透射电子显微镜基本原理与应用2013课件电子衍射

WhatisWhatcanwelearnfromit?Whydoweseeit?Whatdeterminesthescale?WhatdeterminesthedistancesCrystallineoramorphousOrientationoftheA:[120],B:[½½单位向量a,b,c表示。苦r＝ua+vb+wc,则此点阵点的 平面数截距的倒数；米氏符号为(hkl)的面网在晶轴平面上的截距为a/h,b/k,c/l,其分数截距晶体的每个晶面都和一组平面点阵平行，可用hl)作为与该平面点阵平行的晶面的指标。但是，面网符号与晶面的米氏符号是有差别的，晶面的米氏符号中的指数总是化简为最简单的整数，相互平行的晶面的米氏符号中的指数总是相同的，它只有取向的意义，而面网nhnknlnhnknl -(hhhkk(hkhk)3al(hkhk3al)(hkhk3al3d 2dsinθ=n2dsinθ=Sinθ=λ/2d0.00370nm0.00197 O倒易点阵倒易点阵倒易点阵是厄瓦尔德(EwaldPP)在1913 c* ghklha*kb*lcghkl1/a*//a,b*//b,c*//c,a*1,b*1,c* 22dsinθ=nsind O*G2OO*sin21sindEwaldIIhkljFhklFjexp2i(hxjkyjlzj因为电子波长很小（如100kV时为0.0037nm），Ewald球半径1/杆 1x1 D11111在偏离布拉格角±Δθmax范围内，倒易杆都(hkl(hkl(hklhu+kv+lw=HH1u+K1v+L1w=0H2u+K2v+L2w=u:v:wH1K1L1H1K1H2K2L2H2K2u:v:3113113-113-1133-11-44-11 2dsin=tan2=sin2sind区成象区 立方ZrO2,a-[111b-[011c-[001],dIn(C)theringofsixdouble-diffractionspotssurroundstheAl2O3reflectionwhilein(D)thedoublediffractionspotssurroundtheFe2O3reflection.forthinforthinfilms,thediffractionspotswillalwaysbethosearrangedaroundthediffractionspotfromthelower CBEDCBED R12：R22：…：Rn利用已知晶体（点阵常数a已知）多晶衍射花样d= 为了求准确的d6363d111=HexagonalR1=3.68/4=0.92hkd1=0.482/0.92=05210R2=6.90/4=1.72500d2=10R3=7.80/4=1.9510d(nm)d(nm)hk0.191100.162110.09821？？？01hhkk(hkhk)3alcos (hkhk )(hkhk 3a2/4c2=0.29219,cos(102V1-10)=0.5/(2.16876×1)0.5=102d(A)hk2.8143102.6033002.4759101.9111101.6247111.4771101.4072201.378211hhk10001010111110201121 11-1000-1-01-3-10-2-2-2- 2236223622(02-22(20-22(-4-22(01-(-22(-1-310300210210110Φ=601201111201000 体心立方，孪生面一般为{112}，孪生方向为180转180ht2p(hpkqlr)hkt2q(hpkqlr)klt2r(hpkqlr)lht2npkt2nqlt2nr当hp+kq+lr=3n±1（n为整数）(pqr)=(111),(hkl)=(311);hp+kq+lr=5,ht1p(hpkqlr)hkt1q(hpkqlr)klt1r(hpkqlr)lhtnpktnqltnr孪晶的(hkl)倒易阵点ht=-hkt=-klt=