Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4719

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Citation - Scopus: 19
Advanced Sensor and Detection Materials
(John Wiley and Sons Inc., 2014) Tiwari, Ashutosh; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Presents a comprehensive and interdisciplinary review of the major cutting-edge technology research areas-especially those on new materials and methods as well as advanced structures and properties-for various sensor and detection devices. The development of sensors and detectors at macroscopic or nanometric scale is the driving force stimulating research in sensing materials and technology for accurate detection in solid, liquid, or gas phases; contact or non-contact configurations; or multiple sensing. The emphasis on reduced-scale detection techniques requires the use of new materials and methods. These techniques offer appealing perspectives given by spin crossover organic, inorganic, and composite materials that could be unique for sensor fabrication. The influence of the length, composition, and conformation structure of materials on their properties, and the possibility of adjusting sensing properties by doping or adding the side-groups, are indicative of the starting point of multifarious sensing. The role of intermolecular interactions, polymer and ordered phase formation, as well as behavior under pressure and magnetic and electric fields are also important facts for processing ultra-sensing materials. The 15 chapters written by senior researchers in Advanced Sensor and Detection Materials cover all these subjects and key features under three foci: 1) principals and perspectives, 2) new materials and methods, and 3) advanced structures and properties for various sensor devices. © 2014 Scrivener Publishing LLC. All rights reserved.
Amwc 2013: Advanced Materials World Congress (izmir, Turkey, September 16–19, 2013)
(Walter de Gruyter GmbH, 2013-03) Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Recent decades witnessed an explosion of new materials and new ways to fabricate and use naturally occurring and engineered materials. Scientists and engineers from various fields refer to this development to understand materials structure fundamentally and accordingly material properties and function. Currently, it is crucial to provide a global platform for researchers and engineers from both academia and industry to present their research results and activities with a special attention from an interdisciplinary aspect of advanced materials.
Citation - Scopus: 1
Assessment of Separation and Agglomerationt Tendency of Non-Metallic Inclusions in an Electromagnetically Stirred Aluminum Melt
(Springer, 2023) Li, Cong; Dang, Thien; Gökelma, Mertol; Zimmermann, Sebastian; Mitterecker, Jonas; Friedrich, Bernd; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Presence of non-metallic inclusions (NMIs) reduces surface quality and mechanical properties of aluminum products. The development of good NMIs removal practices relies on the understanding of inclusion behaviors with respect to separation and agglomeration particularly in the turbulent flow. In the scenario of electromagnetically induced recirculated turbulent flow, the concerned behaviors of inclusions with different sizes have rarely been investigated experimentally. In the presented study funded by AMAP Open Innovation Research Cluster, reference materials were prepared with uniformly distributed NMIs (SiC and MgAl2O4) via an ultrasound-involved casting route. Reference materials were charged into an aluminum melt where turbulent flow was promoted via electromagnetic force. Microscopical analysis shows non-significant agglomeration tendency of SiC, MgAl2O4, and TiB2 inclusion. Time-weight filtration curve, PoDFA, and Spark Spectrometer results suggest a strong dependence of separation rate on particle size. Analytical models were established to estimate the collision rate of particles and to evaluate separation probability of different sized particles. © 2023, The Minerals, Metals & Materials Society.
Bir fosfor dönüşümlü beyaz led paketi
(Türk Patent ve Marka Kurumu, 2020)
Bu buluş bir fosfor dönüşümlü beyaz LED paketi ile, özellikle fosfor kullanım miktarını azaltmayı ve ışık rengi sıcaklığının ayarlanmasını sağlayan cam küre formunda optik elemanlar içeren bir fosfor dönüşümlü beyaz LED paketi ile ilgilidir.
Darbe altında ışıma yapan polimerik filmler ve lif demetlerinin üretilmesi ve uygulamaları
(2016) Demir, Mustafa M.; İncel, Anıl; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Tribolüminesans (TL) malzemeler darbe altında ışıma özelliğine sahip kristal yapılardır. Bu projede, organik ve metal yapıları bir arada bulunduran iki TL kristal (EuD4TEA ve Cu(NCS)(py)2(PPh3)) elde edilmiş ve mikrometre büyüklüğündeki tanecikler PMMA (poli metil metakrilat), PS (polistiren), PU (poliüretan) ve PVDF (polivinilflorür) saydam özellikteki polimerler kullanılarak ince-katmanlı film, elektrospun lif demetleri ve nano boyutundaki tanecikler elde edilen matrisler ile entegre edilmiştir. Kompozit malzemelerin elde edilmesi için iki farklı deneysel metod geliştirilmiştir: i) yükleme işlemi ve ii) yüzeye depolama işlemi. Kompozit malzemelerin TL performansları bu tez için özel tasarlanan atış kule sistemi ile ölçülmüştür. Bunun yanı sıra, atomik kuvvet mikroskobu (AFM), taramalı elektron mikroskobu (SEM) polimerlerin ve kompozit malzemelerin topografik ve morfolojik özellklerini değerlendirmek için kullanılmıştır. Ayrıca, flüoresans mikroskobu kullanılarak kompozit malzemelerin emisyon sırasındaki renk sinyalleri belirlenmiştir. Son olarak piezoelektrik özellikleri osiloskop kullanılarak belirlenmiştir. Tüm bu cihazlardan elde edilen sonuçlar değerlendirildiğinde, deneysel prosedür, kristal taneciklerin boyutları, polimer malzemenin formu ve yüzey özelliği, kullanılan kristallerin kompozit içindeki miktarı bu çalışmada temel parametreler olarak belirlenmiştir. PU esaslı elde edilen film ve lif demeti kompozitler PMMA, PS, ve PVDF esaslı kompozitlerden daha iyi sonuç göstermiştir. Bunun nedeni olarak, film esaslı kompozitler için ince katmanlı PU filmin daha engebeli ve saydam bir yüzey olması; lif esaslı kompozitler için elektrospun PU liflerin daha küçük yapılardan oluşması, tüm bunlara ek olarak PU’nın kimyasal olarak TL özellikteki iki kristalle kimyasal etkileşim oluşturulması gösterilebilir.
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.
Development of Graphene Nanoplatelets Reinforced Aluminium Matrix Nanocomposites by a Combination of Semi-Solid Stirring and Ultrasonic Treatment
(European Conference on Composite Materials, 2016) Kandemir, Sinan; Aydoğan, Yücel; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Graphene Nanoplatelets (GNPs) consisting of graphene layers with a thickness less than 100 nm have recently emerged as a promising reinforcement type owing to their excellent physical and mechanical properties to improve mechanical properties of alloys beyond ceramic nanoparticles. Although there are numerous studies on GNPs reinforced polymer matrix composites in the literature, the number of studies related to the incorporation of GNPs in metal matrices is limited. It is a challenging task to incorporate and uniformly distribute GNPs into liquid metals due to their poor wettability and large surface-to-volume ratio. The purpose of this study is to effectively disperse GNPs into liquid aluminium. 0.5 wt.% GNPs with an average thickness of 50-100 nm and size of 5 ?m were first incorporated into A360 aluminium alloy under semi-solid stirring, and then the composite was ultrasonically treated in fully liquid state. The microstructural investigation of the nanocomposites by optical and scanning electron microscopy may suggest that relatively uniform distribution and effective deagglomeration of GNPs in the matrix were achieved. The hardness of the GNPs reinforced nanocomposites increased in comparison with that of semi-solid stirred and ultrasonically processed A360 alloy without reinforcement, indicating the potential of GNPs for strengthening metals. © 2016, European Conference on Composite Materials, ECCM. All rights reserved.
Citation - Scopus: 8
Development of Lightweight Geopolymer Composites Containing Perlite and Vermiculite
(International OCSCO World Press, 2023) Korniejenko, Kinga; Pławecka, Kinga; Bulut, Alperen; Şahin, Baran; Azizağaoğlu, Göksu; Figiela, Beata; 01. Izmir Institute of Technology
Purpose: The aim of this work was to prepare and characterise geopolymer composites containing lightweight aggregates-perlite and vermiculite. Design/methodology/approach: The geopolymer matrix was prepared on the basis of fly ash, sand and a 6M sodium hydroxide solution with sodium silicate. The properties of the materials were tested 28 days after the preparation of the samples. The following research methods were used to characterise the composites: compressive and flexural strength tests, microstructural tests using a scanning electron microscope, and thermal conductivity were measured. Findings: The results obtained showed a slight effect of the additives on the strength properties. Lightweight aggregates are characterised by good coherence with the matrix material. Their addition allowed to reduce the density and lowered the thermal conductivity of the materials. The results obtained indicate that the proposed additives can improve the properties of the geopolymer composite for use in the construction industry. Research limitations/implications: Further research should focus on geopolymer composites with perlite and involve fire-resistant and water-absorption tests. Practical implications: The production of lightweight building materials brings a number of benefits, such as reducing the density of building elements and, at the same time, the entire structure, which results in a reduction in their weight, as well as lower transport costs. Such elements have better thermal and acoustic insulation, reflected in the parameters of buildings. An additional advantage is the reduced environmental impact through better insulation properties, lower fuel consumption during transport, etc. Originality/value: The density of the material can be reduced by using lightweight aggregates or obtaining porous material in the foamed process. In the case of geopolymer composites, a number of studies related to foamed materials have been provided, but there is only a few previous research connected with lightweight aggregates such as perlite and vermiculite. © by International OCSCO World Press. All rights reserved. 2023.
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: 36
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.
Fabrication of Bi2212 Single Crystal Bolometer for Detection of Terahertz Waves
(Springer Verlag, 2017) Semerci, Tuğçe; Demirhan, Yasemin; Miyakawa, Nobuaki; Wang, Huabing; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
Terahertz (THz) radiation is in powerful region of electromagnetic spectrum because of prosperous application areas yet deficiency still exists about sources and detectors in despite of improvements of the research field in this range. This gap can be filled by focusing on development of THz detectors. Therefore, bolometers were preferred through many detectors due to detection sensitivity above 1 THz. In this study, Bi2Sr2CaCu2O8+δ (Bi2212) single crystals were used to fabricate THz bolometric detector. Bi2212 single crystals were transferred on sapphire substrate by cleavage process and e-beam lithography and ion beam etching were used to fabricate the microchip clean room facilities. Customdesigned cryogenic cryostat was used for a-b axis electrical and THz response measurements with liquid nitrogen cooled system. After electrical measurements, Bi2212 microchips detected the signals using Stefan-Boltzmann Lamp and response time were calculated. This study have shown with our experimental results that Bi2212 single crystals are potential candidates for THz bolometric detectors.
Citation - Scopus: 2
Fabrication of Polymer Nanofiber-Conducting Polymer Fabric and Noncontact Motion Sensing Platform
(Trans Tech Publications, 2018) Mutlu, Mustafa Umut; Akın, Osman; Demir, Mustafa Muammer; Yıldız, Ümit Hakan; 03.09. Department of Materials Science and Engineering; 04.01. Department of Chemistry; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
Conductive polymer-electrospun polymer nanofiber network was combined to host iron oxide nanoparticles providing micrometer thick sensing interface. The sensor has fabricated as freestanding fabric exhibiting 10 to 100 KOhm base resistivity upon bias applied. The moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology.
Ferroelectricity of Ca9fe(po4)7 and Ca9mn(po4)7 Ceramics With Polar Whitlockite-Type Crystal Structure
(Sivas Cumhuriyet Üniversitesi, 2020) Adem, Umut; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Ca9Fe(PO4)7 is a member of the double phosphate family having polar whitlockite-type crystal structure. The phase transition from the room temperature polar R3c to the high temperature non-polar R c phase has been called a ferroelectric phase transition using complementary experiments such as temperature dependent second harmonic generation and dielectric constant measurements however no ferroelectric hysteresis measurement has been reported. In order to be able to call these polar materials ferroelectric, measurement of a saturated ferroelectric hysteresis loop is necessary to demonstrate that the electrical polarization of these materials is switchable. In order to realize this goal, we have synthesized Ca9Fe(PO4)7 as well as structurally identical Ca9Mn(PO4)7 using solid state synthesis. Crystal structure of the ceramics were confirmed using Rietveld refinement of the x-ray diffraction (XRD) patterns. Differential scanning calorimetry (DSC) measurements revealed phase transition temperatures of 848 and 860 K for Ca9Fe(PO4)7 and Ca9Mn(PO4)7, respectively. Our ferroelectric hysteresis measurements and current electric field loops (I-E) derived from the hysteresis loops showed that the loops cannot be saturated and the direction of the electrical polarization of both materials cannot be switched up to the largest applied electric field of 100 kV/cm. Possible origins of this behaviour are discussed.
Ferroelektrik (1-x)BaTiO3-xBi(Li1/3Ti2/3)O3(0≤x≤0.2) sisteminin elektrokalorik özelliklerinin belirlenmesi
(2018) Adem, Umut; Çağın, Tahir; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Bu projede BaTiO3 bazlı iki farklı malzeme sisteminin sentezi, yapısal, dielektrik, ferroelektrik, elektrokalorik karakterizasyonları yapılarak, farklı mekanizmaların elektrokalorik etkiye etkisi ayrıntılı biçimde incelenmiştir. İlk olarak (1-x)BaTiO3-xBi(Li1/3Ti2/3O3) (0.02?x?0.08) sistemi çalışılmıştır. Bu sistemde literatürde gözlenen kabuk-çekirdek yapısının elektrokalorik etkinin mekanizmalarının anlaşılmasını engelleyeceği fikrinden hareketle, sinterleme öncesi parçacık boyutu yüksek enerjili bilyalı öğütücü yardımıyla düşürülerek difüzyonun daha hızlı gerçekleşmesi sağlanmış ve kabuk-çekirdek yapısı gözlenmemiştir. Sıcaklığa bağlı dielektrik ve ferroelektrik polarizasyon ölçümleri, bu sistemde kompozisyona göre değişen sıcaklıklarda ferroelektrik-antiferroelektrik ve antiferroelektrik-paraelektrik olmak üzere iki farklı faz geçişi olduğuna işaret etmektedir. Bu ilginç ve değişik faz geçişlerini doğrulamak için akım yoğunluğu-elektrik alan grafikleri çizdirilmiş ve gerinme elektrik alan ölçümleri yapılmıştır. Ferroelektrik antiferroelektrik faz geçiş sıcaklıklarında göreceli olarak yüksek elektrokalorik sıcaklık değişimleri gözlenmiştir (22 kV/cm elektrik alan altında yaklaşık 0.66 Kelvin). İkinci olarak ise faz diyagramı literatürdeki bir çalışmadan alınan Ba0.80Sr0.20Ti1-xZrxO3 (0?x?0.10) sistemi çalışılmıştır. Bu sistemde de faz diyagramındaki farklı bölgelerde çalışan farklı mekanizmaların elektrokalorik etkiyi nasıl etkilediği ortaya çıkarılmıştır. Elektrokalorik etki, faz geçişinin keskinliği (1. dereceden faz geçişi olup olmadığı), farklı ferroelektrik fazların bir arada olduğu noktalara yakınlık ve tane boyutu ile kontrol edilebilir. Bu projede en yüksek elektrokalorik etki perovskit yapının B pozisyonunda Zr içermeyen Ba0.80Sr0.20TiO3 örneğinde görülmüştür. Bunun nedeni bu kompozisyonunda faz geçişinin keskinliğidir. Zr katkısıyla faz geçişi yayvanlaşmış, fakat aynı zamanda farklı ferroelektrik fazların bir arada ya da yakın olduğu kompozisyonlar için elektrokalorik etki göreceli olarak yüksek çıkmıştır.
Frit fırını refrakterlerinin izotermal korozyon testi
(2007) Akkurt, Sedat; Balıkoğlu, Fatih; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Proje kapsamında değişik sanayi kuruluşlarından refrakter numuneleri temin edilmiş ve bu numuneler SEM, EDX, XRD, Optik mikroskop ve mekanik test cihazı ile karakterize edilmişlerdir. Korozyon testlerinde kullanmak amacıyla alümina ve zirkonya krozeler imal edilmiştir. 15x15x115mm ebatlarında kesilen refrakter numuneler 1750o C kapasiteli dikey boru fırının sıcak bölgesinde bulunan ve içinde erimiş frit bulunan kroze üzerine sarkıtılmıştır. Frit eriyiği içinde önceden belirlenen sürelerde yarı daldırılmış durumda bekletilen numuneler fırının soğumasını takiben dikine dilimlenerek oransal alan kayıpları ölçülmüş ve korozyon miktarı belirlenmiştir. Testler hem opak ve hemde transparan frit ile yapılmıştır. Test düzeneği ayrıca refrakter numunelerin frit eriyiği içinde kısmen daldırılarak ve döndürülecek şekilde tasarlanmıştır. Refrakterlerin korozyon direnç ölçümleri öncelikle statik deneyler yapılarak incelenmiştir. Refrakter numunelere ilk olarak ön testler yapılarak sıcaklık, zaman parametreleri için çalışma aralığı öngörülmüştür. Refrakterlerin korozyon sonrası mikroyapıları postmortem incelemeleri için optik mikroskop, SEM ve XRD ile incelenmiştir. Sayısal korozyon verileri full faktöriyel dizayn kullanılarak planlanıp istatistiksel analize tabi tutularak ANOVA tablosu hazırlanmıştır. Dinamik testler ile frit fırınlarında eriyik akışına maruz kalan refrakterlerin korozyon davranışları gözlenmiştir. Mulitik tuğlaların andaluzit esaslı tuğlalara göre daha iyi performans gösterdikleri. Her iki alüminosilikat tuğlada da ZnO.Al2O3 fazının frit-tuğla arayüzeyinde çökeldiği gözlenmiştir.
Future Applications of Artificially-Synthesized Organic Molecules Containing Transition-Metal Atoms
(Elsevier, 2018) Mayda, Selma; Kandemir, Zafer; Bulut, Nejat; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of Science
Artificially-synthesized organic molecules which contain transition-metal atoms offer new possibilities for applications in the electronics, pharmaceutical, and chemical industries. Hence, developing an understanding of the electronic properties of this kind of organic molecules is important. With this purpose, here we study the electronic properties of metalloproteins, metalloenzymes, and Ru-based dye molecules as examples for this kind of organic molecules. In particular, we perform combined Hartree-Fock (HF) and quantum Monte Carlo (HF+QMC) calculations, as well as combined density functional theory (DFT) and QMC (DFT+QMC) calculations to study the electronic properties of these molecules. Our results show that new electronic states named as impurity bound states (IBS) form in metalloproteins, metalloenzymes, and Ru-based dye molecules. We show that the electron occupancy of IBS is critically important in determining the low-energy electronic properties of these molecules. In this respect, the IBS may play a central role in developing new applications based on artificially-synthesized organic molecules containing transition-metal atoms. © 2018 Elsevier Inc. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 3
Growth and Characterization of Cdte Absorbers on Gaas by Mbe for High Concentration Pv Solar Cells
(John Wiley and Sons Inc., 2015-11) Arı, Ozan; Polat, Mustafa; Karakaya, Merve; Selamet, Yusuf; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of Science
CdTe based II-VI absorbers are promising candidates for high concentration PV solar cells with an ideal band gap for AM1.5 solar radiation. In this study, we propose single crystal CdTe absorbers grown on GaAs substrates with a molecular beam epitaxy (MBE) which is a clean deposition technology. We show that high quality CdTe absorber layers can be grown with full width half maximum of X-ray diffraction rocking curves (XRD RC) as low as 227 arc-seconds with 0.5% thickness uniformity that a 2 μm layer is capable of absorbing 99% of AM1.5 solar radiation. Bandgap of the CdTe absorber is found as 1.483 eV from spetroscopic ellipsometry (SE) measurements. Also, high absorption coefficient is calculated from the results, which is ∼5 x 105cm-1 in solar radiation spectrum.
Citation - WoS: 47
Citation - Scopus: 51
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: 2
Citation - Scopus: 1
The Influence of the Casting Speed in Horizontal Continuous Casting of Aluminium Alloy En Aw 6082
(Springer, 2021) Obalı, Akın; Dilek, Kerem Ahmet; Akdi, Seracettin; Ürk, Deniz Kavrar; Gökelma, Mertol; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Vertical direct chill (VDC) casting is commonly used to produce slabs and billets from wrought aluminium alloys. The fact that the VDC is not a continuous process and moulds must be prepared for the next batch decreases the productivity of the process. Alternatively, horizontal direct chill (HDC) casting simplifies the process and allows a continuous production. The casting speed in the HDC casting is easier to control and can be optimized for different alloys by changing the speed. This study focuses on investigating the effects of casting speed on the macrostructure of 6082 aluminium billets with 60 mm diameter. A demo-scale casting unit was used and the casting speed was changed from 310 to 385 mm/min. Changes in surface condition, macrocracks, microporosity, and diameter of the billets were investigated. Surface quality of the billets became better with the increasing casting speed, while diameter of the billet expands. Furthermore, centreline cracks appear at the casting speed of 355 mm/min. © 2021, The Minerals, Metals & Materials Society.
Citation - Scopus: 3
Investigation of Lithium Sorption Efficiency Using Swcnt Functionalized Electrospun Fiber Mats From the Hypersaline Geothermal Brine
(Trans Tech Publications, 2018) Çelik, Aslı; Topçu, Gökhan; Isık, Tuğba; Baba, Alper; Horzum, Nesrin; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Geothermal mining from brines becomes increasingly important with the increasing demand for rare earth elements in various engineering applications. Geothermal fluids contain valuable minerals and metals such as silica, zinc, lithium, and other materials that can be processed to recover these products. Solution mining by nature is challenging because of variable composition as well as the concentration of the interfering ions, particularly calcium and magnesium, and the presence of interfering ions increases the recovery costs requiring additional steps. The aim of this study is the fabrication of single-walled carbon nanotube functionalized electrospun chitosan, poly(methyl methacrylate) (PMMA), and polyacrylonitrile (PAN) fiber mats. Effect of polymer type, dilution factor, and surface modification on the sorption of lithium (Li+) ions was investigated. The maximum sorption performance was obtained with SWCNT functionalized PAN (15 wt%) fiber mats and they have sorption percentage as 55% at diluted (1/100) brine samples.

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