Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Makale Koleksiyonu
Bu koleksiyon için kalıcı URI
Güncel Gönderiler
Öğe İnsight into the photoluminescence of ba2cd(bo3)2: re3+ (re = dy, tb) phosphors(Springer, 2025) Toreli, S. B; Kafadar, V. E.; Emen, F. M.; Özturk, Esra; Altınkaya, RDy3+ and Tb3+ ions doped Ba2Cd(BO3)2 phosphors with varying concentrations (2, 3, 4, 5, 6 mol%) were produced via the solid-state synthesis method in air. The as-synthesized phosphors were characterized. The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Dy3+ ions reveal four distinct emission bands in the blue, yellow, and red regions, with the 575 nm emission band (4F9/2 -> 6H13/2, electric dipole transition) exhibiting a notably higher intensity than the 481 nm band (4F9/2 -> 6H15/2, magnetic dipole transition). The optimal Dy3+ doping concentration was identified as 5 mol%, beyond which concentration quenching effects became apparent. Additionally, excitation and emission spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Tb3+ ions demonstrate efficient energy absorption at approximately 225 nm, with characteristic emission bands observed at 415, 436, 488, 544, 586, and 621 nm, corresponding to the 5D3 -> 7F5, 5D3 -> 7F4, 5D4 -> 7F6, 5D4 -> 7F5, 5D4 -> 7F4, and 5D4 -> 7F3 transitions, respectively. The ideal concentrations for Dy3+ (5 mol%) and Tb3+ (6 mol%) in Ba2Cd(BO3)2 are identified at x = 0.3717, y = 0.4064, and x = 0.2902, y = 0.5344, respectively, as per the Commission Internationale de l'Eclairage (CIE) color spectrum, positioning Dy3+-doped phosphors within the yellow spectrum and Tb3+-doped phosphors within the green spectrum. These phosphors exhibit vibrant yellow and green luminescence, demonstrating their suitability as candidates for applications in these hues. They can be employed when stimulated by near-UV, UV, and blue laser diodes for WLEDs.Öğe İnsight into the photoluminescence of ba2cd(bo3)2: re3+ (re = dy, tb) phosphors(Springer, 2025) Toreli, S. B.; Kafadar, V. E.; Emen, F. M.; Öztürk, Esra; Altınkaya, R.Dy3+ and Tb3+ ions doped Ba2Cd(BO3)2 phosphors with varying concentrations (2, 3, 4, 5, 6 mol%) were produced via the solid-state synthesis method in air. The as-synthesized phosphors were characterized. The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Dy3+ ions reveal four distinct emission bands in the blue, yellow, and red regions, with the 575 nm emission band (4F9/2 -> 6H13/2, electric dipole transition) exhibiting a notably higher intensity than the 481 nm band (4F9/2 -> 6H15/2, magnetic dipole transition). The optimal Dy3+ doping concentration was identified as 5 mol%, beyond which concentration quenching effects became apparent. Additionally, excitation and emission spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Tb3+ ions demonstrate efficient energy absorption at approximately 225 nm, with characteristic emission bands observed at 415, 436, 488, 544, 586, and 621 nm, corresponding to the 5D3 -> 7F5, 5D3 -> 7F4, 5D4 -> 7F6, 5D4 -> 7F5, 5D4 -> 7F4, and 5D4 -> 7F3 transitions, respectively. The ideal concentrations for Dy3+ (5 mol%) and Tb3+ (6 mol%) in Ba2Cd(BO3)2 are identified at x = 0.3717, y = 0.4064, and x = 0.2902, y = 0.5344, respectively, as per the Commission Internationale de l'Eclairage (CIE) color spectrum, positioning Dy3+-doped phosphors within the yellow spectrum and Tb3+-doped phosphors within the green spectrum. These phosphors exhibit vibrant yellow and green luminescence, demonstrating their suitability as candidates for applications in these hues. They can be employed when stimulated by near-UV, UV, and blue laser diodes for WLEDs.Öğe Eco-friendly lead-free metal halide perovskites: progress and prospects in multifunctional applications(Elsevier B.V., 2025) Mukhtar, Maria; Goud, Burragoni Sravanthi; Ali, Zeeshan; Shaid, Muhammad Waleed; Naz, Bushra; Ain, Qurat Ul; Assiri, Mohammed A.; Sönmezoğlu, Savaş; Rajpar, Altaf Hussain; Kim, Jae Hong; Aftab, SikandarRecently, metal halide perovskites have engrossed a lot of attraction in the field of developing optoelectronic technologies due to their special optical-electronic characteristics. The toxicity of lead (Pb) based perovskites has developed a major obstacle that restricts their widespread use, despite the fact that they seem to be rising stars in optoelectronic devices. To overcome this hurdle, Pb-free substitutive perovskites have earned growing interest because of their theoretically remarkable environment friendly optoelectronic properties besides compromising stability and enactment. They are not only gaining attention for applications in solar devices but their properties make them an ideal candidate for many other demanding applications. To elucidate the applicability of eco-friendly perovskites in numerous applications, the present article provides an extensive overview of current developments in eco-friendly perovskites in a range of contemporary applications outside of photovoltaics. An overview of these Pb-free perovskites' crystal structure and chemical variety is initially presented. For a number of purposes like artificial synapses, light-emitting diodes, resistive switching memory, photodetectors, and displays, a methodical review of lead-free perovskites is presented in this article. The demonstration of photocatalysis, radiation detection, imaging, sensors, thermoelectric and piezoelectric energy harvesting, and more is crucial. Pb-free perovskite future development prospects and challenges in the aforementioned fields are described, that are thought to be essential for accelerating the profitable adoption of above-mentioned cutting-edge technologies. © 2025 Elsevier B.V.Öğe Copper extraction from deep eutectic solvent as atacamite by hydrolysis method(Konya Teknik Üniv, 2025) Topçu, Mehmet AliDeep eutectic solvents (DESs) have garnered as promising alternatives to conventional solvents for metal extraction due to their facile synthesis, high chloride concentration, non-aqueous nature, and low cost. This work explores a green route for ultrafast extraction of atacamite [Cu2Cl(OH)3] from a deep eutectic solvent at room temperature in a short time using copper (II) sulfate pentahydrate as a precursor. The phase, chemical, morphological, and structural properties of the extracted atacamite were investigated using XRD, Rietveld method, SEM-EDX, and FTIR techniques. As a result of XRD analysis, it was determined that the atacamite with an average diameter of 85.59 mu m has an orthorhombic crystal structure. Also, it was determined that the crystal structure parameters obtained from XRD and the theoretical calculations of these values were in good agreement according to the Rietveld refinement. SEM/EDX analysis showed that the extracted atacamite particles exhibited heterogeneity in terms of size and morphology, while elemental composition was found to be homogeneous throughout the particles. UV-Vis analysis and theoretical calculations, the optical band of atacamite particles was found as 2.72 eV. Also, this study demonstrates that the hydrolysis method can serve as an efficient, low-energy pathway for the recovery of metals from DESs, highlighting its potential as a novel approach in copper metallurgy.Öğe Photoluminescence and thermoluminescence studies of beta-ırradiated ba3cdsi2o8:tb3+ phosphor for led and dosimetry applications(John Wiley and Sons Ltd, 2025) Başaran, Büşra Yazıcı; Kafadar, Vural Emir; Emen, Fatih Mehmet; Öztürk, Esra; Karaçolak, Ali İhsanThe present work reports the preparation, characterization, and photoluminescence (PL) and thermoluminescence (TL) responses of Tb3+-doped Ba₃CdSi₂O₈ phosphors. X-ray diffraction analysis confirmed the consistency of the Tb3+-doped Ba₃CdSi₂O₈ samples with the PDF 00-028-0128 card structure. The TL glow curve of the material was examined at different dopant concentrations after irradiation with a 90Sr/90Y beta source. Among the samples, Ba₃CdSi₂O₈: 5% Tb3+ exhibited the highest TL intensity compared with the other concentrations. The glow curve deconvolution method was used to determine the number of peaks, trap structure, and kinetic parameters within the TL glow curve, yielding a figure of merit (FOM) value of 1.11. The PL spectra show that the 2.0%, 3.0%, 4.0%, 5.0%, and 6.0% mole Tb3+-doped Ba₃Cd (SiO₄)₂ phosphors capture excitation energy through the 4f-5d transitions of Tb3+ ions and emit light at 417, 440, 492, 552, 589, and 628 nm, corresponding to the 5D₃–7F₅, 5D₃–7F₄, 5D₄–7F₆, 5D₄–7F₅, 5D₄–7F₄, and 5D₄–7F₃ transitions, respectively. © 2025 The Author(s). Luminescence published by John Wiley & Sons Ltd.Öğe Defect passivation and crystallization management enabled by thulium dopant as b-site cation for highly stable and efficiency fully inorganic perovskite solar cells with over 17% efficiency(Elsevier B.V., 2025) Camızcı, Ebubekir; Dilci, Ibrahimhan; Xiao, Zhengguo; Sönmezoğlu, SavaşDespite their outstanding thermal stability and optimal band gap for tandem devices, the development of high-performance CsPbI2Br-based inorganic perovskite solar cells is considerably hampered by defect-induced nonradiative recombination and halide ion migration. Herein, we have developed a series of CsPbI2Br inorganic perovskite materials modified by incorporation of thulium (Tm3+) ions as B-site heterovalent dopants and explored their favourable impacts on the photovoltaic and stability performance of fully inorganic perovskite solar cells (FTO/SnO2/CsPb1-xTmxI2Br/CuSCN/r-GO/Au) for the first time. The champion solar cell achieves an impressive efficiency exceeding 17 %, with less degradation (<5%) after 400 h of operational stability and ∼30 % after 320 h of shelf stability owing to suppression of nonradiative recombination of carriers and inhibition of halide ion migration by controlling crystallization and phase stabilization. Overall, Tm3+ ions do not play a role only elimination of ion migration and defects in perovskite film but also protects perovskite layer from moisture and continuous light illumination in fully inorganic perovskite solar cells. © 2025 Elsevier B.V.Öğe Fabrication and optical characterization of V-shaped micro/nano-grooves on indium phosphide surface through double cell electrochemical etching(Springer, 2025) Açıkgöz, Sabriye; Yungevis, Hasan; Tor, NeslihanA versatile and simple method of fabricating micro and nano-grooves on the indium phosphide (InP) semiconductor surface using a double-cell electrochemical etching process is presented in this work. The formation mechanism of the groove structures is thoroughly investigated as a function of different etching parameters, including varying acid concentration, current density, and etching time. The surface morphologies and chemical compositions of the grooves are analyzed using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). It has been observed that electrochemical etching using HCl-based etchants leads to the spontaneous formation of micro and nano-sized grooves on certain side facets of patterned structures, depending on the etching parameters. At high acid concentration, micro-grooves with a lateral length of 980 nm are formed by applying a low current density of 30 mA/cm2 for 6 min. On the other hand, it is revealed that the applied current density needs to be increased to 50 mA/cm2 to obtain a regular grooved InP surface at low acid concentration. Tailoring the etching parameters results in much smaller structures with novel nano-sized features. The impact of morphology on the optical and carrier recombination properties is comprehensively investigated using a steady state photoluminescence (PL) spectrometer and a time-resolved fluorescence lifetime imaging microscope (FLIM). At room temperature, the nano-grooved InP surface exhibits a well-defined, strong emission peak at 920 nm and a carrier recombination lifetime of 6.06 ns. Patterning semiconductor micro/nanostructures with precisely controlled geometries offers a promising opportunity to enhance the performance of optoelectronic devices.Öğe Enhanced photocatalytic hydrogen evolution via sic loaded ceo2 nanofiber composite(Elsevier B.V., 2025) Genç, Münevver Tuna; Sarılmaz, Adem; Aslan, Emre; Özel, Faruk; Patir, İmren HatayCeO2 is a significant material in the photocatalytic hydrogen evolution reactions due to the high creating ability of oxygen vacancies, high chemical stability and excellent redox properties. However, the wide band gap of CeO2 limits the visible light absorption. In this study, SiC loaded to CeO2 nanofiber catalyst by electrospinning methods to improve the light absorption efficiency and increase the active surface area result in enhanced photocatalytic performance. In the photocatalytic hydrogen evolution reactions medium, which contain eosin Y dye and triethanolamine as a photosensitizer and an electron donor, respectively. The addition of SiC to CeO2 improve the visible light absorption rate, electron transfer efficiency. The hydrogen production rate of CeO2/SiC nanofiber catalyst reaches to 5208 μmol g−1 under visible light irradiation, it is approximately 13- and 2-times higher than SiC and CeO2 nanofiber, respectively. Furthermore, CeO2/SiC nanofiber catalyst maintain more than half of it is photocatalytic activity after 3 cycles of reactions. Therefore, the CeO2/SiC nanofiber catalyst will provide innovative approaches to achieve efficient photocatalytic water splitting in the future, enabling the development of catalytic studies. © 2025Öğe A New Promising Silicate-Based Phosphor for Red Light and White Light Emitting Devices(New York : Plenum Press, c1991-, 2025) Başaran, Büşra Yazıcı; Kafadar, Vural Emir; Emen, Fatih Mehmet; Öztürk, Esra; Karaçolak, Ali İhsanThe aim of this study is to investigate the structure, particle morphology, photoluminescence, and chemical composition of materials for application in light-emitting devices. The present work primarily focuses on the synthesis and characterization of Ba₃CdSi₂O₈:RE (RE: Ce³⁺, Eu³⁺, and Dy³⁺) phosphors via the solid-state reaction method. XRD and FT-IR techniques were used to characterize the phosphors. The XRD patterns of the phosphors reveal that the peaks match those of the Ba₃Cd(SiO₄)₂ host material (PDF Card number: 00-028-0128), with no impurity peaks observed. The photoluminescence (PL) emission spectra of Ba₃CdSi₂O₈:RE (RE: Ce³⁺, Eu³⁺, and Dy³⁺) phosphors were investigated in detail. Ba₃CdSi₂O₈:Dy³⁺ phosphors show four emission bands in the blue (450-510 nm), yellow (550-600 nm), red (640-700 nm), and deep red (740-770 nm) regions. Ce³⁺-doped Ba₃CdSi₂O₈ phosphors show a broad emission band from 575 nm to 700 nm, with a maximum around 594 nm, which is assigned to the 5d-4f transition of Ce³⁺ ions. Moreover, Ba₃CdSi₂O₈:Eu³⁺ phosphors capture excitation energy through charge transfer transitions of Eu³⁺ ions and emit at 586 nm, 613 nm, 653 nm, and 700 nm, corresponding to the 5D₀ → 7 F₀, 5D₀ → 7 F₂, 5D₀ → 7 F₃, and 5D₀ → 7 F₄ transitions of Eu³⁺ ions, respectively. The CIE color coordinates confirm that Eu³⁺ doping shifts the color toward red, while Dy³⁺ and Ce³⁺ doping result in shifts within other parts of the chromaticity space.Öğe Highly efficient photocatalyst based on Zn2-xBaxSnO4 alloying nanoparticles with enhanced photocatalytic activity(Elsevier, 2025) Kamo, Alaa; Sönmezoğlu, Özlem Ateş; Sönmezoğlu, SavaşIn this study, an effective Zn2-xBaxSnO4 alloying nanoparticles were hydrothermally designed with a series of barium cation as alloying dopant and utilized as a photocatalyst to decompose the rhodamine B which causes harmful effects on humans such as allergic dermatitis, skin irritation, mutation, and cancer. It is noteworthy that the Zn1.988Ba0.012SnO4 alloying-based catalyst exhibited more than 99 % degradation in only 140 min in wastewater than barium-free ternary oxide. Moreover, the reaction rate of Zn1.988Ba0.012SnO4 alloying-based catalyst was enhanced to 0.032 min-1 compared with barium-free ternary oxide (0.0179 min-1). Based on scavenger trapping experiments, hydroxyl radicals are the main reactive oxygen species responsible for photocatalytic activity of Zn1.988Ba0.012SnO4 alloying-based catalyst. Besides, the photocatalytic rate was maintained 94.89 % after 5th cycle. This research not only provides a novel strategy for developing alloying-based catalysts but also unveils their potential in photoelectrochemistry and photocatalysis.Öğe Machine learning-driven analysis of activation energy for metal halide perovskites(Royal Soc Chemistry, 2025) Patel, Vimi; Sorathia, Kunjrani; Unjiya, Kushal; Patel, Raj Dashrath; Pandey, Siddhi Vinayak; Akın, SeçkinMetal halide perovskite single crystals (MHPSCs) are highly promising materials for optoelectronic applications, but their stability is hindered by ion migration, thereby impacting their performance. A key factor to understand this issue is calculating the activation energy. Electrochemical Impedance Spectroscopy (EIS) is a powerful technique for separating ionic and electronic processes, yet traditional analysis is labour-intensive, involving extensive measurements, circuit fitting, and manual data interpretation. In this study, we introduce a machine learning (ML)-driven approach to fully automate EIS analysis. EIS data, collected for MAPbI3 and MAPbBr3 across temperatures from 263 K to 343 K, enabled the creation of a large database. The developed ML model predicts EIS spectra at unknown temperatures, fits the appropriate electrical circuit, and automatically extracts passive component values to calculate the activation energy via an Arrhenius plot. This automated workflow streamlines the calculation process, offering fast and reliable activation energy predictions even when temperature data are incomplete or missing. Our approach enhances the efficiency of EIS analysis, providing valuable insights into the stability and performance of MHP SCs.Öğe Novel smart materials with high curie temperatures: Eu1.90Dy0.10Ge2O7, Eu1.90La0.10Ge2O7 and Eu1.90Ho0.10Ge2O7(Elsevier Ltd, 2025) Öztürk, Esra; Kalaycıoglu Ozpozan, Nilgün; Kalem, VolkanThe Eu1.90Dy0.10Ge2O7, Eu1.90La0.10Ge2O7 and Eu1.90Ho0.10Ge2O7 powder were obtained through a solid-state reaction method via multistep firing of stoichiometric ratios of Eu2O3, GeO2, Dy2O3, La2O3 and Ho2O3 in open atmosphere at temperatures from 800 to 1150 °C. The thermal behaviour, phase formation, SEM/EDX analysis, photoluminescence properties, Curie tempereture, dielectric and piezoelectric properties of the samples were investigated by TG/DTA, XRD, SEM, PL, TG/DTA, LCR-meter and d33-meter, respectively. The germenates having triclinic crystal system have 5D0→7F4, 5D0→7F3, 5D0→7F2, 5D0→7F1 transitions of Eu3+ ions. Also, the photoluminescent germenates show electrical properties and the piezoelectric charge constant of germenates showed Eu1.90Dy0.10Ge2O7> Eu1.90Ho0.10Ge2O7 > Eu1.90La0.10Ge2O7 trend. The Curie temperature of Eu1.90Dy0.10Ge2O7, Eu1.90La0.10Ge2O7 and Eu1.90Ho0.10Ge2O7 are 825, 844 and 838 °C, respectively. Compared to commonly used piezoelectric materials, Eu1.90Dy0.10Ge2O7, Eu1.90La0.10Ge2O7 and Eu1.90Ho0.10Ge2O7 materials with very high Curie temperatures were obtained with photoluminescent properties. © 2024 Elsevier LtdÖğe Synthesis and photoluminescent properties of Eu3+,yDy3+ doped molybdate based novel Ba0.5Ca0.5La2(MoO4)4 phosphors(Natl Inst Science Communication & Policy Research-Niscpr, 2024) Öztürk, Esra; Ebiç, MuratBa0.5Ca0.5La2-x-y(MoO4)(4):xEu(3+),yDy(3+) with doping concentrations of xEu(3+) and yDy(3+) (x =0.01, 0.03, 0.05, 0.1 and y= 0.01) phosphors were synthesized by solid state reaction method, one of the high temperature solid state methods. The reactions were carried out in an tube furnace at determined temperatures. Thermogravimetry-differential thermal analysis (TG/DTA) system was used to determine the synthesis temperature of the material and to examine its thermal behavior . The crystal structure of the material was checked with x-ray powder diffractometry (XRD), surface morphology and elemental analysis were done with scanning electron microscope (SEM). The photoluminescent properties of luminescence and excitation wavelength and luminescence duration were determined by photoluminescence spectrophotometer (PL). As a result of the analyzes made with photoluminescence spectrophotometer, three emission bands were observed at 619 nm, 652 nm and 706 nm, resulting from the characteristic D-5(0)->(7)Fj (J=2, 3 and 4) transitions of Eu-3+ ions.Öğe İnvestigation of photocatalytic and photoluminescent properties of a novel multifunctional near-uv excited nanostucture ceo2:0.1dy0.1ho(Natl Inst Science Communication-Niscair, 2024) Torun, Handan Özlü; Öztürk, Esra; Kırkgeçit, RabiaIn this study, Dy3+ doped and Ho3+ co-doped materials synthesized by the sol-gel method at different temperatures were investigated. The structural and optical properties were characterized by an x-ray powder diffract meter, thermal analysis system, scanning electron microscopy, Raman spectroscopy, FT-IR, UV-vis spectroscopy, and photoluminescence spectrophotometer. The photocatalytic performance, crucially contingent on the sintering temperature, was systematically evaluated using malachite green and methylene blue as model pollutants. Remarkably, the highest efficiency, registering an impressive 90%, was achieved for methylene blue when sintered at 1000 degrees C. For malachite green, a substantial efficiency of 62% was attained at a sintering temperature of 800 degrees C. The corresponding optical band gap, a pivotal parameter influencing photocatalytic activity, was determined to be 2.43 eV. Under the near-UV excitation at 318 nm, the CeO2:0.1Dy0.1Ho phosphor emitted photoluminescence with dominating emissions at 475 nm (blue), 559 nm (green) and 663 nm (red) corresponding to F-4(9/2)-> H-6(15/2) (blue) transition of Dy3+ ions, (F4,S2)-F-5-S-5 -> I-5(8) (green) and F-5(5)-> I-5(8) (red) transitions of Ho3+ ions, respectively.Öğe Behaviour of PLA/POSS nanocomposites: Effects of filler content, functional group and copolymer compatibilization(Sage Publications Ltd, 2021) Zeybek, Yelda Meyva; Kaynak, CevdetThe main purpose of this study was to investigate influences of three parameters on the mechanical and thermal properties of the polylactide (PLA) matrix nanocomposites filled with polyhedral oligomeric silsesquioxane (POSS) particles. For the first parameter of Filler Content, nanocomposites with 1, 3, 5, 7 wt% basic POSS structure were compared. For the second parameter of Functional Group, basic POSS structure having only nonpolar isobutyl groups were compared with three other functionalized POSS structures; i.e. aminopropylisobutyl-POSS (ap-POSS), propanediolisobutyl-POSS (pd-POSS) and octasilane-POSS (os-POSS). Finally, for the third parameter of Copolymer Compatibilization, all specimens were compared before and after their maleic anhydride (MA) grafted copolymer compatibilization. Specimens were produced with twin-screw extruder melt mixing and shaped under compression molding. Various tests and analyses indicated that the optimum filler content for the improved mechanical properties was I wt%; while the optimum structure for strength and modulus was pd-POSS structure, in terms of fracture toughness it was basic POSS structure. Additional use of MA compatibilization was especially effective for the basic POSS and os-POSS particles.Öğe Transition Metal Dichalcogenides as Effective Dopants in Nanofiber-Based Triboelectric Nanogenerators(Wiley, 2024) Karabiber, Abdulkerim; Dirik, Ömer; Okbaz, Abdulkerim; Yar, Adem; Özen, Abdurrahman; Özel, FarukTriboelectric nanogenerators (TENGs) are advanced energy harvesters that convert mechanical energy in diverse environments into electrical energy via static electrification and electrostatic induction. However, their performance needs to be improved to expand their area of use and become more practical. In this study, we introduced molybdenum disulfide (MoS2) and tungsten disulfide (WS2) as separate additives into polyacrylonitrile (PAN) to produce composite nanofibers via electrospinning, aiming to increase the electrical output of the TENGs. This method increased contact area by narrowing the nanofiber diameters, which is a key factor in enhancing the triboelectric effect. The incorporation of MoS2 or WS2, characterized by high specific surface area, interface polarization, quantum confinement effects, and strong electron acceptance and trapping capabilities, led to a significant increase in the dielectric constant and overall electrical performance of the TENGs. Experimental evaluations, connecting the TENGs to circuits with various resistive loads, determined optimal performance at a load resistance of 4.7 M Omega. In particular, the 5 wt% WS2@PAN & polyvinylbutral (PVB) and 5 wt% MoS2@PAN & PVB TENGs exhibited a remarkable peak power output of 40.5 mW, corresponding to a power density of 25.3 W/m2 and provided open circuit voltage of 1,026 V. The integration of 5 wt% MoS2 or 5 wt% WS2 led to more than a twofold increase in electrical power density compared to pristine PAN. These outcomes demonstrate the significant impact of transition metal dichalcogenides in enhancing the energy conversion efficiency of contact-separation mode TENGs, thereby contributing to the advancement of energy harvesting technology.Öğe Determining the hydrogen production potential of ConMo6Se8 chevrel phases(Iop Publishing Ltd, 2025) Gencer, Ayşenur; Surucu, Özge; Şahin, Murat; Özel, Faruk; Surucu, GökhanIn this study, the ConMo6Se8 (n = 1, 2, 3, and 4) Chevrel phases are investigated by using Density Functional Theory (DFT) to reveal their potential for photocatalytic hydrogen production. The stability conditions of these phases reveal that CoMo6Se8, Co2Mo6Se8, and Co3Mo6Se8 satisfy the thermodynamic and mechanic stability properties, while Co4Mo6Se8 does not satisfy any of these properties. Furthermore, the formation enthalpy of these phases shows that CoMo6Se8, Co2Mo6Se8, and Co3Mo6Se8 can be synthesized experimentally due to having negative formation enthalpy values. Furthermore, the thermal stabilities of the machine-learning (ML) force fields are investigated by ab-initio molecular dynamics (AIMD) calculations. The electronic properties of these phases are also investigated in detail, and it is found that Co3Mo6Se8 has a suitable band gap for photocatalytic water splitting. Concerning the investigation of the valence band and conduction band levels, it is shown that Co3Mo6Se8 has a conduction band minimum level suitable for producing hydrogen. This study is the first attempt to reveal the hydrogen production performance of the ConMo6Se8 (n = 1, 2, 3, and 4) Chevrel phases as far as the literature is concerned, paving the ground for future investigations in this field.Öğe Synthesis, characterization, and investigation of photoluminescence optima of In3+ and Gd3+ doped Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 materials(Taylor & Francis Inc, 2024) Öztürk, Esra; Özpozan, Nilgün KalaycıoğluIn this study, we investigated the photoluminescence properties and structure of the In3+ and Gd3+ doped Eu2Ru2O7-based pyrochlore materials. The samples were synthesized by solid state reaction technique, investigated structurally by X-ray powder diffraction (XRD), thermally by thermogravimetry, and differential thermal analysis, morphologically by scanning electron microscopy (SEM). The photoluminescence properties of Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 were investigated with photoluminescence spectrometer. X-ray diffraction patterns of all the samples showed that all samples had a cubic type pyrochlore crystal structure with a = b = c = 10.252 & Aring; and alpha = beta = gamma = 90 degrees. The XRD patterns demonstrate that neither the type nor the amount of doping ion alters the unit cell parameter. The SEM images of Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 reveal a regular morphology, with an average sample size ranging from 0.2 to 0.5 mu m. The elementel (EDX) analysis confirm the absence of impurity elements and showing that the theoretical and experimental element ratios are consistent with EDX analysis expectations. The pyrochlore phosphors showed broad red emission band at similar to 605 nm. This red emission can be attributed to the D-5(0)-> F-7(2) transitions of Eu3+. The phosphor co-doped with In3+ ions has a considerably longer lifetime and photoluminescence intensity than the other phosphor. Eu1.90In0.10Ru2O7 and Eu1.90Gd0.10Ru2O7 phosphors, which show transitions in the red region (at 605/606 nm,D-5(0) -> F-7(2)), are suitable for optoelectronic and white LED applications.Öğe Ternary zinc-tin-oxide nanoparticles modified by magnesium ions as a visible-light-active photocatalyst with highly strong antibacterial activity(Royal Soc Chemistry, 2024) Kamo, Alaa; Sönmezoğlu, Özlem Ateş; Sönmezoğlu, SavaşHospital-acquired infections (HAIs), especially nosocomial infections caused by antibiotic-resistant bacteria, are one of the most pressing health problems in all societies. Therefore, there is an urgent need to develop novel disinfection methods as alternatives to antibiotics to act against multidrug-resistant bacterial strains. Even though the photocatalytic disinfection phenomenon has been considered as a viable alternative compared to other proposed solutions, there is still a need to develop innovative functional materials for improving its efficacy under visible light to have a comparable impact to UV radiation. To boost the antibacterial efficacy under visible light, herein, we developed hydrothermally ternary zinc-tin-oxide (Zn2SnO4) nanoparticles modified with magnesium (Mg2+) ions at different doping ratios (0.5%, 1.0%, 1.5%, and 2.0%) as a photocatalytic disinfection agent and utilized it for the first time to kill Gram-negative (E. coli) and Gram-positive (S. aureus) pathogens that cause nosocomial infections. Moreover, we also explored how these materials interact with organic pollutants in the presence of visible light. Mg2+ cationic ions significantly enhanced the photocatalytic efficiency of ZTO nanoparticles under visible light to achieve 98% degradation of RhB dye in just 100 min, and rapidly produced numerous hydroxyl radicals as the main reactive oxygen species (ROS) responsible for the degradation, playing a key role in the nanoparticles impressive disinfection efficacy against these pathogenic bacteria. More importantly, Mg1.5@ZTO nanoparticles could effectively kill 99.76% of E. coli and 96.96% of S. aureus within only 1 h under visible light due to their smaller particle size, larger surface area, low recombination rate and greater ROS generation with oxygen vacancies. This research suggests that Mg-doped ZTO nanoparticles might be a viable and highly effective photocatalytic antibacterial agent candidate for future commercialization in healthcare and environmental applications.Öğe Beta radiation-induced thermoluminescence in pure and rare earth doped ZrO2 prepared by pechini-type sol-gel(Elsevier, 2024) Uzun, Erdem; Yıldız, Esra; Öztürk, EsraThermoluminescence properties of ZrO2, 2 , ZrO2:Gd3+, 2 :Gd 3+ , ZrO2:Gd3+-Dy3+, 2 :Gd 3+ -Dy 3+ , ZrO2:Gd3+-Yb3+, 2 :Gd 3+ -Yb 3+ , ZrO2:Gd3+-Er3+ 2 :Gd 3+ -Er 3+ and ZrO2:Gd3+-Sm3+ 2 :Gd 3+ -Sm 3+ phosphors synthesized by Pechini method were investigated. XRD measurement suggested that all the samples are monoclinic and tetragonal multiphase. Crystallite size measured using SEM is around 200 nm-250 nm. The T max -T STOP , variable dose and glow curve fitting methods were applied to the phosphors and reusability, dose responses and fading characteristics were examined. The phosphors exhibit a natural TL emission which disappeared after heat treatment. The glow curves of the pure ZrO2 2 have thirteen individual glow peaks, which include the peaks reported for the monoclinic and tetragonal phases. Although some peaks emerge at low irradiation doses, others can only be observed at high doses. Moreover, although the dopes blanched some of the peaks of pure ZrO2, 2 , they made others more intense. These peaks can be interpreted as if they emerged caused by the rare earth doping into the matrix material. On the other hand, Gd3+, 3+ , Dy3+, 3+ , Yb3+, 3+ , Er3+ 3+ and Sm3+ 3+ dopes did not alter the peak temperatures of the matrix material. As a result, the individual peak intensities are very sensitive to the dopes. Fundamental trapping parameters of the trap levels were calculated, and the results are in good agreement with the given values of activation energies in the literature. Fading experiments show the materials have both normal and abnormal fading characteristics in long and short-term storage.
