Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Makale Koleksiyonu
Bu koleksiyon için kalıcı URI
Güncel Gönderiler
Öğe The performance of Ag2S/X (X: Co and Ni) nanocrystals as counter electrodes in dye-sensitized solar cells(Elsevier Ltd, 1 September 2025) Özel, Sultan Süleyman; Bulucu, Esen Dağasan; Sarılmaz, Adem; Özel, FarukIn the present study, Silver sulfide (Ag2S)-based nanocrystals (NCs) were synthesized by employing a facile hot injection method. These NCs are utilized as counter electrodes on dye-sensitized solar cells (DSSCs), representing a smart approach that utilizes these NCs as catalysts instead of platinum (Pt) for the first time. The study provides a comparative analysis of the performance of Ag2S-based counter electrodes (CEs) in DSSCs technologies the traditionally compared Pt-based electrodes under identical conditions. The findings showed that the Ag2S-based DSSCs exhibited a power conversion efficiency (ƞ) that was approximately 5.2 % higher than that of the platinum-based DSSCs. Consequently, the results of this study demonstrate that Ag2S-based NCs possess the potential to function as novel counter electrode materials for low-cost, Pt-free solar cells. Moreover, the results of this study bear considerable implications for the development of cost-effective and sustainable solar energy solutions. The advent of Ag2S-based NCs signifies a significant milestone in the quest for sustainable and efficient energy solutions. This study also invites further exploration into other potential material combinations and synthesis methods that could enhance the properties and performance of DSSCs.Öğe Investigation of the Ku band electromagnetic properties of red mud sintered by different methods(Springer, June 2025) Kuru, Mikail; Rüşen, Aydın; Duysak, Hüseyin; Yiğit, EnesThe main objective of this study is to reveal the potential of using red mud, a significant metallurgical waste, as an electromagnetic wave absorber material. In this study, initially, red mud obtained from the aluminium sector was analysed physically, chemically, mineralogically, and thermally. Subsequently, samples produced using three different methods (dry-sintered, slip casting-sintered, and mechanically pressed-sintered) were characterized in the Ku band range using a Vector Network Analyzer (VNA) and waveguide measurement kit (WR62) and the EM properties including permittivity and permeability were compared. Permittivity, permeability and loss tangents of the materials corresponding to the Ku band of materials were given. The analysis revealed that the main parameters affecting EM properties are particle size and porosity ratio. In this context, the slip casting-sintered red mud sample showed higher tanδε and tanδμ values compared to the other two production methods. In addition, reflection loss (RL) values of materials were obtained and compared. The study concluded that the shaping method affects the EM properties and holds promise for the use of red mud as an electromagnetic wave absorber material.Öğe Biopolymer supported silicon carbide for enhanced photocatalytic hydrogen evolution reaction(Elsevier Ltd, 1 October 2025) Genç, Münevver Tuna; Sarılmaz, Adem; Aslan, Emre; Özel, Faruk; Potrich, Cristina; Ersoz, MustafaIn photocatalytic hydrogen evolution reactions, SiC catalyst was templated with biopolymers (cellulose, chitin, chitosan, sodium alginate) in a reaction medium containing eosin Y dye and triethanolamine. Biopolymers act as biotemplate and mediator, provide easy dispersion, hydrophilicity, morphological transformation and adhesion to semiconductor with the help of functional groups. The photo-deposition of MoSx and Pt in aqueous solution is performed on biopolymer-SiC nanocomposite to obtain biopolymer-SiC/MoSx and biopolymer-SiC/Pt by reducing (NH4)2MoS4 and H2PtCl6·6H2O, respectively. Sodium alginate-SiC/MoSx showed highest photocatalytic activity which is approximately 158-, 34- and 13 times higher than bare SiC, bare sodium alginate and sodium alginate-SiC catalyst, respectively. Moreover, the solar-to-hydrogen efficiencies are achieved about 19.83% under solar light irradiation for the sodium alginate-SiC/MoSx catalyst. In addition, photo-deposited MoSx and Pt on biopolymer-SiC nanocomposite resulted in enhanced photocatalytic activity and stability because of increased active sites and enhanced electron transfer ability due to the co-catalyst effect.Öğe Trait anxiety, dispositional hope and mental well-being: examining longitudinal mediation(BioMed Central Ltd, 2025) Akat, Muhammedhe associations among trait anxiety, dispositional hope, and mental well-being have been examined in cross-sectional studies. However, no longitudinal research has examined the relationships between these variables, creating a significant gap in the literature. This study collected data at two-time points (T1–T2) at six-month intervals. The study’s participants were 297 adolescents. This study employed a longitudinal design to investigate whether trait anxiety (T2) and dispositional hope (T2) mediate the association between trait anxiety (T1) and mental well-being (T2) in a sample of Turkish adolescents. A cross-lagged panel model was used in this study for a half-longitudinal design to test mediation. The results showed that dispositional hope (T2) had a longitudinal mediating role in the relationship between trait anxiety (T1) and mental well-being (T2). Additionally, it was found that trait anxiety (T2) had a longitudinal mediating role in the relationship between trait anxiety (T1) and mental well-being (T2). Based on the findings of this study, mental health professionals may utilize hope-oriented interventions in the prevention of trait anxiety among adolescents.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 Assessing the impacts of titanium dioxide nanoparticles on seed germination and seedling growth in wheat(Konya Teknik Univ, 2024) Ateş Sönmezoğlu, Özlem; Kamo, Alaa; Bozkaya, Büşra; Sönmezoğlu, SavaşWheat is the main food source for key nutrients in humans, hence any new research into boosting wheat quality and yield is vital. Recent advances in nanotechnology have made nanoparticles appropriate for use in agriculture. Titanium dioxide (TiO2) nanoparticles have a considerable impact on plants, but further research is required to make them commercially feasible. Herein, we evaluate the impact of TiO2 nanoparticles not only on the germination of seeds but also on the growth of wheat (Triticum aestivum L.) through soil application. The experimental findings reveal that TiO2 treatment at concentrations up to 2000 mg/L in seeds planted in Petri dishes has a favorable effect on wheat root and shoot length, whereas it has a suppressive effect at higher concentrations. As expected, a similar trend is observed for plant shoot length in the soil treatment with beneficial effects recorded up to a dosage of 60 mg/kg. In conclusion, the beneficial effects of TiO2 nanoparticles on seed germination and plant growth may have a big financial impact on horticulture, agriculture, and the energy industry-particularly on the manufacturing of biofuels.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.
