Park, Jongee
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Name Variants
Jongee Park
P.,Jongee
P., Jongee
J.,Park
Park J.
Park, Jongee
Park,J.
J., Park
Park,Jongee
Jongee, Park
P.,Jongee
P., Jongee
J.,Park
Park J.
Park, Jongee
Park,J.
J., Park
Park,Jongee
Jongee, Park
Job Title
Profesör Doktor
Email Address
jongee.park@atilim.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
56
Articles
41
Citation Count
578
Supervised Theses
3
54 results
Scholarly Output Search Results
Now showing 1 - 10 of 54
Conference Object Citation Count: 0Production of potassium titanate whisker reinforced dental composites(2014) Kapusuz,D.; Park,J.; Ozturk,A.; Metallurgical and Materials Engineering; English Translation and InterpretationPotassium titanate (K2O.nTiO2) whiskers (KTWs) were produced by sol-gel method and embedded into UDMA-TEGDMA resins to produce KTW reinforced composites that could be used for both anterior and posterior fillings. The effect Ti/K molar ratio on the chemical, structural and functional properties of the KTWs was investigated using XRD, HR-TEM, and BET analysis. Morphology and the surface properties of the KTWs rely on the Ti/K ratio. However, HR-TEM studies clarified that the KTWs grow along [110] axis regardless of Ti/K ratio. BET analysis revealed the presence of slit shaped meso-pores in the KTWs. The KTW reinforced composites were produced by mixing UDMA-TEGDMA resins at molar compositions of 30-70, 70-30, and 50-50 wt%, and by embedding 5 wt% KTW homogeneously into the mixtures. Photocatalytic activity of the KTWs and the KTW reinforced composites were evaluated through Methylene Blue degradation test. Photocatalytic activity of the composites decreased as Ti/K ratio is increased although it showed a tendency to increase in the KTWs with increasing Ti/K ratio. Meanwhile, the photocatalytic activity of the composites was superior to unreinforced resin mixtures. Mechanical properties namely, nanoindentation hardness and wear-rate of the bulk polymers enhanced significantly by KTW reinforcement.Article Citation Count: 0TiO2 FILMS WITH VARIOUS CRYSTAL STRUCTURES FOR SINGLE AND BILAYER PHOTOANODES OF DYE-SENSITIZED SOLAR CELLS(2018) Erdoğan, Nursev; Park, Jongee; Öztürk, Abdullah; Metallurgical and Materials EngineeringPhase pure and composite TiO2 nanopowders exhibiting various crystal structures (anatase, rutile and brookite) are used asphotoanode in dye-sensitized solar cells. The nanopowders are deposited in paste form onto a conducting oxide glass usingdoctor blade method in single layer and bilayers. The highest solar efficiency achieved by the single layer photoanode composedof > 99 wt % anatase crystals was 2.86 %. The solar efficiency of 4.93 % has been harvested via bilayer photoanode built byapplying a layer consisting 55 wt % anatase and 45 wt % rutile phase nanoparticles on top of the layer composed of a mixtureof > 99 wt % anatase crystals. The improved photovoltaic performance is attributed to anatase dominated bottom layer whichfacilitates electron charge generation with high surface area and charge transport by proper crystal structure as well assynergistic effect of binary phase content of the photoanodes. The porous structure of top layer enhances diffusion of theI−/I3−electrolyte in the bilayer TiO2 photoanode.Article Citation Count: 11Effects of fluorination and thermal shock on the photocatalytic activity of Bi2O3 nanopowders(Elsevier, 2021) Bouziani, Asmae; Park, Jongee; Ozturk, Abdullah; Metallurgical and Materials EngineeringFluorinated Bi2O3 (F-Bi2O3) nanopowder was prepared via fluorination followed by thermal shock of alpha-Bi2O3 nanopowder. The XRD, FTIR, SEM, and DRS characterization techniques were employed to investigate the effects of fluorine (F) insertion into the alpha-Bi2O3 host and the thermal shock from different temperatures. The crystal structure, optical and photocatalytic properties of the F-Bi2O3 nanopowders prepared were researched. The XRD results confirmed the substitution of O2- with F-. The FTIR results revealed that the coordination of Bi atoms changed upon F- substitution. The incorporation of F into the alpha-Bi2O3 host and thermal shock did not influence the morphology but modified the band structure of alpha-Bi2O3, leading to a red-shift in the optical absorption edge. Also, the bandgap narrowed from 2.8 eV to 2.6 eV. The density functional theory calculation proved that the F 2p orbitals were positioned in the valence band (VB), resulting in broader and more spread bands for F-Bi2O3. The results suggested that the photoexcited charge carrier mobility in the valence band (VB) and conduction band (CB) are enhanced upon F insertion into alpha-Bi2O3. The photocatalytic efficiency of the synthesized nanopowders was assessed by the degradation of Bromocresol Green (BG) under visible light illumination. Photocatalytic activity improved upon fluorination. The F-Bi2O3 nanopowders thermally shocked from higher temperatures showed negligible photocatalytic performance. The best photocatalytic performance of 70% BG degradation was realized after 180 min visible irradiation for the F-Bi2O3 nanopowder thermal shocked from 500 degrees C.Article Citation Count: 40Silver-loaded TiO2 powders prepared through mechanical ball milling(Elsevier Sci Ltd, 2013) Aysin, Basak; Ozturk, Abdullah; Park, Jongee; Metallurgical and Materials EngineeringSilver (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.Article Citation Count: 5Preparation and photocatalytic activity of apatite-precipitated TiO2(2011) Soysal,K.; Park,J.; You,S.H.; Shin,D.W.; Bae,W.T.; Ozturk,A.; Metallurgical and Materials Engineering; English Translation and InterpretationApatite was precipitated on the surface of titanium dioxide (TiO2) powder by a biomimetic process. The precipitation was accomplished by immersing TiO2 powder in simulated body fluid (SBF) for 1, 3, 6, 12 and 24 h. Photocatalytic activity of the apatite-precipitated TiO2 (HAp-TiO2) powders was investigated to assess the decomposition of methylene blue (MB) in aqueous solution and the removal of acetaldehyde gas under UV irradiation. Hydroxyapatite precipitation enhanced the photocatalytic activity of the TiO2 powder. The time required for the complete degradation of MB decreased from 3.5 to 2 h with the immersion of TiO2 powders in SBF for 3 h. In terms of acetaldehyde gas decomposition, less than 1 h was sufficient to achieve complete removal for HAp-TiO2 powder but at least 2 h were required for the bare TiO2 powder. HAp-TiO2 powders could therefore be a promising candidate photocatalyst for environmental purification.Article Citation Count: 8Synthesis and characterization of hydrothermally grown potassium titanate nanowires(Hanyang University, 2015) Kapusuz,D.; Eren Kalay,Y.; Park,J.; Ozturk,A.; Metallurgical and Materials Engineering; English Translation and InterpretationPotassium titanate (KT) nanowires were synthesized by a one-step hydrothermal reaction between TiO2 and aqueous KOH solution. The effects of KOH concentration and reaction time on hydrothermal formation and KT nanowire growth were investigated. The nanowire growth mechanism was elucidated using a combined study of powder X-ray diffraction, and scanning and transmission electron microscopy. The results revealed that hydrothermal growth was initiated by the formation of amorphous-like Ti-O-K sheets in anatase. Increasing hydrothermal reaction time caused the transformation of anatase to Ti-O-K sheets, from which potassium hexa-titanate (K2Ti6O13) nuclei formed and grew to establish one-dimensional morphology through preferential growth along the b-axis. It was revealed that the hydrothermal reactions followed a quite different mechanism than the well-known calcination route. Potassium tetra-titanate (K2Ti4O9) crystals formed in the amorphous region using the hexa-titanate phase as a nucleation site for heterogeneous crystallization. Increasing the KOH concentration in the solution accelerated the hydrothermal reaction rate. © 2015, Hanyang University. All rights reserved.Article Citation Count: 2BIOACTIVITY OF APATITE-WOLLASTONITE GLASS-CERAMICS PRODUCED BY MELTING CASTING(World Scientific Publ Co Pte Ltd, 2013) Park, Jongee; Ozturk, Abdullah; Metallurgical and Materials EngineeringGlass-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.Article Citation Count: 12Tribological behavior of alumina-added apatite-wollastonite glass-ceramics in simulated body fluid(Elsevier Science Sa, 2010) Park, Jongee; You, Sang-Hee; Shin, Dong-Woo; Ozturk, Abdullah; Metallurgical and Materials EngineeringTribological properties of an alumina-added apatite-wollastonite glass-ceramic produced by controlled heat treatment of a glass in the system MgO-CaO-SiO(2)-P(2)O(5)-Al(2)O(3) have been evaluated and compared with those of selected commercial dental ceramics, Duceragold and IPS Empress. Tribological tests were performed in dry condition and in simulated body fluid (SBF) using a pin-on-disk apparatus. The friction coefficient and specific wear rate of the tested materials were measured in dry and in artificial saliva (simulated body fluid: SBF) in order to elucidate the appropriateness of the alumina-added apatite-wollastonite (A-W) glass-ceramic for dental applications. Wear rate of the materials investigated varied from 0.96 x 10(-4) mm(3) N(-1) m to 41.37 x 10(-4) mm(3) N(-1) m depending on the bioenvironmental test conditions. The results of this study revealed that the alumina-added A-W glass-ceramic becomes more wear resistant as sintering temperature is increased and exhibits tribological properties similar to those of the commercial dental materials investigated. (C) 2010 Elsevier B.V. All rights reserved.Article Citation Count: 17Synthesis and enhanced photocatalytic activity of nitrogen-doped triphasic TiO2 nanoparticles(Elsevier Science Sa, 2019) Erdogan, Nursev; Bouziani, Asmae; Park, Jongee; Micusik, Matej; Kim, Soo Young; Majkova, Eva; Ozturk, Abdullah; Metallurgical and Materials EngineeringTiO2 nanoparticles of the single anatase phase, binary anatase-brookite phases, and ternary anatase-brookite-rutile phases were synthesized using an HNO3-catalyzed hydrothermal process. The types and amounts of phases varied depending on the hydrothermal synthesis conditions. The results revealed that N dissolves in different amounts and chemical states, depending on the phases present and their proportions in the nano particles. Brookite and rutile nanoparticles oriented through one direction were found to be crystallized by the surface transformation from anatase. Photocatalytic activity tests, evaluated by degradation of methylene blue (MB) under ultraviolet (UV) and visible light illumination, revealed that the N-doped TiO2 nanoparticles containing a ternary-phase mixture had the best photocatalytic activity. The MB degradation of the visible light-active nanoparticles was three times better than that of a commercially available well-known TiO2 powder, P25 under UV illumination. The enhanced photoactivity was attributed to the following: i) a high surface area, ii) suppression of the recombination of electron-hole pairs with ternary-phase mixture crystallized in heterojunctions, iii) larger anatase phase content, and iv) narrower band gap and facilitation of charge separation by dissolved N atoms.Article Citation Count: 29Boron and zirconium co-doped TiO2 powders prepared through mechanical ball milling(Elsevier Sci Ltd, 2013) Tokmakci, Tolga; Ozturk, Abdullah; Park, Jongee; Metallurgical and Materials EngineeringA 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.
