NiFe2O4纳米粒子掺杂对单畴YBCO超导块材性能的影响  

Influence of NiFe2O4 nanoparticle doping on properties of single-domain YBCO bulk superconductors

作　　者：李国政 陈超 Li Guo-Zheng;Chen Chao(College of Physics and Materials Science,Tianjin Normal University,Tianjin 300387,China)

机构地区：[1]天津师范大学物理与材料科学学院,天津300387

出　　处：《物理学报》2020年第23期230-236,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51872199)资助的课题.

摘　　要：采用一种新型的顶部籽晶熔渗生长(TSIG)工艺制备了铁酸镍(NiFe2O4,NFO)纳米粒子掺杂的YBCO超导块材,并对其生长形貌、微观结构、超导性能进行了研究.结果表明,在低掺杂量下,YBCO单畴体的正常生长不会受NFO掺杂的影响,但是在高掺杂水平下样品边缘开始出现明显的随机成核.磁悬浮力性能测试结果表明,随着NFO掺杂量的增加,样品的最大磁悬浮力先增大后减小,掺杂重量百分比为0.2%的样品表现出最大的磁悬浮力(33.93N).低温磁性测试结果表明,随着NFO掺杂量的增加,样品的Tc值逐渐降低,而且超导转变宽度(ΔTc)也逐渐变宽.最佳掺杂下(重量百分比为0.2%)样品的零场Jc值为8.68×104 A/cm2,比未掺杂样品提高了31%.电子探针微区分析(EPMA)结果表明,YBCO体系中掺杂的纳米NFO在热处理过程中发生了分解,而溶解出的Ni和Fe离子最终以元素替代的方式存在于YBCO块材内,这可以在超导基体中引入晶格畸变和弱超导区作为有效的磁通钉扎中心,从而提高样品的超导性能.NiFe2O4(NFO) nanoparticle doped YBCO bulk superconductors are fabricated by using a novel top-seed infiltration growth(TSIG) technique.The growth morphology,microstructure and superconducting properties are investigated.The results show that at low doping levels,the normal growth of YBCO single domain is not affected by the NFO doping,but at high doping levels,obvious random nucleation appears at the edge of the sample.The measurement of levitation force indicates that the maximum levitation force on the sample first increases and then decreases with the increase of the NFO doping amount,and the largest levitation force is obtained to be 33.93 N for the sample with a doping level of 0.2%(weight percent).Low-temperature magnetization measurement shows that the YBCO sample exhibits that Tc value decreases with NFO amount increasing,and the superconducting transition width(ΔTc) also broadens gradually.The sample with the optimal doping(0.2% weight percent) presents an enhanced zero-field Jc value of 8.68×104 A/cm2,which is 31% higher than the sample without dopant.In addition,a more obvious secondary peak of 4.37× 104 A/cm2 at a field of 1 T is observed for the 0.2 wt.% NFO doped sample,which indicates the existence of enhanced δTc pinning in the bulk.The SEM measurement shows that two types of particles are trapped in the Y-123 matrix for YBCO sample doped with 0.2% weight percent NFO:one is the large particle with a size mainly ranging from 0.5μm to 2.0μm,and the other is small nano-inclusion mainly ranging from dozens of nanometers to about several hundreds of nanometers.Such a microstructure is very similar to the microstructure of the undoped sample we reported earlier.So whether the NFO nanoparticles exist in the microstructure cannot be judged just from the morphology of the nano-inclusions.The electron probe microarea analysis(EPMA) result shows that different concentration distributions of Ni and Fe elements are observed in the sample doped with0.2% weight percent NFO,which indicates the separation of

关 键 词：单畴YBCO 顶部籽晶熔渗生长 NIFE2O4 纳米粒子掺杂 超导性能 

分 类 号：O511.3[一般工业技术—材料科学与工程]