylene blue (MB) in an aqueous solution under UV light irradiation. The results revealed that the Zn-doped TiO2 film had a higher photocatalytic activity in comparison with the undoped sample. This study inspired that Zn-doped TiO2 films are a great potential material to treat wastewater in industrial field.
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    PublicationOpen Access
    Production, characterization, and luminescent properties of Eu3+ doped yttrium niobate-tantalate films
    (SPRINGEROPEN, 2017-03) DEMİRCİ, SELİM; Yildirim, Serdar; Demirci, Selim; Ertekin, Kadriye; Celik, Erdal; Alicikus, Zumre Arican
    Monoclinic yttrium tantalate (M'-YTaO4, M '-YTO), and two different kinds of yttrium niobium-tantalate (M '-YTa0.85Nb0.15O4 (M '-YTNO) and Eu3+ doped M '-YTa0.85Nb0.15O4 (M '-YTNO:Eu3+)) were produced by sol-gel method and grown on single crystalline Si (100) substrate by spin coating approach. Structural properties and thermal behaviours of the films were characterized by means of X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and thermogravimetry and differential thermal analysis (TG-DTA). Systematic Steady-state photoluminescence and lifetime measurements in a series of yttrium niobium-tantalate with varying amounts of Eu3+ were presented. The photoluminescence spectra of the films exhibited strong blue (380-400 nm) and red (614 nm) emissions upon ultraviolet excitation. Emission intensities were strongly dependent on the host lattice composition and film morphology. 1.5% Eu3+ doped films exhibited the brightest luminescence and long lifetime extending to 1.22 ms when excited at 254 nm. To the best of our knowledge, this is the first attempt in the production of M '-YTO, M '-YTNO, and M '-YTNO:Eu3+ films on single crystalline Si (100) substrate via sol-gel spin coating.
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    PublicationOpen Access
    Investigation of surface-modified EBM printed Ti-6Al-4V alloys for biomedical applications
    (2022-11-01) DEMİRCİ, SELİM; TÜNÇAY, MEHMET MASUM; GÜLLÜOĞLU, ARİF NİHAT; DEMİRCİ S., DİKİCİ T., TÜNÇAY M. M. , DALMIŞ R., KAYA N., Kanbur K., Sargin F., GÜLLÜOĞLU A. N.
    This work aimed to comprehensively assess the influence of various surface modifications on the formation of apatite ability for EBM Ti-6Al-4V alloy. Sandblasting (S), acid-etching (E), sandblasting and acid-etching (SE), anodization (NA), micro-arc oxidations in 1 M H2SO4 solution (SM) and 1 M H3PO4 solution (PM) methods were applied to modify electron beam melted (EBM) Ti-6Al-4V surface. The alpha/alpha\"-Ti structures and TiO2 phases were detected by XRD. The surface roughness (Ra) values ranged from 0.25 mu m and 2.86 mu m. The wettability of samples was between around 25 degrees and 104 degrees The SM sample possessed the lowest contact angle. In vitro tests were employed in the simulated body fluid (SBF) solution for 28 days. The samples with different surface textures demonstrated bioactive behaviors. In vitro test results showed that apatite layers formed on the surfaces. The SM sample exhibited good apatite formation ability when the Ca/P ratios were considered. The apatite formation for the SM sample might derive from high roughness, low contact angle value, the existence of Ti-OH groups, and anatase and rutile phases. The SM can be implemented to boost bioactivity on EBM Ti-6Al-4V alloys.
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    PublicationOpen Access
    A study of heating rate effect on the photocatalytic performances of ZnO powders prepared by sol-gel route: Their kinetic and thermodynamic studies
    (ELSEVIER, 2020-03) TÜNÇAY, MEHMET MASUM; Demirci, Selim; Dikici, Tuncay; Tuncay, Mehmet Masum; Kaya, Nusret
    In this work, ZnO particles were fabricated by sol-gel method at different heating rate at 500 degrees C for 2 h. The ZnO powders were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and photoluminescence, respectively. The effect of heating rate on photocatalytic activities of ZnO particles was evaluated by degradation of methylene blue (MB). The non-isothermal kinetics and thermodynamic properties were also estimated. The XRD results showed that ZnO had hexagonal wurtzite structure. The different heating rate didn't influence the surface morphology of ZnO powders. It was observed that the heating rate had a profound effect on reduction of band gap and photocatalytic performances. The band gap of the ZnO particles varied from 3.10 to 3.17. The ZnO sample prepared at 1 degrees C/min exhibited the highest photocatalytic activity. Its relative photocatalytic degradation rate and kinetic constant were 92.7% and 1.069x10(-2) min(-1), respectively. The results might be ascribed to low bulk vacancies, high surface oxygen vacancies and narrow band gap energy. Also, ZnO photocatalysts showed good stability after four sequence tests. This study provides a new strategy to improve the photocatalytic performances of ZnO photocatalyst for the degradation of organic contaminant.