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DEMİRCİ, SELİM

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DEMİRCİ

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SELİM

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2017 - 201912020 - 20221
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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.