Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

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Citation - WoS: 6
Citation - Scopus: 6
Anisotropic Etching of Cvd Grown Graphene for Ammonia Sensing
(Institute of Electrical and Electronics Engineers Inc., 2022-03) Yağmurcukardeş, Nesli; Bayram, Abdullah; Aydın, Hasan; Yağmurcukardeş, Mehmet; Açıkbaş, Yaser; Peeters, François M.; Çelebi, Cem; 04.04. Department of Photonics; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
Bare chemical vapor deposition (CVD) grown graphene (GRP) was anisotropically etched with various etching parameters. The morphological and structural characterizations were carried out by optical microscopy and the vibrational properties substrates were obtained by Raman spectroscopy. The ammonia adsorption and desorption behavior of graphene-based sensors were recorded via quartz crystal microbalance (QCM) measurements at room temperature. The etched samples for ambient NH3 exhibited nearly 35% improvement and showed high resistance to humidity molecules when compared to bare graphene. Besides exhibiting promising sensitivity to NH3 molecules, the etched graphene-based sensors were less affected by humidity. The experimental results were collaborated by Density Functional Theory (DFT) calculations and it was shown that while water molecules fragmented into H and O, NH3 interacts weakly with EGPR2 sample which reveals the enhanced sensing ability of EGPR2. Apparently, it would be more suitable to use EGRP2 in sensing applications due to its sensitivity to NH3 molecules, its stability, and its resistance to H2O molecules in humid ambient.
Citation - WoS: 4
Citation - Scopus: 4
Characterization of Water Solubility and Binding of Spin Labeled Drugs in the Presence of Albumin Nanoparticles and Proteins by Electron Paramagnetic Resonance Spectroscopy
(Wiley-Blackwell, 2022-02) Sözer, Sümeyra Çiğdem; Akdoğan, Yaşar; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
Electron paramagnetic resonance (EPR) spectroscopy is an advantageous technique to monitor solubility of drugs in an aqueous solution. In the presence of a drug carrier, the bound and unbound drug fractions can be determined in the same sample simultaneously. To enhance the solubility of hydrophobic drugs, a transporter protein of bovine serum albumin (BSA) can be used directly or in the form of nanoparticle. Moreover, a cationic BSA can be used to enhance anionic drug loading. Here, drugs with different water solubility, salicylic acid (high), ibuprofen (low) and chlorambucil (none) were spin labeled and studied with EPR spectroscopy. Remarkably, it has been shown that albumin nanoparticles are much more effective than albumin proteins in dissolving hydrophobic drugs in water. Furthermore, different drug loading methods were compared, and different from other techniques drug release can be monitored directly from the NPs pellet dissolution by EPR spectroscopy.
Citation - WoS: 24
Citation - Scopus: 30
Cold Sintering as a Promising Isru Technique: a Case Study of Mars Regolith Simulant
(Elsevier, 2023-01) Karacasulu, Levent; Karl, David; Gurlo, Aleksander; Ahmetoğlu, Çekdar Vakıf; 03.09. Department of Materials Science and Engineering; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology; 03. Faculty of Engineering
Mars regolith simulant (MGS-1) was densified for the first time via a cold sintering process (CSP) as a novel in-situ resource utilization (ISRU) concept. The technique comprises the utilization of NaOH solution as a liquid media during the densification of simulant powder with <100 μm particle size. In as short as 30 min, with the increase in the NaOH concentration (from 3 M to 10 M) and processing temperature (from 150 °C to 250 °C), the relative densities of the regolith compacts and the mechanical properties were enhanced. The artifacts produced with Mars regolith simulant powder at 250 °C using 10 M NaOH solution yielded a relative density of around 88% and compressive strength reaching ∼45 MPa.
Citation - WoS: 86
Citation - Scopus: 90
Defect-Engineering Agsbte2 With High Thermoelectric Performance
(Wiley, 2023) Zhang, Yu; Li, Zhi; Singh, Saurabh; Nozariasbmarz, Amin; Li, Wenjie; Genç, Aziz; Xia, Yi; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low- and high-temperature regimes. However, there is an urgent demand for high-performance TE materials working in the mid-temperature range (400–700 K). Herein, p-type AgSbTe2 materials stabilized with S and Se co-doping are demonstrated to exhibit an outstanding maximum figure of merit (zTmax) of 2.3 at 673 K and an average figure of merit (zTave) of 1.59 over the wide temperature range of 300–673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n-type Ag2Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single-leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high-performance TE material in the mid-temperature range.
Citation - WoS: 8
Citation - Scopus: 8
Design and Fabrication of Polymer Micro/Nano Composites With Two-Level Mechanical Reinforcing Procedure
(Wiley, 2022-07) Kandemir, Ayşe Çağıl; Dönmez, Fatma; Davut, Kemal; Kaplan Can, Hatice; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Biocompatible composite production was accomplished by utilizing two-level hierarchical approach for mechanical reinforcement. A well-known commodity polymer; low-density polyethylene (LDPE), which has high-fracture toughness, yet low strength and modulus was used as the main matrix material. As the first step of hierarchy, ductile LDPE was blended with brittle polyvinylpyrrolidone (PVP), which is an eco-friendly, nontoxic and biocompatible polymer. This resulted in slight decrease of strength and drastic reduction of toughness (%70), yet modulus was increased by 78%. As the second level of hierarchy, PVP composites were introduced in LDPE. Nano-scaled Halloysite clay and micro-scaled spherical Silica particles were utilized as additives in the aforementioned PVP composites. The reason for the choice of these particles is that they are nontoxic, low-cost and in the case of Halloysite; abundant in nature. Owing to the implementation of the second level; modulus improvement was further enhanced to 150%, with additional benefits of strength increase up to 17% and less reduction in fracture toughness (minimum 51% reduction). Dynamic mechanical analysis also supported these outcomes that storage modulus of composites are higher than both LDPE and LDPE-PVP blend. The proposed biocompatible composites in the end of this study would be utilized in biomedical applications necessitating mechanical improvements.
Citation - WoS: 3
Citation - Scopus: 4
Development of Textured Lead-Free Nbt-Based Piezoelectric Materials in a Matrix, Synthesized by an Alternative Route, Via Templated Grain Growth
(Springer, 2023-02) Çoban Tetik, Hatice Şule; Suvacı, Ender; Avcı, A. Murat; Adem, Umut; Karakaya, Merve; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
In this study, (1−x)(K0.5Bi0.5TiO3-BaTiO3)−xNa0.5Bi0.5TiO3 KBT:BT = 2:1 where x = 0.8 (KBT-BT-NBT) (001) textured lead-free piezoelectric ceramics were fabricated using BT template by templated grain growth with tape casting. Unlike the commonly used matrix preparation method, which is the calcination of all raw materials in one step, the matrix phase was prepared in a different way by first preparing KBT, BT and NBT powders separately and then by calcining the mixtures of these powders, so that effect of the matrix, synthesized by this alternative route, on texture development properties was evaluated. In addition, the effect of BT template content on the grain orientation with different sintering temperature and time, structure evolution, phase stability and piezoelectric properties were investigated to assess the materials’ actuating performance. The highest Lotgering factor of 81% was achieved for the textured ceramics with 10 wt% BT templates sintered at 1150 °C for 48 h. Compared to the one-step synthesis method, similar Lotgering factor values were obtained at lower sintering temperatures in the matrix, synthesized by the alternative 2-step method. The highest piezoelectric constant, remnant polarization, strain value and depolarization temperature were also obtained from the same sample, as ~ 190 pC/N, 30 kV/cm, 25% at 50 kV/cm and ~ 165 °C, respectively. The results show that the textured, lead free K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 (KBT-BT-NBT) ceramics that are developed by using the matrix, synthesized by the alternative 2-step method, can be very promising lead-free electroceramics for high performance actuator applications.
Citation - WoS: 8
Citation - Scopus: 8
Development of Zto/Ag Transparent Electrodes for Thin Film Solar Cells
(Springer, 2022-05) Türkoğlu, Fulya; Köseoğlu, Hasan; Ekmekçioğlu, Merve; Cantaş, Ayten; Özdemir, Mehtap; Aygün, Gülnur; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
This article presents the optimization of Zinc Tin Oxide/Silver/Zinc Tin Oxide (ZTO/Ag/ZTO) multilayers to implement them in thin film solar cells as transparent electrodes. To achieve improvements on the performance of these transparent multilayers, effect of Ag and ZTO thicknesses, and position of Ag layer within the multilayer were investigated. Electrical and optical characterization of these multilayers revealed that reduced sheet resistance and improved optical transmittance can be acquired for solar cells by the optimization of thin film thicknesses and position of the Ag within the multilayer. The improvement of the electrical and optical behavior of the ZTO/Ag/ZTO structures enabled figure of merit (FoM) values up to 69.69 × 10–3 Ω−1. The performance of our multilayer electrodes was also compared with ITO and AZO electrodes. The obtained results suggest that fabricated multilayer electrodes can be a good choice for thin film solar cells.
Citation - WoS: 29
Citation - Scopus: 34
Effect of Post Fabrication Aging Treatment on the Microstructure, Crystallographic Texture and Elevated Temperature Mechanical Properties of In718 Alloy Fabricated by Selective Laser Melting
(Elsevier, 2022-08) Özer, Seren; Bilgin, Güney Mert; Davut, Kemal; Esen, Ziya; Dericioğlu, Arcan.F; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The effect of building direction and post fabrication aging treatment on the microstructure, crystallographic texture and high temperature mechanical properties of Inconel 718 (IN718) alloy fabricated by selective laser melting (SLM) method was investigated. After aging, arc-shaped structures seen in as-fabricated samples disappeared and converted into a mixture of columnar and equiaxed grains. Nano-sized γ″ and/or γ′ precipitates were formed upon aging; however, MC type carbides and Laves phase encountered in as-fabricated samples were not dissolved completely after aging. Moreover, aging did not alter the texture ((001)//building direction (BD)) of as-fabricated samples. Mechanical properties of the alloys under tension were influenced by the build direction, aging time and test temperature. As-fabricated samples produced in vertical direction exhibited higher room temperature strengths with lower ductility due to orientation of overlapped prior melt pools. Room temperature tensile test results revealed that peak aging caused a significant improvement in ultimate tensile strength (UTS), from 1066.5 MPa and 998.4 MPa to 1408.5 MPa and 1330.4 MPa whereas elongation values decreased from 27.5% and 32.2% to 19.6% and 23.7% in vertically and horizontally built samples, respectively. Peak-aged samples (aged at 700 °C for 8 h) tested at 600 °C displayed serrated regions in their stress-strain curves due to dynamic strain aging (DSA). Although strength values of the samples displayed an expected decrease by temperature, ductility of the samples reduced to minimum at temperatures around 700–800 °C, which was attributed to intermediate temperature embrittlement.
Citation - WoS: 2
The Effect of the Temperature of Heat Treatment Process and the Concentration and Duration of Acid Leaching on the Size and Crystallinity of Nano-Silica Powders Formed by the Dissociation of Natural Diatom Frustule
(American Scientific Publishers, 2022-08) Ülker, Sevkan; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The present study focused on the processing of nano-silica powders in varying sizes and crystallinities through IP: 846247.10 On: Wed, 14 Dec 2022 07:29:25 heat treatment (900-1200 degrees C), hydrofluoric acid leaching (1-7 N), and ball milling (1 h, 500 rpm) of natural Copyright American Scentfic P blishers diatom frustules. The starting natural frustules were determined to be composed of amorphous silica (88%) Delivered by Ingenta and quartz. The partially ordered crystalline low-quartz and or precursor to low-cristobalite started to form at-900 degrees C. As the heat treatment temperature increased, the crystallinity of the frustules increased from 9.3% at 25 degrees C to 46% at 1200 degrees C. Applying a ball milling reduced the mean particle sizes of the as-received and heat-treated frustules from 15.6-13.7 mu m to 7.2-6.7 mu m, respectively. Acid leaching of the as-received and heat-treated frustules resulted in a further increase in the crystallinity. Furthermore, a ball milling applied after an acid leaching was very effective in reducing the particle size of the as-received and heat-treated frustules. The mean particle size of the acid-leached frustules decreased to 774-547 nm with a crystallinity varying between 12 and 48% after ball milling. A partially dissolved amorphous phase was observed in between crystalline silica grains after acid leaching, which resulted in a rapid fracture/separation of the frustules in ball milling.
Citation - WoS: 4
Citation - Scopus: 4
Effects of Alkaline Earth Metal Additives on Methylammonium-Free Lead Halide Perovskite Thin Films and Solar Cells
(Wiley, 2022) Yüce, Hürriyet; LaFollette, Diana K.; Demir, Mustafa Muammer; Perini, Carlo A.R.; Correa-Baena, Juan-Pablo; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Organic–inorganic lead halide perovskite solar cells are regarded as one of the most promising technologies for the next generation of photovoltaics due to their high power conversion efficiency (PCE) and simple solution manufacturing. Among the different compositions, the formamidinium lead iodide (FAPbI3) photoactive phase has a bandgap of 1.4 eV, which enables the corresponding higher PCEs according to the Shockley–Queisser limit. However, the photoactive crystal phase of FAPbI3 is not stable at room temperature. The most high-performing compositions to date have reduced this problem by incorporating the methylammonium (MA) cation into the FAPbI3 composition, although MA has poor stability at high temperatures and in humid environments, which can limit the lifetime of FAxMA1−xPbI3 films. CsxFA1−xPbI3 perovskites are also explored, but despite better stability they still lag in performance. Herein, the additive engineering of MA-free organic−inorganic lead halide perovskites using divalent cations Sr2+ and Ca2+to enhance the performances of CsxFA1−xPbI3 perovskite compositions is explored. It is revealed that the addition of up to 0.5% of Sr2+ and Ca2+ leads to improvements in morphology and reduction in microstrain. The structural improvements observed correlate with improved solar cell performances at low additive concentrations.
Citation - WoS: 2
Citation - Scopus: 1
Effects of Electrospraying Parameters on Deposition of La0.3sr0.7fe0.7cr0.3o3−δ Cathode Layer on Gdc
(Wiley, 2022) Akkurt, Sedat; Sındıraç, Can; Özmen Egesoy, Tuğçe; Atıcı, Gökçe; Erişman, Elif; Erğen, Emre; Büyükaksoy, Aligül; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
High performance in intermediate temperature solid oxide fuel cells requires improvements especially in the microstructure of the cathode layer. New cobalt-free cathode materials are used because cobalt-containing cathodes have higher thermal expansion coefficients, poor long-term chemical stability, and lower mechanical stability. Recently cobalt-free cathodes have been proposed to solve these issues by using deposition methods other than electrospray deposition (ESD). In this study, ESD method is used to develop a cobalt-free cathode layer. The electrolyte layer is gadolinium-doped ceria that is deposited with La0.3Sr0.7Fe0.7 Cr0.3O3−δ (LSFCr) prepared by 2-butoxyethanol and ethylene glycol solvents as opposed to conventional solvents. Experimental ESD parameters are tested at different levels and combinations by applying statistical experimental design methods to optimize the microstructure. Coating deposited as such demonstrated higher electrochemical performance than similar electrodes fabricated by other methods.
Citation - WoS: 4
Citation - Scopus: 5
Electrospinning of Fatty Acid-Based and Metal Incorporated Polymers for the Fabrication of Eco-Friendly Fibers
(Wiley, 2022-07) Erdem, Çağlar; Isık, Tuğba; Horzum, Nesrin; Hazer, Baki; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
Accumulation of plastic wastes occupies large space in gyres of the oceans called the 7th continent. This high-level concentration of toxic plastic wastes causes harmful consequences for marine life, therefore petroleum-originated plastics must be replaced (or at least partially) with natural resources. The environmental trends in material preparation promote the utilization of greener methods and materials when the limited primary sources are considered. Starting from the fatty acid macroperoxide initiators, synthesis of bio-based polymers using less commercial chemicals and stepwise green synthesis schemes could be possible in the near future. In this research, autoxidized vegetable oil initiators (castor, limonene, and soybean oil) containing metal nanoparticles (silver, platinum, and gold) are employed for free radical polymerization of vinyl monomers. The metal loaded and vegetable oil-based polymers are processed by electrospinning and end up with the successful fabrication of continuous fibers. Ag-loaded ricinoleic acid based polymers show notable antibacterial activity against Escherichia coli. This approach offers a remarkable minimization of the initiator consumption in the synthesis of such synthetic macromolecules as well as nanoparticle containing polymer composites while still maintaining the ease of processing. Transforming the obtained graft copolymers to electrospun nanofibers facilitates the use as support materials for antibacterial surfaces.
Citation - WoS: 26
Energy Harvesting Nanogenerators: Electrospun Β-Pvdf Nanofibers Accompanying Zno Nps and Zno@ag Nps
(Elsevier, 2021-12) Zeyrek Ongun, Merve; Oğuzlar, Sibel; Kartal, Uğur; Yurddaşkal, Metin; Cihanbeğendi, Özge; Zeyrek Ongun, Merve; Oğuzlar, Sibel; Kartal, Uğur; Yurddaşkal, Metin; Cihanbeğendi, Özge; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
This paper aims to demonstrate that synthesized nano-scale zinc oxide (ZnO) and different concentrations (1, 3 and 5 wt%) of silver-doped zinc oxide (ZnO@Ag) nanoparticles (NPs), which were employed to enhance the piezoelectric content of the electrospun β-phase poly (vinylidene fluoride) PVDF nanofibers, may be an alternative for usual semiconductor dopant. The structural and morphological properties of all the synthesized materials were investigated. The impedance and the capacitance values of the manufactured nanogenerators were also investigated at room temperature. The peak-to-peak amplitude output voltage data of ZnO NPs and ZnO@Ag NPs doped PVDF-based electrospun nanomats were measured using digital oscilloscope while a finger-tapping action at a frequency of ∼1 Hz was conducted. The electrical output of 5 wt% Ag-doped ZnO-based β-PVDF nanofibers increased from 0.5 to 1.5 V compared to undoped β-PVDF samples. These findings have a wide range of auspicious applications, including energy harvesting devices, portable electronic systems, and self-powered electrical gadgets that can be worn.
Citation - WoS: 2
Citation - Scopus: 4
Enhancement of the Electrocaloric Effect in Pbzr0.7ti0.3o3 Ceramics Via La Doping: Driven by Phase Co-Existence or Defect Effects?
(Elsevier, 2022-02) Gözüaçık, Namık Kemal; Bayır, Mustafa Çağrı; Okatan, Mahmut Barış; Mısırlıoğlu, I. Burç; Alkoy, Sedat; Menşur Alkoy, Ebru; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Lattice defects and their effects have been pivotal in studies of phase transitions in a wide range of materials. Introduction of such defects into a ferroelectric material through doping of secondary elements can be tailored towards specific applications but the mechanism through which the bulk properties change is seldom scrutinized. Here we study the effect of systematic La substitution into PbZr0.7Ti0.3O3 (PZT 70/30) ceramics whereby we analyzed the temperature dependent properties and estimated the temperature changes that could be induced upon application of an external electric field, namely the electrocaloric effect (ECE). Expecting the entropic changes to be maximal under an applied field, the suitability of the La doped PZT 70/30 system for EC applications had been a motivation to undertake the current task as this composition reportedly can host a rich variety of phases depending on La content including relaxor and antiferroelectric (AFE) states. An electrocaloric (EC) temperature change of 1.15 °C in a wide range of temperatures for 8% La doping at 45 kV/cm applied field was estimated from experimental data, the possible origins of which is discussed. We were able to explain the experimental results by adopting a Landau-Ginzburg based computational approach coupled with elasticity and electrostatics whereby La sites are treated as point defects in a PZT 70/30 lattice. The gradual slanting of the hystereses and reduction of the transition temperature in the samples with increasing La content is claimed to be a direct consequence of the electrical fields due to formation of dipolar defect complexes as backed by our simulations. The ECE is discussed in the light of the simulations and recent results for AFE ceramics.
Citation - WoS: 2
Citation - Scopus: 5
Experimental Modeling of Antimony Sulfides-Rich Geothermal Deposits and Their Solubility in the Presence of Polymeric Antiscalants
(Elsevier, 2022-05) Karaburun, Emre; Sözen, Yiğit; Çiftçi, Celal; Şahin, Hasan; Baba, Alper; Akbey, Ümit; Yeşilnacar, Mehmet İrfan; Erdim, Eray; Regenspurg, Simona; Demir, Mustafa Muammer; 01. Izmir Institute of Technology; 04.04. Department of Photonics; 03.03. Department of Civil Engineering; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science
Antimony (Sb)-rich geothermal deposits have been observed in many geothermal power plants worldwide. They occur as red-colored, sulfidic precipitates disturbing energy-harvesting by clogging the geothermal installations. In order to prevent the formation of this scale, information on its physicochemical features is needed. For this purpose, Sb-rich sulfide-based deposits were synthesized at controlled conditions in a pressurized glass reactor at geothermal conditions (135 °C and 3.5 bar). Various polymeric antiscalants with different functional groups, such as acrylic acid, sulphonic acid, and phosphonic acid groups were tested for their effect on Sb sulfide solubility. An additional computational study was performed to determine the binding energy of Sb and S atoms to these groups. The results suggest that sulfonic acid groups are the most affective. Therefore, it was concluded that these macromolecule containing sulfonic acid groups and poly (vinyl sulfonic acid) derivatives could potentially act as antiscalants for the formation of antimony sulfide.
Citation - WoS: 46
Citation - Scopus: 50
Highly Porous Poly(o-Phenylenediamine) Loaded Magnetic Carboxymethyl Cellulose Hybrid Beads for Removal of Two Model Textile Dyes
(Springer, 2022-10) Arıca, Tuğçe Aybüke; Balcı, Fadime Mert; Balcı, Sinan; Arıca, Mehmet Yakup; 04.04. Department of Photonics; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Ensuring the removal of complex dyes from wastewater is a topic of great interest as it is vital for the environment. The present study reports a facile preparation method for poly(o-phenylenediamine) [p(o-PDA)] micro-particles loaded to magnetic carboxymethyl cellulose (CMC) hydrogel beads as adsorbents. The prepared products were characterized by FTIR, TGA, VSM, SEM, BET, and zeta sizer. The Fe3O4@p(o-PDA)@CMC beads were used for the removal of Reactive Blue 4 (RB-4) and Congo Red (CR) textile dyes from an aqueous medium. Different factors, such as adsorbent dose, initial pH, ionic strength, contact time, temperatures, and initial RB-4 and CR concentrations were examined. The maximum adsorption capacities of the RB-4 dye and CR at optimum pH 5 reached 398.7 and 524.6 mg/g in 120 min, respectively. The adsorption of RB-4 and CR on the hybrid magnetic beads can be due to the electrostatic, hydrogen bonding, and π-π interactions. Moreover, the magnetic hybrid beads showed easy regeneration ability and good reusability. The adsorbent can be a very good candidate for the efficient removal of micro-pollutant from wastewater.
Citation - WoS: 3
Citation - Scopus: 5
Hybrid Photonic-Plasmonic Mode-Coupling Induced Enhancement of the Spontaneous Emission Rate of Cds/Cdse Quantum Emitters
(Elsevier, 2022-02) Gökbulut, Belkıs; İnanç, Arda; Topçu, Gökhan; Özçelik, Serdar; Demir, Mustafa Muammer; 04.01. Department of Chemistry; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
n this paper, a hybrid photonic-plasmonic resonator, which comprises an electrospun polymer fiber with a micrometer diameter and a core/shell nanostructure with a gold nanoparticle core, is constructed to investigate the dynamics of the coupled spontaneous emission of CdS/CdSe quantum dots (QDs). The gold nanoparticle core; covered with a silica shell, anchored with individual CdS/CdSe QDs, is placed inside a hollow cylindrical nanocavity formed on the surface of the microfiber to enable integration of the optical mode with the plasmonic effect, which is induced by the localized surface plasmons of the metal nanoparticle being present in the vicinity of the dipoles. The spontaneous emission rate of the QDs, coupled into the hybrid photonic-plasmonic mode, is measured to enhance by a factor of 23 via a time-resolved experimental technique. This result suggests that the regeneration of the optical mode-field inside the photonic-plasmonic resonator through the interaction of the dipoles with the localized surface plasmons of a metal nanoparticle strongly enhances the density of the electromagnetic states of the quantum emitters to facilitate an enhanced spontaneous emission within the host medium of the proposed polymer based-photonic structure.
Citation - WoS: 7
Citation - Scopus: 7
Hydrothermal Synthesis of Potassium–sodium Niobate Powders
(Wiley, 2022-06) Pişkin, Cerem; Karacasulu, Levent; Ischia, Gloria; Bortolotti, Mauro; Ahmetoğlu, Çekdar Vakıf; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 01.01. Units Affiliated to the Rectorate; 03. Faculty of Engineering
Potassium–sodium niobates (KxNa1−xNbO3, 0 < x < 1, KNN) were hydrothermally synthesized under varying alkaline ratios (K+/Na+), total hydroxide concentration, reaction temperature, and time. Compositional surveys were developed by using Rietveld analyses derived quantitative volume fractions. The data demonstrated that phase pure KNN synthesis can be achieved by reacting the niobium source with the hydroxide solution having 6 M total hydroxide concentration, cation ratio (K+/Na+) of above 6 at temperatures ≥200°C for 24 h. Dissolution–precipitation events through intermediate products including hexaniobates were postulated as a plausible formation mechanism. It was shown also that the single-phase KNN approaching the morphotropic phase boundary (MPB) could be obtained by further incorporation of sodium ions into the crystal via post-annealing at 800°C/2 h, following the hydrothermal synthesis.
Citation - WoS: 6
Citation - Scopus: 15
Improvement of Photophysical Properties of Cspbbr3 and Mn2+:cspb(br,cl)(3) Perovskite Nanocrystals by Sr2+ Doping for White Light-Emitting Diodes
(American Chemical Society, 2022-06) Yüce, Hürriyet; Mandal, Mukunda; Yalçınkaya, Yenal; Andrienko, Denis; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
All-inorganic metal halide perovskite nanocrystals (NCs) having the general formula ABX(3), where A is a monovalent cation, for example, Cs+, B is a divalent cation, typically Pb2+, and X is Cl-, Br-, I-, or their binary mixture, show potential in optoelectronic devices. In this work, we explore the effect of B-site doping on the optoelectronic properties of CsPbX3 NCs (X = Br, Cl). First, the Pb2+ ions in the pristine CsPbBr3 NC are partially substituted by Mn2+ ions. The alkaline earth metal strontium is then doped on both pristine and the Mn2+-substituted NCs. We found that a small percentage of Sr2+ doping remarkably improves the photoluminescence quantum yield of CsPbBr3 and Mn2+-state emission in Mn2+:CsPb(Br,Cl)(3) NCs. Perovskite NC film/ poly(methyl methacrylate) composites with all four NC variants were used in a white light-emitting diode (WLED), where Sr2+ doping increased the luminous efficiency of the WLED by similar to 4.7%. We attribute this performance enhancement to a reduced defect density and an attenuated microstrain in the local NC structure.
Citation - WoS: 5
Citation - Scopus: 7
An in Vivo Zebrafish Model Reveals Circulating Tumor Cell Targeting Capacity of Serum Albumin Nanoparticles
(Elsevier, 2022-09) Çakan Akdoğan, Gülçin; Ersöz, Esra; Sözer, Sümeyra Çiğdem; Gelinci, Emine; 01. Izmir Institute of Technology
Nanoparticles are promising tools of drug delivery in modern medicine. There is a need for fast and reliable models for in vivo validation of newly developed nanocarriers. Here, we report a fast and easy zebrafish larval model to study the biodistribution and cancer cell targeting capacity of serum albumin nanoparticles in vivo. Fluorescently tagged Bovine Serum Albumin Nanoparticles (BSA-NPs) delivered intravenously to the zebrafish larvae, can be used to study the biodistribution via live imaging. We showed that the BSA-NPs were instantly distributed to the larval vasculature including the brain, without causing any toxicity. The clearance of nanoparticles from the body occurred within few days, which gives sufficient time to study anti-cancer efficiency of the BSA-NPs. Next, we asked whether the BSA-NPs can target the cancer cells in circulation. We established a circulating tumor cell (CTC) xenograft model and described a quantitative method for colocalization and cancer cell death analysis in the intact live organism. We showed that BSA-NPs effectively found and localized to MCF7 cells in vasculature which were killed upon doxorubicin delivery. Interestingly, folic acid coating of BSA-NPs caused faster colocalization but did not increase the overall cell death. This is the first report of the biodistribution, toxicity and anti-cancer effectiveness of serum albumin-based nanoparticles in the zebrafish model. Moreover, here we report for the first time that BSA-NPs are able to target the CTCs in an in vivo model. The zebrafish CTC model and the analysis protocol reported here can be used to assess CTC targeting capacity of nanoparticles and devise patient specific CTC targeting tests.

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