SiO₂ nanoparticles addition effect on microstructure and pinning properties in YBa₂Cu₃O_y

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• 作者：M.K. Ben Salem ; E. Hannachi ; Y. Slimani ; A. Hamrita ; M. Zouaoui ; L. Bessais ; M. Ben Salem ; F. Ben Azzouz
• 关键词：YBCO superconductor ; SiO2 nanometer ; Microstructure ; Critical currents ; Flux pinning
• 刊名：Ceramics International
• 出版年：April, 2014
• 年：2014
• 卷：40
• 期：3
• 页码：4953-4962
• 全文大小：2240 K

文摘

A series of YBa₂Cu₃O_y (YBCO, Y-123) samples with small amounts (0-1 wt%) of nanosized SiO₂ particles (30 nm) are synthesized in air using a solid-state reaction route. The microstructure has been characterized by transmission and scanning electron microscopy (TEM and SEM) techniques and the magnetic field and temperature dependences of the critical current density (J_c) was calculated from the magnetization measurements and by the standard four-probe method at various temperatures. Flux pinning force density (F_p) is calculated and possibility of the pinning mechanisms prevalent in type II superconductors are investigated. X-ray diffraction analysis shows that the orthorhombic structure of YBCO is maintained. Morphology examination by SEM revealed decreases of grain size with SiO₂ addition. High zero resistance temperature value of about 90 K was maintained in YBCO with SiO₂ concentration . Compared to free added-sample, higher critical current densities were obtained for the YBCO sintered with low concentration SiO₂ (0.1 wt%) in applied magnetic field. TEM observations show the presence of columnar defects (2-3 nm in diameter) along the c-axis of YBCO and Si-rich nanophase embedded in the superconducting matrix. These defects are responsible for critical current densities improvement in the magnetic field of YBCO.