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顶部籽晶生长工艺是一种非常有效地制备REBaCuO大单畴超导块材的方法。对于具有较高熔点的SmBaCuO体系,选择合适的籽晶成为制备单畴样品的关键因素之一。本实验以NdBaCuO为基体,通过添加不同含量(0.2%,0.5%,1%,2%,5%,10%,质量分数)的MgO粉末,制备6种自发形核生长的多畴Nd-Ba-Cu-Mg-O块材样品,然后分别选用MgO含量为1%和10%的NdBaCuO为籽晶成功引导生长了近单畴的SmBaCuO块材。利用DTA、XRD和OM技术分析不同MgO添加量对NdBaCuO前驱粉末熔化温度的影响、MgO粉末在NdBaCuO基体中的饱和添加量以及Nd-Ba-Cu-Mg-O籽晶的特性。结果表明:在NdBaCuO中添加MgO粉末可以显著提高基体的融化温度;MgO粉末在NdBaCuO中的饱和添加量约为1%;在1%至10%的MgO添加范围内不会改变Nd-123的晶格类型。
The top seed growth process is a very effective method to prepare REBaCuO bulk single-domain superconductor. For the SmBaCuO system with higher melting point, selecting the appropriate seed is one of the key factors in the preparation of single-domain samples. In this experiment, six kinds of multi-domain Nd-Ba with spontaneous nucleation were prepared by adding NdBaCuO as the matrix and adding MgO powder with different content (0.2%, 0.5%, 1%, 2%, 5%, 10%, mass fraction) -Cu-Mg-O bulk samples, and then successfully selected and grown the single-domain SmBaCuO bulk with NdBaCuO with 1% and 10% MgO as the seed. The effects of different MgO loadings on the melting temperature of NdBaCuO precursors, the saturated addition of MgO powders in NdBaCuO matrix, and the properties of Nd-Ba-Cu-Mg-O seeds were analyzed by DTA, XRD and OM techniques. The results show that the addition of MgO powder to NdBaCuO can significantly increase the melting temperature of the matrix; the saturation content of MgO powder in NdBaCuO is about 1%; the Nd-123 crystal does not change in the MgO addition range of 1% to 10% Grid type