B粉对分步法制备MgB_2超导体的影响  

Effects of B Powder on the MgB_2 Superconductor Prepared by Two-Step PIT

作　　者：单迪[1,2] 王庆阳[2] 刘国庆[2] 熊晓梅[2] 李金山[1] 闫果[2] 周廉[1,2] 

机构地区：[1]西北工业大学,陕西西安710072 [2]西北有色金属研究院,陕西西安710016

出　　处：《稀有金属材料与工程》2013年第6期1278-1281,共4页Rare Metal Materials and Engineering

基　　金：国家"973"计划项目(2011CBA00104);国家自然科学基金资助项目(50877067)

摘　　要：通过分步反应法,利用晶态B粉和无定形B粉分别与Mg粉反应制备了MgB2超导体。其中分步反应法的第1步采用不同状态的B粉与Mg粉按原子比Mg:B=1:4混合,对于掺杂的样品另加5%,8%(质量分数)的SiC,采用900℃,30min或800℃,1h进行高温热处理。第2步是补充Mg粉,使Mg:B=1:2,均混的粉末经装管拉拔后进行第2步750℃,2.5h热处理。通过XRD、SEM研究样品的相组成、微观结构。采用标准四引线法测定了样品的I-V曲线。结果表明:晶态B粉与Mg粉可在第1步的热处理过程中生成大量低反应活性的MgB4。从微结构分析发现晶态B粉制备的样品具有更好的晶粒连通性,从而也得到了更稳定的I-V关系曲线。MgB2 superconductors were prepared by two-step PIT with B （crystalline or amorphous） and Mg as starting materials. The first step was mixing B （crystalline or amorphous） and Mg with the molar ratio of Mg：B=1：4. For the doping samples, 5wt% and 8wt% SiC were added to the mixture. Pressed pellets were treated at 900 ℃ for 30 min or 800 ℃ for 1 h. The second step was adding Mg to get the molar ratio of Mg：B=1：2. The tubes filled with the ground powders were treated at 750 ℃ for 2.5 h. The phase identities and the microstructure were investigated by X-ray diffraction （XRD） and Scanning Electronic Microscopy （SEM）, respectively. Voltage dependence of the current of MgB2 wire was measured by a standard four-probe method. The results demonstrate that lots of MgB4 in low energy is synthesized by crystalline B and Mg at the first step. The sample prepared from crystalline B exhibits an excellent grain connection and stable I-V characteristics.

关 键 词：MGB2超导体 分步反应法 晶态B粉 无定形B粉 

分 类 号：TM26[一般工业技术—材料科学与工程]