128 research outputs found
Preparation and Characterization of Injectable Poly (methyl Methacrylate) (pmma) Zirconia Composites
No full textÇalışmanın amacı, üç boyutlu (3B) yazıcı ile biyomateryaller üretmektir. PMMA/Zirkonya biyomateryalleri, ağırlıkça farklı zirkonya tozlarının PMMA solüsyonlarına ısıtma ocağı üzerinde manyetik balık ile 75 ˚C karıştırılması ile üretilmiştir. Hazırlanan malzemeler şırınga ile istenilen şekle sokulmuştur ve farklı sinterleme sıcaklıkları ile sinterlenmiştir. PMMA örneklerinin kimyasal yapı analizi ATR-FTIR ile tayin edilmiştir. Hazırlanan örneklerin morfolojik özellikleri taramalı elektron mikroskobu (SEM) ile incelenmiştir. Kristalinite ve faz değişimleri X-ışını Kırınım (XRD) ile tayin edilmiştir. Mekanik testler ise sıkıştırma dayanımı testleri ile gerçekleştirilmiştir. ATR-FTIR analizi sonuçlarına göre PMMA ~ 70% oranında polimer dönüşümü göstermiştir. SEM görüntülerine göre; porozite, PMMA miktarı ile artma, sinterleme sıcaklığı ile ise azalma göstermiştir. Sinterleme sıcaklığına bağlı olarak tanelerde (grain) topaklanma görülmüştür. XRD sonuçlarına göre, sinterleme sıcaklığındaki artış tetragonal fazın yüzde hacminde düşüşe sebep olmuş; malzemenin kristalit boyutunu ise artırmıştır. Mekanik testler sonucunda ise, sıkıştırma dayanımı; sinterleme sıcaklığı ile birlikte artmış, PMMA miktarı ile azalmıştır. Anahtar kelimeler: Biyomalzemeler, üç boyutlu (3B) baskı, PMMA, ZirkonyaThe purpose of this study is to fabricate 3D printed biomaterials. PMMA/Zirconia biomaterials were prepared by the addition of different percent weight of Zirconia powder to PMMA solution on a hot plate at 75 ˚C with continuous magnetic stirring until the stirrer stopped. The prepared sample was injected by using a syringe to get the desirable shape. Then it was sintered at different sintering temperature. Characterization of synthesized PMMA was performed by ATR-FTIR. Characterization of samples morphology were carried out by Scanning Electron Microscopy (SEM). Crystallinity and phase transformation were investigated by X-ray Diffraction (XRD). The mechanical test was performed by applying compressive strength test. According to ATR-FTIR test, synthesized PMMA showed a degree of conversion ̴ 70%. SEM micrographs showed that porosity increases with PMMA content and decreases with the increase of sintering temperature. Particles size was different, as it refers to grains agglomeration due to sintering temperature. XRD patterns showed that the percentage volume of tetragonal phase decreases with the increase of sintering temperature and crystallite size increases with the sintering temperature. Compressive strength test showed that the compressive strength increases with the increase of sintering temperature and decreases with the increase of PMMA amount. Key words: Biomaterials, 3D Printing, PMMA, Zirconi
Photocatalytic activity of hydroxyapatite-precipitated potassium titanate whiskers
No full textPark, Jongee/0000-0003-1415-6906Photocatalytic properties of hydroxyapatite (HAP)-precipitated multifunctional potassium titanate (KT) whiskers were investigated in terms of the decomposition of methylene blue (MB) in aqueous solution under UV irradiation. Hydroxyapatite was formed on the surface of KT whiskers through a biomimetic process in simulated body fluid (SBF). The SBF used in this investigation had concentrations of calcium and phosphate ions 10 times greater than those of human plasma. Results revealed that hydroxyapatite precipitation enhanced the photocatalytic activity of the KT whiskers. In the case of unreacted KT whisker, complete degradation of methylene blue took 5.5 h, on the other hand degradation time decreased to 3.5 h when the whisker was precipitated with hydroxyapatite. (C) 2009 Elsevier B.V. All rights reserved
Bioactivity of Apatite-Wollastonite Glass-Ceramics Produced by Melting Casting
No full textPark, Jongee/0000-0003-1415-6906; Ozturk, Abdullah/0000-0002-1525-1561; Ozturk, Abdullah/0000-0002-1525-1561Glass-ceramics containing only apatite and wollastonite crystals were produced in the system MgO-CaO-SiO2-P2O5-F by the melt casting process. The bioactivity of the glass-ceramics was determined by immersing the glass-ceramics in a simulated body fluid (SBF) and by assessing the resulting apatite formation on the free surface after various immersion durations. A 12-mu m-thick apatite layer formed on the surface of the glass-ceramic containing only apatite crystals after 20 days immersion in SBF. However, the thickness of the apatite layer formed on the surface of the glass-ceramic containing apatite and wollastonite crystals was 1 mu m. Results have shown that the bioactivity of glass-ceramic depends strongly on the type of crystal(s) developed during the glass-ceramic process and their proportion in the glassy matrix
Influence of Boron And/Or Zirconium Doping on Morphology and Optical Properties of Titania
No full textPark, Jongee/0000-0003-1415-6906; Kapusuz Yavuz, Derya/0000-0002-6935-9762Sol-gel derived B (boron) and Zr (zirconium) doped TiO2 (Titania) nanoparticles were synthesized. Microstructural, photocatalytic and crystallographic properties of the doped particles were investigated. Highest photocatalytic activity was achieved by 10 wt% Zr doping. 5 wt% doping was the optimum value for effective B doping. B ions were found to form oxygen vacancies behaving as interstitial defects whereas Zr ions substituted Ti4+ ions in the lattice.TUBITAK [110M206]Authors specially thank to Scientific and Technological Research Council of Turkey (TUBITAK). The study was supported by the TUBITAK Project: 110M206Conference Proceedings Citation Index - Scienc
Computational Insight of Lithium Adsorption and Intercalation in Bilayer Tic3
No full textPark, Jongee/0000-0003-1415-6906Lithium-ion batteries (LIBs) have gained significant attention owing to their long lifespan. However, these batteries offer unmatched energy storage capacity and suffer from restricted lithium-ion mobility within the electrodes. Here, we employ first-principles calculation to investigate the two-dimensional TiC3 bilayer material. The results exhibit a remarkably high specific capacity of 1277 mAh/g and a low diffusion energy barrier of 0.12 eV. The TiC3 bilayer is anticipated to show high electrical conductivity, maintaining its metallicity due to strong bonding with four Li atoms. Additionally, its high thermal and dynamic stabilities are expected to significantly enhance the battery performance. Notably, the AB stacking bilayer TiC3 experiences a mere 6.01 % increase in volume, considerably smaller compared to the 28 % increase observed in the SiC bilayer. This suggests that TiC3 bilayers remain intact even at the highest concentration of lithium adsorptions. We also explored the solidelectrolyte interface (SEI) formation at the outset of battery operation using reactive force field molecular dynamics simulation. The reactive products of SEI are nicely matched with previous experimental and theoretical findings. All these intriguing properties position the TiC3 bilayer as an exceptionally promising material for use in LIBs.Scientific and Technological Research Council of Turkey (TUBITAK) [123M723]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK, Project no: 123M723)
Two-Dimensional Carbon Rich Titanium Carbide (tic3) as a High-Capacity Anode for Potassium Ion Battery
No full textPark, Jongee/0000-0003-1415-6906In recent years, two-dimensional (2D) materials, particularly MXenes such as titanium carbide, have gained significant interest for energy storage applications. This study explores the use of potassium-adsorbed TiC3 nanosheets as potential anode materials for potassium ion batteries (KIBs), utilizing first-principles calculations. The investigated electronic, mechanical, and thermal properties of TiC3 demonstrate its suitability as an anode material. The incorporation of potassium into the host material enhances electronic conductivity while maintaining a stable layered structure. Our findings reveal promising adsorption behavior of potassium in TiC3, leading to a high theoretical specific capacity of 958 mAh/g, coupled with a low energy barrier of 0.19 eV for potassium migration, which is indicative of superior electrochemical performance. Moreover, despite the high potassium content, the electrode material shows limited volume expansion of 11.3 %, suggesting good cyclability. Additionally, the equilibrium distance between potassium and TiC3, measured at 3.11 & ring;A, exceeds that of lithium and TiC3 (2.56 & ring;A), potentially augmenting the material's flexibility. Consequently, TiC3 emerges as a promising candidate for KIB anode materials.Scientific and Technological Research Council of Turkey (TUBITAK) [123M723]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK, Project no: 123M723)
A Dft Study of Tic3 as Anode Material for Li-Ion Batteries
No full textPark, Jongee/0000-0003-1415-6906Two-dimensional monolayer titanium carbide (TiC3) was used to study as a suitable electrode material for lithium-ion batteries with first principles calculation. The monolayer TiC3 showed excellent structural stability, high mechanical stiffness and good electronic conductance behaviour. The adsorption of Li on the carbon rich composition of titanium carbide monolayer is predicted to be favourable. TiC3 structure has remained the same, preserving its metallicity after Li adsorption with attaining high electrical conductivity during lithiation/delithiation process. Especially, the theoretical specific capacity of TiC3 monolayer is high, up to 1916 mAh/g, which is five times higher than the practical graphite. The low open circuit voltage (0.26 V) and diffusion energy barrier (0.25 eV) are also beneficial for overall performance of LIBs. Importantly, during lithiation the change in area is very small and reaches only 8.1 % for full lithiation indicating that it can avoid the large volume expansion during charge/discharge cycles. Its excellent performance, including high melting temperature, dynamical and mechanical stability, can be credited to the rigidness of the TiC3. Given these advantages, that is, high specific capacity, low Li diffusion energy barrier, low open circuit voltage and high in-plane stiffness, TiC3 monolayer can be a promising anode material for lithium-ion batteries
Mechanical Properties of B<sub>4</Sub>c-sic Composites Fabricated by Hot-Press Sintering
No full textPark, Jongee/0000-0003-1415-6906; So, Sung Min/0000-0002-0185-0520We fabricated boron carbide-silicon carbide (B4C-SiC) composites by hot-press sintering without additives and evaluated the crystal phase, relative density, microstructure, and mechanical properties of the sintered body. When B4C and SiC were uniformly dispersed in the composite, crystal growth was inhibited, and a sintered body with a fine and uniform microstructure, with improved mechanical properties, was fabricated. The relative density of B4C-SiC composites sintered at temperatures lower than 2000 degrees C and 40 MPa of pressure exceeded 99.8%, and the bending strength and Vickers hardness at B4C 50 wt% were 645 MPa and 30.6 GPa, respectively
Boron and zirconium co-doped TiO<sub>2</sub> powders prepared through mechanical ball milling
No full textOzturk, Abdullah/0000-0002-1525-1561; Park, Jongee/0000-0003-1415-6906; Ozturk, Abdullah/0000-0002-1525-1561A titania photocatalyst co-doped with boron and zirconium was prepared by mechanical ball milling. The resulting powder was characterized by XRD, XPS, SEM, and EDS. The photocatalytic performance of the powder was evaluated by degradation of methylene blue (MB) solution under UV illumination. XRD patterns were refined by Rietveld analysis to obtain accurate lattice parameters and positions of the atoms in the crystal structure of the photocatalyst. XRD, XPS, and Rietveld analysis results indicated that mechanical ball milling successfully weaved the dopant elements into the crystal structure and distorted the lattice of TiO2. Also, SEM micrographs confirmed that mechanical ball milling led to a decrease in average particle size of the photocatalyst. Boron and zirconium co-doped TiO2 particles exhibited a better visible light response and photocatalytic activity than those of the mono-element doped TiO2 (i.e. B-TiO2 and Zr-TiO2) and undoped TiO2 particles. The enhanced photocatalytic activity is attributed to the synergistic effects of boron zirconium co-doping and particle size reduction. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.National Boron Research Institute of Turkey [BOREN-2010.C0275]This work was partially supported by the National Boron Research Institute of Turkey, Project number BOREN-2010.C0275
Silver-Loaded Tio<sub>2</Sub> Powders Prepared Through Mechanical Ball Milling
No full textPark, Jongee/0000-0003-1415-6906; Ozturk, Abdullah/0000-0002-1525-1561; Ozturk, Abdullah/0000-0002-1525-1561Silver (Ag) was loaded on TiO2 powders through mechanical ball milling. Ag-loading was accomplished by adding 4.6, 9.2, and 13.8 ml of AgNO3 solution to the TiO2 powders during the milling process. The resulting powder was characterized by XRD, XPS, SEM, and EDS. The photocatalytic activity of the silver-loaded powder was evaluated in terms of the degradation of methyl orange (MO) solution under ultraviolet (UV) illumination. XRD patterns were refined using the Rietveld analysis to determine the lattice parameters. XRD analysis suggested that Ag was loaded on TiO2 powders in the form of AgO. X-ray photoelectron spectroscopy and Rietveld analysis revealed that silver did not dope into the crystal structure of TiO2. SEM investigations confirmed that ball milling caused a decrease in the average particle size of the powders. Silver-loading improved the photocatalytic activity of the TiO2 powders. The TiO2 powder ball milled without Ag-loading degraded 46% of the MO solution whereas the ball milled with 13.8 ml AgNO3 solution degraded 96% of the MO solution under 1 h UV irradiation. Moreover, TiO2 powders gained antibacterial property after Ag-loading. (c) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Scientific and Technological Council of Turkey (TUBITAK) [109M048]Authors gratefully acknowledge the partial financial support of the Scientific and Technological Council of Turkey (TUBITAK) through the Project no. 109M048
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