Abstract Bi2Sr2CaCu2Ox (Bi-2212) precursor powders were synthesized by the oxalate freeze drying (OFD) method. In comparison with the traditional method, the novel method could shorten the processing steps and thus improve the fabrication efficiency of precursor powder. The phase, microstructure and superconducting properties of Bi-2212 precursor powders and wires were characterized by X-ray diffraction, scanning electron microscopy and four-probe method, respectively. The thermal behavior, surface area and particle size of powders were also discussed. The results indicated that large surface area and small particle size might improve the reactivity and uniformity of powders. These properties were beneficial for the rapid and homogeneous formation of Bi-2212. High-purity crystallized Bi-2212 powders without Bi-2201 and alkaline-earth cuprates phases could be achieved. Furthermore, multi-filamentary Bi-2212 wires with OFD powders showed good microstructures without noticeable pores and large secondary particles. Therefore, high engineering critical current densities (Je) of 1619 A/mm2 and critical current densities (Jc) of 7039 A/mm2 were obtained in Bi-2212 wires at 4.2K, self field. It indicated that the oxalate freeze drying method would be a potential candidate for the mass production of high performance Bi-2212 wires.

中文翻译：

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草酸盐冷冻干燥制备的前驱体粉末向高性能 Bi-2212 线材的发展

摘要 采用草酸盐冷冻干燥（OFD）法合成了Bi2Sr2CaCu2Ox（Bi-2212）前驱体粉末。与传统方法相比，新方法可以缩短加工步骤，从而提高前驱体粉末的制备效率。Bi-2212前驱体粉末和线材的物相、微观结构和超导性能分别通过X射线衍射、扫描电子显微镜和四探针法表征。还讨论了粉末的热行为、表面积和粒度。结果表明，大表面积和小粒径可能会提高粉末的反应性和均匀性。这些特性有利于 Bi-2212 的快速均匀形成。可以实现不含 Bi-2201 和碱土铜酸盐相的高纯度结晶 Bi-2212 粉末。此外，具有 OFD 粉末的多丝 Bi-2212 线显示出良好的微观结构，没有明显的孔隙和大的二次颗粒。因此，Bi-2212 导线在 4.2K 自场下获得了 1619 A/mm2 的高工程临界电流密度 (Je) 和 7039 A/mm2 的临界电流密度 (Jc)。这表明草酸盐冷冻干燥法将成为大规模生产高性能 Bi-2212 线材的潜在候选方法。Bi-2212 线材在 4.2K 自场下获得了 1619 A/mm2 的高工程临界电流密度 (Je) 和 7039 A/mm2 的临界电流密度 (Jc)。这表明草酸盐冷冻干燥法将成为大规模生产高性能 Bi-2212 线材的潜在候选方法。Bi-2212 线材在 4.2K 自场下获得了 1619 A/mm2 的高工程临界电流密度 (Je) 和 7039 A/mm2 的临界电流密度 (Jc)。这表明草酸盐冷冻干燥法将成为大规模生产高性能 Bi-2212 线材的潜在候选方法。