功能材料双语-电功能材料选编.ppt

Chapter 3　 Electrical Functional Materials;Definition: materials with special electrical properties or electromeric effect（电性效应）.;classification of electrical functional materials;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;3.1 Conductor ;crystal structure of graphite;applications of conductors;3.2 superconductor;;Definition of superconductors;Elementary properties of superconductors;;;;?critical temperature?Tc，critical magnetic field Hc， critical current Jc（临界温度、临界磁场、临界电流密度）; Josephson effect（约瑟夫森效应） ;;development of superconductor;Applications;粒子加速器;;;high-performance smart grid（智能电网）, electric power transmission（电力输送）, transformers（变压器）, power storage devices, electric motors（电动机） (e.g. for vehicle propulsion（汽车驱动）, as in maglev trains（磁悬浮列车）), magnetic levitation devices（磁悬浮装置）, fault current limiters,（故障电流限流器） and superconducting magnetic refrigeration（超导磁制冷）. ;;核聚变堆用超导线圈;Superconducting submarine（超导潜水艇）;超导磁流体推进船;maglev trains（磁悬浮列车）;superconducting electric power transmission;未来超导体汽车;寻找现实中的哈利路亚山——室温超导体;;;3.3 semiconductor;has electrical conductivity between that of a conductor such as copper and that of an insulator such as glass（σ＝10-7～104） Negative temperature coefficient（负的电阻温度系数）:?thermal conductivity?or?electrical resistivity of a semiconductor lowers with increasing temperature, which is opposite to that of a metal.;;basic concepts:; band gap, also called an energy gap （能隙）or bandgap（带隙）, is an energy range in a solid where no electron states can exist. generally refers to the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. ;;(4) Valence Band（价带） In solids, the valence band is th