【正文】 maglev trains（磁懸浮列車） 近日，國家“十三五”重點研發(fā)計劃 《 現(xiàn)代軌道交通專項 》 啟動時速 600公里高速磁懸浮交通和時速 200公里中速磁浮交通研發(fā)項目 superconducting electric power transmission 未來超導體汽車 尋找現(xiàn)實中的哈利路亞山 ——室溫超導體 semiconductor ?has electrical conductivity between that of a conductor such as copper and that of an insulator such as glass（ σ＝ 107～ 104） ?Negative temperature coefficient （ 負 的 電 阻 溫 度 系數(shù) ） : thermal conductivity or electrical resistivity of a semiconductor lowers with increasing temperature, which is opposite to that of a metal. semiconductor useful properties: ?passing current more easily in one direction than the other。 ? it can be alloyed to ternary and quaternary positions, with adjustable band gap width, allowing light emission at chosen wavelengths, and allowing . matching to wavelengths with lowest losses in optical fibers。Chapter 3 Electrical Functional Materials Definition: materials with special electrical properties or electromeric effect（ 電性效應 ） . Semiconductor materials Superconducting materials Conductive materials Electrical Functional Materials classification of electrical functional materials ? based on the conductive mechanism： electron conduction material and ionic conduction material. ? electron conduction material: semiconductor, conductor and superconductor ： 107 106 105 104 103 102 101 100 101 102 103 104 105 106 conductivity σ S/m insulator semiconductor conductor superconductor： σ→ ∞ ?the movement of an ion from one site to another through defects in the crystal lattice of a solid or aqueous solution, ? so the conductivity is smaller because the travelling speed of ion is slower than electron, ? the conductivity is no more than 102 S/m ， and usually smaller than 100 S/m ionic conduction material Conductor （ 1） metal. the conductivity is 107~108 S/m。 ? GaAs can be also grown in a semiinsulating半絕緣 form, which is suitable as a latticematching 晶格匹配 insulating substrate for GaAs devices. ? Conversely, silicon is robust強健的 , cheap, and easy to process, whereas GaAs is brittle脆的 and expensive, and insulation layers can not be created by just growing an oxide layer。 or higher than the critical magic field Hc, critical current Jc ,the regions separateed by Tc、 Hc， Jc. Josephson effect（約瑟夫森效應） The Josephson effect is the phenomenon of supercurrent—. a current that flows indefinitely（ 無限期的 ） long without any voltage applied—across a device known as a Josephson junction (JJ), which consists of two superconductors coupled by a weak link. ? The weak link can consist of a thin insulating barrier (known as a superconductor–insulator–superconductor junction, or SIS), a sh