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    Reveal of relationship between microscopy architecture and mechanical performance of Y/Bi substituted Bi-2212 engineering ceramics
    (Wiley, 2024) Yilmaz, Tolgahan; Kurtul, Gulnur; Ulgen, Asaf Tolga; Erdem, Umit; Mercan, Ali; Turgay, Tahsin; Yildirim, Gurcan
    This study aims to find out how the crystallinity quality, surface morphology, and mechanical performances change with the substitution of yttrium (Y) for bismuth (Bi) impurity within molar ratios of 0.00 <= x <= 0.12 in the Bi2.0-xYxSr2.0Ca1.1Cu2.0Oy (Bi-2212) cuprates to reveal the dependence of micro surface topology on the substitution mechanism and achieve a strong relation between the impurity ions and crystallization mechanism. The materials are prepared by ceramic method. It is found that all the experimental findings improve remarkably with increasing yttrium impurity molar ratio of x = 0.01. Scanning electron microscopy (SEM) images indicate that the optimum Y ions strengthen the formation of flaky adjacent stacked layers due to the changes of thermal expansion, vibration amplitude of atoms, heat capacitance, reaction kinetics, activation energy, nucleation temperature, thermodynamic stability, and intermolecular forces. Besides, new engineering novel compound produced by optimum Y ions presents the best crystallinity quality, uniform surface view, greatest coupling interaction between grains, largest particle size distributions/orientations, and densest/smoothest surface morphology. Hardness measurement results totally support the surface morphology view. Moreover, mechanical design properties and durability of the tetragonal phase improve significantly with increasing replacement level of x = 0.01 due to the induction of new surface residual compressive stress areas, slip systems, and chemical bonding between the foreign and host atoms. Besides, the same sample exhibits the maximum strength and minimum sensitivity to loads depending on reduction of stored internal strain energy and degree of granularity. Consequently, cracks tend to propagate predominantly within the transcrystalline regions. Furthermore, each material investigated exhibits the characteristic behavior of the indentation size effect. In summary, the optimum Y-doped Bi-2212 sample paves the way for the expanded use of engineering ceramics across various applications based on the enhanced service life.Research Highlights The presence of the optimum yttrium impurity significantly decreases the Ea value. As the Y/Bi replacement increases up to the molar substitution level of x = 0.01, the mechanical design properties and durability of the tetragonal phase enhance significantly. Mystery of the change in the mechanical performance features of the Y-doped Bi-2212 advanced ceramic compound against the applied test loads is related to the microscopy architecture.image
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    Support of polaronic states and charge carrier concentrations of YBa2Cu3O7-y ceramics by oxygen and Mn2O3 impurity
    (Wiley, 2024) Kurtul, Gulnur; Yildirim, Gurcan; Turgay, Tahsin; Terzioglu, C.
    The influence of oxygen and Mn2O3 impurity addition intervals 0.01 <= x <= 0.30 on the basic electrical conductivity, stabilization, crystallinity quality, grain boundary couplings, structural, orbital hybridization mechanisms, and superconducting properties of YBa2Cu3O7-yMnx ceramics has extensively been analyzed by electrical resistivity, X-ray diffraction investigations, and related theoretical results. It has been found that there is a strong link between the production conditions and fundamental characteristic features. All the results deduced have enabled us to discuss the variation of electron-electron and electron-phonon interactions, order parameter for super-electrons and cooper-pairs, organization of Cu-O coordination, homogeneities of oxidation states, microscopic structural problems, electronic density states, and grain boundary couplings between the adjacent layers in the YBa2Cu3O7-y ceramics. Similarly, we have discussed the change in the formation of pairing mechanisms and bipolarons in the polarizable lattices in the microdomain clusters. The results have shown that both the presence of oxygen and optimum manganese impurity of x = 0.07 led to the enhancement in the fundamental characteristic features related to the basic physical, quantum mechanical, and thermodynamics features. Thus, the material produced at the most ideal conditions has exhibited the best orthorhombic crystal structure with the distortion degree of 6.419 x 10(-3), paring mechanism, and crystallinity quality due to the development of orthorhombicity and oxygen ordering degree. Namely, the addition of optimum manganese impurity has organized the Cu-O coordination and stabilized the crystal structure as much as possible. Numerically, the sample prepared with x = 0.07 Mn ions has displayed the largest crystallite size, c-axis length, residual resistivity ratio, onset, and offset critical temperatures of 10.977, 11.723 & Aring;, 73 nm, 98.320 K, and 100.504 K, respectively. Conversely, the same material has demonstrated the smallest oxygen ordering degree of 6.714, strain of 44.015 x 10(-3), and a- and b-axis lengths of 3.792 and 3.841 & Aring;. On the other hand, the oxygen-free annealing condition and excess manganese impurity have completely damaged the whole mechanism because of the phase transition from orthorhombic to tetragonal (structural O-T transition) crystal structure. To sum up, the oxygen and optimum manganese impurity have encouraged the YBa2Cu3O7-y superconductors to use in much more application fields.