tailieunhanh - Bài giảng Vật liệu học: Chương 6 - TS. Nguyễn Văn Dũng

Bài giảng "Vật liệu học - Chương 6: Electrical properties" cung cấp cho người học các kiến thức về Ohm’s law, energy levels of an isolated atom, conduction & electron transport, charge carriers in insulators and semiconductors, energy bands, the mass action law, . Mời các bạn cùng tham khảo. | Chapter 6 Electrical properties Ohm s law 1 https tailieudientucntt Ohm s Law V IR voltage drop volts J C resistance Ohms C Coulomb current amps C s Resistivity -- a material property that is independent of sample size and geometry surface area RA of current flow l current flow path length Conductivity 1 2 https tailieudientucntt Which will have the greater resistance 2 2 8 D R1 D 2 D 2 2 R1 2D R2 2D D 2 2 8 2 Analogous to flow of water in a pipe Resistance depends on sample geometry and size. 3 https tailieudientucntt Further definitions J E 5 https tailieudientucntt 6 https tailieudientucntt 7 https tailieudientucntt CONDUCTIVITY COMPARISON Room temperature values Ohm-m -1 m -1 S m-1 METALS conductors CERAMICS -10 Silver x 10 7 Soda-lime glass 10 -10-11 Copper x 10 7 Concrete 10 -9 Iron x 10 7 Aluminum oxide 9 https tailieudientucntt EXAMPLE What is the minimum diameter D of the wire so that V lt V x 107 Ohm-m -1 100 m Cu wire - I A V 100 m lt V V R A D 2 A I 4 x 107 Ohm-m -1 Solve to get D gt mm 10 https tailieudientucntt Energy levels of an isolated atom 11 https tailieudientucntt 12 https tailieudientucntt 13 https tailieudientucntt ELECTRON ENERGY BAND STRUCTURES 14 https tailieudientucntt BAND STRUCTURE REPRESENTATION 15 https tailieudientucntt 16 https tailieudientucntt 2003 Brooks Cole a division of Thomson Learning Inc. Thomson Learning is a trademark used herein under license. Metals Insulators Semiconductors 17 https tailieudientucntt CONDUCTION amp ELECTRON TRANSPORT Metals Conductors -- for .