Magnesium diboride (MgB 2 ) bulk superconductors may have practical applications as permanent magnets owing to their ability to trap larger fields than conventional ferromagnets and a transition temperature of 39 K that make them attractive for use in cryogen-free systems. Unlike the cuprate high temperature superconductors, grain boundaries in MgB 2 act as pinning sites not weak links, and so show good current carrying ability in polycrystalline samples. This enables the materials to be processed using standard ceramic processing methods which are scalable to large diameters and mass production. The maximum trapped field in bulk superconductors scales with the critical current density ( J c ) of the material as well as the radius of the sample. To obtain the highest possible J c values in MgB 2 at high fields requires the bulk materials to be fully dense but fine-grained material, and possibly with a nano-scale dist...

中文翻译：

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烧结温度对场助烧结技术制造的MgB 2块体的微观结构和超导性能的影响

由于二硼化镁（MgB 2）块状超导体具有比常规铁磁体更大的俘获磁场的能力和39 K的转变温度，因此它们可作为永磁体实际应用，并且使其在无制冷剂系统中有吸引力。与铜酸盐高温超导体不同，MgB 2中的晶界充当钉扎点而不是弱连接，因此在多晶样品中显示出良好的载流能力。这使材料可以使用可扩展至大直径和批量生产的标准陶瓷加工方法进行加工。块状超导体中的最大俘获场与材料的临界电流密度（J c）以及样品的半径成比例。