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KÜÇÜK, İLKER

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KÜÇÜK

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İLKER

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  • No Thumbnail Available
    Publication
    Synthesis and characterization of graphene nanoplatelet-La₀.₇Ca₀.₃MnO₃ composites
    (Taylor & Francis, 2019-07-11) Küçük, İlker; Tekgül, Atakan; Sarlar, Kağan; Civan, Ersin; Küçük, Nil; Macan, Barış; KÜÇÜK, İLKER; Tekgul, Atakan; Sarlar, Kağan; KÜÇÜK, NİL; Macan, Barış; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; 0000-0002-8871-2357; 0000-0002-9193-4591; AAI-6808-2021; P-2124-2016; B-8159-2016; GXN-2736-2022; CCH-1761-2022; DGC-7162-2022
    La₀.₇Ca₀.₃MnO₃ perovskite and its composites with graphene nanoplatelet (GNP) were prepared using a wet chemical method. The structural, magnetic and magnetocaloric properties of La₀.₇Ca₀.3MnO₃: GNP composites were investigated to determine the effect of GNPs. The results of XRD analysis show that the synthesised powders can be almost indexed to pure phase orthorhombic La₀.₇Ca₀.₃MnO₃. The magnetic measurements demonstrate that 0.7 and 1% GNP amounts cause an increase in the Curie temperature (T-C), and for larger amounts of GNP, the T-C monotonically decreases, except for the sample with 10% GNP. The results obtained from the Arrott plots show that the magnetic phase transition of the samples transforms from the first to second order with increasing GNP amount. The changes in the magnetocaloric properties are interpreted in terms of perovskite phase formations via structural analysis. The amounts of graphene nanoplatelets in the oxide powders are correlated with the observed magnetocaloric properties. The best magnetocaloric performance with the maximum magnetic entropy change of 3.99 Jkg(-1)K(-1) and refrigeration capacity of 90 Jkg(-1) was obtained at a 2 T magnetic field.
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    Publication
    Structural, magnetic and magnetocaloric properties of Ni 54 Mn 14 Ga 27 Fe 5 :The impact of annealing time
    (Springer, 2020-04-08) Tekgül, Atakan; Sarlar, Kağan; Küçük, İlker; Tekgül, Atakan; Sarlar, Kağan; KÜÇÜK, İLKER; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; 0000-0001-6737-3838; 0000-0002-8871-2357; B-8159-2016; GXN-2736-2022; P-2124-2016; JJU-8757-2023
    The structural, magnetic and magnetocaloric properties of Ni54Mn14Ga27Fe5 Heusler alloy as a function of the annealing time have been investigated. The crystal structures have been characterized through multiphase Rietveld refinement of X-ray diffraction data. The alloys have cubic and the tetragonal structure with a mixed crystal phase at room temperature. In the magnetic measurements, the alloys exhibit the inter-martensitic and ferromagnetic-paramagnetic transition. The saturation magnetization values of the alloys decrease from 46.38 to 44.21 A m(2)kg(-1) as the annealing time is increased. The maximum magnetic entropy change is found to be as 2.8 Jkg(-1) K-1 under 2 T magnetic field.
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    Publication
    K dopant effect on La0.7KxCa0.3-xMnO3 (x=0, 0.05, 0.1) perovskite compounds: the structural, magnetic and magnetocaloric properties
    (Springer, 2020-03-23) Unlu, Cumhur Gökhan; Tekgül, Atakan; Sarlar, Kağan; Küçük, İlker; KÜÇÜK, İLKER; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Psikoloji Bölümü.; 0000-0001-6737-3838; 0000-0003-2554-5886; 0000-0002-8871-2357; B-8159-2016; GXN-2736-2022; P-2124-2016
    La0.7KxCa0.3-xMnO3 (x = 0, 0.05, 0.1) perovskites were prepared by sol-gel method. The K-doped effect was determined by the structural, magnetic, and magnetocaloric properties of the compounds. In the crystal structure of K-doped La0.7Ca0.3MnO3, Mn-O-Mn bond angle slightly increases with K addition. The transition shifts the range of 270-320 K when the K is added in La0.7Ca0.3MnO3. The Curie temperature increases from 251 to 288 K with increasing K amount. The maximum magnetic entropy change was found to be 2.7 J kg(-1) K-1 at 283 K under a magnetic field change of 2 T for the La0.7K0.05Ca0.25MnO3. The relative cooling powers (RCPs) in the La0.7KxCa0.3-xMnO3 (x = 0, 0.05, 0.1) samples were calculated to be 103, 133 and 88 J kg(-1), respectively.
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    Publication
    Effect of gd substitution on the structural, magnetic, and magnetocaloric properties of Fe68Tb5B23Nb4 metallic glass
    (Korean Magnetics Soc, 2019-03-01) Civan, Ersin; Sarlar, Kağan; Küçük, İlker; KÜÇÜK, İLKER; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Anabilim Dalı.; 0000-0002-8871-2357; B-8159-2016; GXN-2736-2022; FJG-9926-2022
    The effects of adding Gd on the Curie temperature (T-c), glass-forming ability (GFA), and magnetocaloric effect (MCE) were studied in Fe68-x ,GdxTb5B23Nb4 (x = 0, 2, and 6) glassy alloys prepared by suction casting. It was shown that when Gd content was exchanged with Fe partially for x = 2, GFA was increased, whereas for x = 6, adding Gd content has reduced the GFA and amorphous structure could not be obtained. Critical diameter was found to be 3 mm for Fe66Gd2Tb5B23Nb4 bulk metallic glass (BMG). By exchanging Gd with Fe partially, T c could effectively be tuned in a quite broad temperature interval from 487 K (x = 0) to 380 K (x = 6) for which amorphous structure could not be obtained. Maximum magnetic entropy change (-Delta S-M)(max) values were found to be 1.16, 0.84 Jkg(-1)K(-1), and 0.54 Jkg(-1)K(-1) as well as, refrigeration capacity (RC) values were obtained as 116 J/kg, 84.84 J/kg, and 40.50 J/kg under a low field change of 2 T for x = 0, 2, and 6, respectively. Although T c was shifted to lower temperatures by exchanging Fe with Gd partially, -(Delta S-M)(max )decreased almost half of the base alloy and RC decreased approximately 1/3 of the base alloy.
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    Publication
    Structural, optical and magnetic properties of α-Fe2O3-SiO2 and Dy2O3-SiO2 composites produced by a facile method
    (Springer, 2019-10-23) Kendir, Esra; Yaltkaya, Serafettin; Küçük, İlker; KÜÇÜK, İLKER; Tekgül, Atakan; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi; 0000-0002-6728-5640; 0000-0001-6737-3838; P-2124-2016; Q-2355-2016
    We prepared SiO2, Fe2O3-SiO2, and Dy2O3-SiO2 composites by an enhanced method and reported the result of their structural, optical and magnetic properties. In the x-ray diffraction results of the Fe2O3-SiO2, Fe2O3 and the SiO2 it is evident that these composites are crystallized in rhombohedral and trigonal structures, respectively. In the Dy2O3-SiO2 composite, SiO2 transforms into a trigonal structure with the addition of Dy. The absorption bands belong to Fe2O3, and Dy2O3 were obtained using the Fourier transform infrared spectra. In ultraviolet-visible spectra, the photocatalytic properties of Fe2O3-SiO2 and Dy2O3-SiO2 were determined as a function of time at room temperature. Maximum transmittance change at 800 nm was 75% and 40% for composites Fe2O3-SiO2, and Dy2O3-SiO2, respectively. The photocatalytic property of Dy2O3-SiO2 composite increases gradually from short to long in the wavelength region where it exhibits a maximum value in the visible region. In magnetic measurements, a weak ferromagnetic behavior was observed in the Fe2O3-SiO2, while Dy2O3-SiO2 exhibited paramagnetic behavior as expected. The saturation and coercivity values for Fe2O3-SiO2 were found to be 0.15 Am-2 kg(-1) and 40 mT, respectively.