Al改性MgB_(2)材料与金属界面特性及其超导性能研究

Superconducting performance and interface characteristics with metals of Al modified MgB_(2) materials

针对MgB_(2)超导材料用于液氢液位传感器的临界转变温度与液氢液化温度差异大和原始粉末与金属护套界面反应导致测量控制难的问题,研究了降低MgB_(2)临界转变温度的改性技术,以及改性后粉末与金属护套Fe、Monel反应产物及退火温度对其超导转变宽度的影响。结果表明,当掺杂量x=0.15时,Mg_(1-x)Al_xB_(2)多晶样品的临界转变温度为30 K左右,满足液氢液位传感器使用环境。金属护套Fe、Monel与前驱体粉末Mg、Al之间都有不同程度的扩散界面发生,Fe金属护套样品扩散层厚度较小,大约为25μm,更适合于Al掺杂MgB2超导线材的制备护套材料。不同退火温度下的带金属护套的Fe、Monel改性MgB_(2)样品仍具有明显的超导转变,且超导转变温度满足液氢液位计使用环境。

The use of MgB_(2) superconducting material in liquid hydrogen level sensors has problems with significant differences in critical transition temperature and liquid hydrogen liquefaction temperature and interface reactions between the original powder and metal sheath.These problems make it difficult to measure and control the liquid hydrogen level sensors.We studied the Al doping modification technology to reduce the critical transition temperature of MgB_(2).And we studied the effects of the interface reaction between the original powder and the metal sheath Fe,Monel and annealing temperature on its superconducting transition width.The results show that when the doping amount x=0.15,the critical transition temperature of Mg_(1-x) Al x B_(2) polycrystalline sample is about 30 K,which meets the requirements for the use of liquid hydrogen level sensors.There is a diffusion interface between the metal sheath Fe,Monel and the precursor powder Mg,Al.The diffusion layer thickness of the Fe metal sheath sample is relatively small,approximately 25μm.So,the Fe metal sheath is more suitable for preparing sheath materials for Al doped MgB_(2) superconducting wires.Fe and Monel modified MgB_(2) samples with metal sheaths at different annealing temperatures still exhibit significant superconducting transitions,and the superconducting transition temperature meets the operating environment of liquid hydrogen level sensors.