Yazar "Ak, Fermin" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Determination of Electrical Properties and Microhardness in Fe-Mn-Ti-Sn Heusler Composition(Niyazi BULUT, 2025) Arıkan, Mehtap Payveren; Ak, Fermin; Saatçi, BuketFe-Mn-Ti-Sn alloy is known as both Heusler and shape memory alloy and electrical conductivity and microhardness studies related to this alloy are insufficient. In the study, Fe-Mn-Ti-Sn Heusler [Fe2-xMnxTiSn (0≤x≤2)] alloy was selected Fe2TiSn, Fe1.5Mn0.5TiSn, FeMnTiSn, Fe0.5Mn1.5TiSn, Mn2TiSn components were obtained in these ratios for the first time using arc melter melting furnace. Temperature dependent electrical measurements of the obtained samples were determined by four point probe method (FPPT). The electrical resistance values of the samples at 330K were obtained as 0.14-2.25x10-6 (m) and 0.02-0.49 x10-6 (m) at 750 K. In addition, the temperature coefficient of electrical resistivity value was calculated as (0.03-1.29)x (10-3 K-1). Phases belonging to each composition were determined by examining the XRD peaks. Microstructures of the samples were obtained by SEM, EDX and MAPPING images. Finally, the composition-dependent microhardness measurements of the samples were determined using the Vickers hardness test and the average microhardness values obtained were measured as 481-716 HV0.5.Öğe Determination of Microstructure, Electrical Properties and Microhardness Values of Ni-Mn-Cr-Sn Heusler Alloy(Niyazi BULUT, 2025) Ak, Fermin; Arıkan, Mehtap Payveren; Saatçi, Buket; Ari, MehmetIn this study, Ni-Mn-Cr-Sn Heusler [Ni2(Mn1-xCrx)Sn (x=0, 0.25, 0.5, 0.75 and 1, (0≤x≤1)] alloys were investigated. The determined powder samples were compressed under pressure and turned into pellets and then melted in an arc melting furnace to provide the desired Heusler conditions. After XRD analysis was performed on the samples obtained after the process, SEM, EDX and MAPPING images were taken. Phases belonging to each composition were determined by examining the XRD peaks. A backscattered detector was used in SEM, EDX and MAPPING analyses of the samples. Finally, the microhardness measurements of the samples, depending on the composition, were determined using the Vickers hardness test, and the average microhardness values obtained were measured as 486.6-805.5HV0.3. Temperature-dependent electrical measurements of the obtained samples were determined by four-point probe method (FPPT). The electrical resistance values of the samples at 320K were obtained as 0.12-400.72x10-6 (m) and 0.01-0.62 x10-6 (m) at 900 K. In addition, the temperature coefficient of electrical resistivity value (TCR) was calculated as (1.47-3.16)x (10-3 K-1).Öğe Key role of central antimony in magnetization of Ni 0.5 Co 1.5 MnSb quaternary Heusler alloy revealed by comparison between theory and experiment(Elsevier, 2019) Şarlı, Numan; Ak, Fermin; Özdemir, Evren Görkem; Saatçi, Buket; Merdan, ZiyaTemperature dependent magnetization of Ni0.5Co1.5MnSb quaternary Heusler alloy is investigated both theoretically (m-T) and experimentally (M-T). According to the XRD data, the crystal structure of Ni0.5Co1.5MnSb is compatible with the cubic crystal structure with space group symmetry Fm-3m and the lattice parameter of a?=?5.968?Å. Experimental M-T curve is obtained at H?=?1?T. The Curie temperature is obtained at about TCEXP?=?538.3?K. We also use effective field theory (EFT) developed by Kaneyoshi to model and investigate the m-T properties of Ni0.5Co1.5MnSb. We find that the theoretical m-T and experimental M-T results overlap at low temperatures (T??100?K). In particular, the theoretical mSb3-T curve of the central Sb3 atom is much closer to the experimental M-T curve of Ni0.5Co1.5MnSb than that of the other components (mMn1, mMn2, mMn3, mSb1, mSb2, mNi and mCo). Therefore, we strongly propose that one needs to pay close attention to the magnetization of the central atom especially in the lattice of Heusler alloys in both their predictive and experimental studies.Öğe Molecular Structure, Geometry Properties, HOMO-LUMO, and MEP Analysis of Acrylic Acid Based on DFT Calculations(Niyazi BULUT, 2023) Kebiroglu, Hanifi; Ak, Fermin[Abstract Not Available]Öğe Potential Benefits and Opportunities of AI-Enabled Software Programs for Opticians: A study in Türkiye(Niyazi BULUT, 2024) Ak, Fermin; Kebiroglu, Mehmet Hanifi[Abstract Not Available]Öğe Ru-486 ve Türevlerinin Optimize Edilmiş Durum Yoğunluğu (DOS) Analizi, UV-Görünür Bölge Spektroskopisi, NMR Spektroskopisi ve Moleküler Elektrostatik Potansiyel (MEP) Haritalaması Üzerine İnceleme(2025) Kebiroğlu, Mehmet Hanifi; Ak, FerminMisoprostol ile birlikte kullanıldığında, Ru-486 (Mifepriston) erken gebelik kaybının (EGK) yönetiminde son derece etkili ve invaziv olmayan bir seçenek sunarak cerrahi müdahalelere uygun bir alternatif sağlar. Bu çalışmada, Ru-486 molekülü ve türevlerinin (CH2CH3, CH3, F) yapısal ve spektroskopik özelliklerini hesaplamak için kuantum hesaplamalı kimya yöntemleri kullanılmıştır. Molekül, B3LYP/6-31G baz seti ile Yoğunluk Fonksiyonel Teorisi (DFT/B3LYP) kullanılarak optimize edilmiştir. Durum Yoğunluğu (DOS) Analizi, UV-Görünür Bölge Spektroskopisi, NMR Spektroskopisi ve Moleküler Elektrostatik Potansiyel (MEP) Haritalaması incelenmiştir. HOMO-LUMO bant aralıkları 3,19–4,02 eV arasında belirlenen bileşiğin FT-IR spektrumunda temel titreşim pikleri 3076 cm⁻¹ değerinde gözlenmiş olup, UV-Vis analizinde maksimum absorpsiyon 408 nm dalga boyunda tespit edilmiştir. Ayrıca, karakterizasyon yöntemlerinin temel teorisi üzerine bir tartışma da dahil edilmiştir.Öğe Semiconducting character analysis of RhY2O4 oxide spinel via GGA, GGA plus mBJ, and GGA plus U approximations(Indian Assoc Cultivation Science, 2025) Ak, Fermin; Ozdemir, Evren Goerkem; Aliabad, Hossein A. RahnamayeThe semiconducting character of RhY2O4 oxide spinel was investigated using first-principles approximations. As a result of the optimization curve, RhY2O4 was obtained as a ferromagnet with an equilibrium lattice parameter of 9.46 & Aring; with the help of the GGA approximation. When U = 1, 2, 3, and 4 eV were used, the lattice parameters were obtained as 9.49 & Aring;, 9.52 & Aring;, 9.55 & Aring;, and 9.58 & Aring;, respectively. The GGA approximation yielded the band gap values with the lowest semiconductor character, measuring 0.352 eV for the majority electron spin and 0.134 eV for the minority electron spin. Both direct and indirect band gaps were observed in the majority and minority electron spins. Elastic calculations confirmed the elastic stability of RhY2O4. Furthermore, the Debye temperature was determined to be 480.942 K at 0 GPa pressure. Poisson's and B/G ratios were obtained at this pressure as 0.278 and 1.92, respectively. According to these results, RhY2O4 spinel is ductile. However, with increasing pressure, brittleness properties begin at about 10 GPa. RhY2O4 has a total magnetic moment of 6.000 mu B/f.u. RhY2O4 is a promising candidate for semiconductor applications, characterized by advantageous elastic, magnetic, and electronic properties.Öğe Structural and magnetic characterisation of Co substituted Ni2MnSb Heusler alloy: effect of cobalt substitution on magnetism and Curie temperature(Taylor and Francis Ltd., 2021) Öz, Erdinç; Ak, Fermin; Saatci, BuketIn this study, Ni2-xCo x MnSb full-Heusler alloys (1.00 ? x ? 1.75) were prepared by arc melting process, and examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and SQUID. The L21 crystal structure of the synthesised Heusler alloy was confirmed by XRD patterns, and it was observed that the use of Co instead of Ni caused a decrease in the interatomic distance. The magnetisation results revealed that all samples show ferromagnetic (FM) behaviour, and substitution Co for Ni leads to increasing FM interactions in the samples. The calculated magnetic moment per formula unit increase from 4.38 µB(x =1) to 5.17 µB (x =1.75). On the other hand, the increase in FM interaction caused an increase in ferromagnetic-paramagnetic (PM) phase transition (T C) temperatures from 513 (x =1) to 568 K (x =1.75). The ability to control the Curie temperature with Co substitution makes these alloys suitable candidates for future spintronics and magnetoelectronic applications.Öğe Structural and magnetic properties of Ni2-xCoxMnSb (x: 0.00, 0.25, 0.50 and 1.00) Heusler alloys: The relationship between Curie temperature and lattice parameter(Elsevier, 2019) Ak, Fermin; Öz, Erdinç; Saatçi, BuketNi2-xCoxMnSb Heusler alloys were fabricated by arc melting process. The endothermic/exothermic reactions with increasing temperature were determined by DTA analysis and it was found that the chancing Co concentration in the system causes the change in the reaction temperatures. The temperature dependence of the magnetization from base temperature to 600?K, a crucial value for the Curie temperature, and lattice parameters of the samples were determined. It was suggested that increasing Co in the samples causes the change of the grain formation and the increasing Co concentration in the system also causes the change of the Curie temperature values with decreased the lattice parameters.
