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    Characterization of Sm0.3Ce0.2Sr0.5MnO3 as an electron-doped system: structural, electrical, and dielectric properties
    (Springer, 2024) Koc, N. Soylu; Gokcen, M.; Varilci, A.; Altintas, S. P.
    A novel samarium-based cerium-doped ceramic manganite of Sm0.3Ce0.2Sr0.5MnO3 (SCSMO) was prepared via the high-temperature solid-state reaction method. The experimental investigation focused on exploring the crystallographic, morphological, and dielectric characteristics of the perovskite ceramic. Rietveld's refinements of X-ray diffraction patterns confirm that a single-phase orthorhombic crystal structure with the space group of Pnma (62) without any detectable impurity phase is obtained for ceramic perovskite. Based on X-ray data, the average size of crystallites was determined to be 80.9 nm using the Williamson-Hall method. The surface morphology analysis through scanning electron microscopy (SEM) revealed distinct grains with an average size of 8.22 mu m. The study utilized dielectric and impedance spectroscopy at different temperatures and frequencies to thoroughly examine the electrical parameters of SCSMO. Through this analysis, a relationship between the conduction mechanism and structural qualities was established.
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    The effect of cooling rates on properties of Bi1.7Pb0.35Sr1.9Ca2.1Cu3Oy superconductors produced by solid-state reaction method
    (Elsevier Science Bv, 2007) Öztürk, Özgür; Yeğen, D.; Yılmazlar, M.; Varilci, A.; Terzioğlu, C.
    We have investigated the effect of the cooling rates in the Bi-2223 superconducting samples prepared by standard solid-state reaction method using electrical resistivity, transport critical current density, and XRD (X-ray diffraction) measurements. We estimated the transition temperature values from the DC resistivity measurements. We observed that transition temperature, T-c, and transport critical current density, J(c)(trans), depend on the cooling rates of the samples. They both increase with increasing cooling rates. We estimated the peak temperature, T-P, from our previous ac susceptibility measurements. The pinning force density increased with increasing the cooling rate. XRD patterns are used to calculate lattice parameter c and obtain information about Bi-2223 phase ratio. (c) 2006 Elsevier B.V. All rights reserved.
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    Effect Y substitution on the microstructure, transport and magnetic proprieties of Bi2Sr2Ca1Cu2O8+? superconducting ceramics
    (Walter de Gruyter GmbH, 2016) Menassel, S.; Mosbah, M.-F.; Boudjadja, Y.; Altintas, S.P.; Varilci, A.; Terzioglu, C.
    In high Tc superconductors (HTSC) the activation energy gives information about the pinning properties of a sample under applied magnetic field. Pinning of vortices determines the critical current density Jc which is of great importance for practical applications of HTSC. Instead of magnetic measurements, the activation energy may be calculated from resistivity measurements realized under magnetic field. This kind of measurement has been made in this work for yttrium doped samples of Bi2Sr2CaCu2O8+d (Bi-2212) for different values of applied magnetic field. Samples of Bi2Sr2Ca1-xYxCu2O8+d (x = 0, 0.025, 0.1, 0.25) were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray. The measurements of resistivity were made using a classical four probe method and DC current. The magnetic field was applied with a constant amplitude of 0 T, 1 T, 2 T and 3 T. The obtained results show that the activation energy decreases with introduction of yttrium, but has a relative maximum when x is equal 0.1. The decrease of the activation energy is explained by the granular nature of the samples which promotes 3D transition to 2D of the vortex lattice. © 2016 Wroclaw University of Technology.