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۱The Effect of Nano Al2O3 Doping on Some Properties of High temperature Superconductor Polycrystalline YBCO
نویسنده(ها): ،
اطلاعات انتشار: کنفرانس بین المللی مهندسی و علوم کاربردی، سال
تعداد صفحات: ۹
In this research we report systematically, the effect of Al2O3 nanoparticles doping on the crystal structure and superconducting properties of YBa2Cu3O7−δ (YBCO noted Y–123) polycrystalline ceramics. Samples were combined with different amounts of Al2O3 nanoparticles up to 0.3 wt%. X–ray diffraction (XRD) results revealed that the crystal lattice parameters changed and the orthorhombicity decreased slightly. SEM observations show that the grain size is reduced with increasing the content of Al2O3 in the yttrium–based superconductor (YBCO) matrix. Aluminum was considered to occupy both Y and Cu (1) sites and combined with the crystal structure. The temperature dependence of electrical resistivity ρ (T) has been measured and the effect of addition of Al2O3 nanoparticles in the paraconductivity region has been reported. By increasing of Al2O3 doping up to x = 0.3 wt%, the superconducting transition temperatures changed to 79 K and then dropped to zero at 77.10 K. The results of alumina nanoparticles addition on some superconducting parameters are discussed in relevance to the importance of Al3+ ions incorporation in Y, Cu (1) sites and oxygen stoichiometry to superconductivity in YBCO. The structural and microstructure differences between pure and alumina nanoparticles doped Y–123 are also analyzed.<\div>

۲Influence of magnetic fields on the critical temperature of bulk YBCO superconductor with nanometer–sized Al2O3 inclusions
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی پژوهش در علوم و تکنولوژی، سال
تعداد صفحات: ۱۲
The addition of nanometer alumina was found to be effective for an improvement of some superconducting properties. YBCO specimens along with different amounts of nano–sized Al2O3 were prepared using solid state reaction method. The structural characterization of all samples has been carried out by X–ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD patterns with Rietveld refinement procedure was used to characterize the samples crystal microstructure. SEM analysis revels the phases with distribution of Al2O3 nanoparticles along the YBCO grain boundaries systematically. No deviation in the structural symmetry state was found. Superconducting parameters are affected by the nanoparticle addition, and results are discussed in bearing to the structural and microstructure differences between pure Y–123 and doped Y–123. The temperature dependence of electrical resistivity ρ(T) has been measured and the effect of addition of Al2O3 nanoparticles with and without magnetic fields in the superconductivity and normal region has been reported.<\div>
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