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- MakaleAçık Erişim2023Reclaim of Wrecked Bi-Te Based Materials In Peltier Modules In Thermopower Properties By Mechanical Milling
Yüzüak, Ercüment; Cetin, Mehmet; Yüzüak, Gizem Durak
We thoroughly evaluated the effects of various treatments on the structural and electrical properties of the two as-cast materials, “Sb-doping Bi-Te (p-type)” and “Se-doping Bi-Te (n-type)” which are frequently present in abandoned Peltier modules. To investigate the thermoelectric properties of Bi2Te3-based materials, waste alloys characterized by electrical conductivity using the hot-end method. Alloys were purified by performing arc melting on a water-cooled copper crucible in a vacuum of at least 10-3 mbar, with five times melting sessions to assure homogeneity. A single and long milling period of 144 hours is applied. After the compressing operation, the resulting discs with nanostructures were annealed for an hour at 600 K under vacuum conditions. The discs' structural properties were characterized using X-ray diffraction (XRD) and their surfaces and stoichiometries were determined using scanning electron microscopy with an energy dispersive feature. The Seebeck coefficient of the nanoparticle formed n-type Bi-Te based sample is -35.3 μV.K-1 and p-type Bi-Te based sample is 100 μV.K-1 (15% of mean error margin). It was found that a notable improvement was attained in comparison to the initial state with the addition of nanoparticles.
- MakaleAçık Erişim2020A Computational Study on Some Pyridine-Substituted-Bis-1,2,4-Triazole Derivatives and Investigation of Their Catalytic Activities
Çetın, Ahmet; Adiguzel, Ragip; Aktan, Ebru; Evren, Enes
In this work were specified catalytic activity of pyridine-substituted-bis-1,2,4-triazole (PBTT) derivative ligands 5,5′-(pyridine-2,5-diyl)bis(4-ethyl-4H-1,2,4-triazole-3-thiol) (L1) and 5,5′-(pyridine-2,5-diyl)bis(4-phenyl-4H-1,2,4-triazole-3-thiol) (L2) in biaryl synthesis in situ-reaction condition. Catalytic activities are determined in terms of conversion percentages to derivatives of biaryl of aryl bromides by GC-MS. The highest catalytic effect for L1 ligand was measured as 61% with 4-bromobenzaldehyde. Apart from catalytic activity studies, some structural properties of related ligands were discussed by computational methods. As a result, the ground state geometries, frontier molecular orbitals (FMOs) and also the maps of molecular electrostatic potential (MEP) of L1 and L2 ligands were obtained using DFT/B3LYP/6-31+G(d) calculations. Additionally, the global reactivity descriptors were reached using the FMOs calculations.
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İncele - MakaleAçık Erişim2019The effect of graphene oxide on the structural and electrical properties of yttrium ferrite based nanopowders
Aydin, Handan
In this study, Yttrium Ferrite based nano electroceramics were prepared bythe doping at various ratios of graphene oxide by the hydrothermal method.The obtained doped and undoped samples were characterized by XRD, SEM,FTIR, DTA, UV-VIS-NIR spectroscopy, temperature dependent electricalresistance changes and dielectric measurements. From the XRD results, it isobserved that the obtained samples are polycrystalline with an Orthorhombicstructure. The crystal parameters are changed with the doping of grapheneoxide. FTIR spectra indicate that the graphene oxide changes the peakintensities. This confirms the incorporation of the graphene oxide into theceramic structure. The doping of the graphene oxide changes the optical bandgaps of the samples. The dielectric constants of the samples are changed withthe graphene oxide. The DC electrical conductivity measurements confirm thesemiconducting behavior of the samples. The obtained results indicate thatthe electronic and nanostructure of the synthesized electroceramics can becontrolled by the doping of graphene oxide for electronic and energyapplications.
AtıfOpenAlex10İncele - MakaleAçık Erişim2019Fabrication and Characterization of Amorphous Semiconductor InTe Thin Film
Aydin, Cihat; Aydin, Handan; Yakuphanoglu, Fahrettin
In this study, X-ray diffraction, electrical conductivity, optical and dielectrical properties of the InTe amorphous semiconductor material have been investigated. X-ray diffraction results show that InTe sample has an amorphous structure. Temperature dependence of electrical conductivity of the sample has been investigated and the obtained results confirm that InTe is an amorphous semiconductor. The InTe sample shows photoconductivity behavior. The optical band gap and optical constants of the sample were calculated using transmittance and reflectance spectra. In the sample, the direct optical transitions take place The refractive index dispersion curve of the sample obeys the single oscillator model. The dielectrical properties of the sample have been investigated as a function of frequency and temperature. It was found that the dielectrical parameters were changed with temperature and frequency. The electrical modulus curves were used to analyze the dielectrical relaxation processes.
- MakaleAçık Erişim2018Derin Yağda Kızartma Koşulunda Zeytin Fenolikleri ile Zenginleştirilmiş Ayçiçek Yağının Stabilitesi
Atalay, Ayşe Burcu; Inanc, Ahmet Levent
Ayçiçek yağı; zeytin meyvesi, zeytin yaprağı ve pirinadan ekstrakte edilen fenolik esktraktlarla derin kızartma işlemi için ayrı ayrı zenginleştirilmiştir. Her bir kızartma işleminde patatesler, 180±5°C'de 2 L zenginleştirilmiş ve zenginleştirilmemiş (kontrol) ayçiçek kızartma yağlarında aralıklı olarak 7 defa 250 gramlık setler halinde kızartılmıştır. Yağlardaki toplam fenol içeriği (başlangıçta 200 mg kg-1 yağ), kızartma sayısının artmasıyla azalmış, ancak 5 kızartma işleminden sonra kızartma yağlarında fenolik içerik belirlenememiştir. Serbest yağ asitleri ve peroksit değerleri önemli oranda artmış ve zeytin meyve ekstraktlı yağ, 7. kızartmadan sonra en düşük serbest yağ asitleri (%0,99 oleik asit cinsinden) ve peroksit değeri (37.11 meqO2 kg-1 yağ) içermiştir. Zeytin yaprağı, zeytin meyvesi, pirina ekstraklı yağ ve kontrol örneklerinin başlangıç antioksidan aktivite kapasiteleri son kızartmadan sonra oksidasyona bağlı olarak sırasıyla yaklaşık %69, %68, %60 ve %50'ye düşmüştür.
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