Papers by Author: X.H. Ma

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Authors: Y.L. Jiao, L. Xiao, M.H. Zheng, X.H. Ma, Xin Tai Su, Qing Zhi Yan
Abstract: GdBaCuO bulk superconductors from precursors of Gd123 and ultrafine Gd211 powder have been fabricated by melt-textured-growth method in air. The ultrafine Gd211 powder was synthesized by an improved Pechini method. It was found that the lower temperature of synthesizing ultrafine Gd211 powder, the higher peritectic reaction temperature of GdBaCuO bulk superconductors. Jc reaches 4.7×104 A/cm2 at 77 K and self-field for ultrafine Gd211 starting particles with 0.2μm in diameter, and higher compared to larger Gd211 starting particles fabricated by solid state reaction. However, a large secondary peak effect did not appeared at Jc-B curves. ,
Authors: X.H. Ma, Xin Tai Su, Qing Zhi Yan, Y.L. Jiao, L. Xiao, Chang Chun Ge
Abstract: This paper describes the details on synthesizing nanocrystalline Gd2BaCuO5 (Gd211) using low-temperature combustion synthesis(LCS). The morphology and structure of the powders are characterized by field emission scanning electron microscopy (FESEM) and XRD. The size of obtained powders by this method calcined at 800 C is about 100nm, which is much smaller than the powders synthesizing by conventional solid state route. Besides, the Gd211 powders synthesizing by LCS have a low calcination temperature with a high-purity. The microstructure of melt-textured samples is also observed by FESEM, the result shows that the size of Gd211 particles trapped in GdBa2Cu3O7 (Gd123) matrix could be refined by using ultrafine Gd211 powder as a precursor. The refined Gd211 particles with a good distribution resulted in the improvement of Jc values in this system.
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