MgO粉末添加对NdBaCuO籽晶的影响

Effects of MgO Powders Doping on NdBaCuO Seeds

摘要:

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

Abstract:

Top-seeded melt growth is an effective method to fabricate REBaCuO large single domain superconducting bulks. It is a key factor to choose a right seed for preparing single domain SmBaCuO bulks which has a higher melting point. Six kinds of polydomain Nd-Ba-Cu-Mg-O bulk samples doped with MgO powders of 0.2%, 0.5%, 1%, 2%, 5% and 10% (mass fraction) were prepared through spontaneous nucleation with NdBaCuO as the substrate, and then near single domain SmBaCuO bulks were successfully prepared using the NdBaCuO with 1% and 10% MgO as seeds. The effect of MgO doping content on the melting temperature of NdBaCuO precursor powders, the saturation doping content of MgO powders in NdBaCuO substrate and characteristics of Nd-Ba-Cu-Mg-O seeds were investigated by DTA, XRD and OM. Results show that MgO powder doped in NdBaCuO can significantly increase the melting temperature of NdBaCuO precursor powder. The saturation value of MgO powders doping in NdBCO is about 1%. MgO-doping between 1% and 10% does not change the basic crystal structure of Nd-123 phase