電子顯微鏡第三章衍射花樣分析

1、單晶電子衍射花樣的產(chǎn)生及其幾何特征o*r*r*ss02o*(h1k1l1)(h2k2l2)(h3k3l3)o*dlr1*)(rlrdd1tddt1t1t球盤針狀d1d1厄瓦爾德球薄晶的倒易點(diǎn)拉長(zhǎng)為倒易桿產(chǎn)生衍射o*goh1k1l1h2k2l2h3k3l3h4k4l4r1r2r3r4o9r12:r22:r32:.= 1/d12: 1/d22: 1/d32: =n1:n2:n3 :; (n=h2+k2+l2)222222212121212121coslkhlkhl lkkhhh1k1l1h2k2l2h3k3l3h4k4l4r1r2r3r4o 由矢量疊加原理，得到所有斑點(diǎn)的指數(shù)（hkl);根據(jù)斑點(diǎn)指

2、數(shù)計(jì)算r之間的夾角，與測(cè)量結(jié)果進(jìn)行對(duì)比驗(yàn)證。如果結(jié)果吻合，標(biāo)定正確；反之重新嘗試h,k,l，重復(fù)上述過程。h1k1l1h2k2l2h3k3l3h4k4l4r1r2r3r4oh1k1l1h2k2l2h3k3l3h4k4l4r1r2r3r4o00222111wlvkuhwlvkuh221122112211:khkhhlhllklkwvuu=k1l2-k2l1 v=l1h2-l2h1 w=h1k2-h2k1 例1 低碳合金鋼基體的電子衍射花樣000acdb000acdb110200211411e011211411000002004acdbe2 例2 al單晶(fcc)衍射花樣，k15.21mm ，

3、標(biāo)定電子衍射譜333lkh222lkh111lkh111lkh222lkh333lkh1r2r12斑點(diǎn)rr2nhkl16.56.523111216.416.4219133316.816.82200243r311r2r123111133024=82。r3222222212121212121coslkhlkhl lkkhh024133111111000133204花樣指數(shù)標(biāo)定的結(jié)果也可假定斑點(diǎn)1為111u=k1l2-k2l1 v=l1h2-l2h1 w=h1k2-h2k1確定晶帶軸指數(shù) uvwuvw=123指數(shù)（矢量疊加原理，標(biāo)定所有斑點(diǎn)的指數(shù)；測(cè)得r16.5mm，r216.4mm，r316.8mm， 820；，；例： 標(biāo)定al單晶衍射花樣, 15.21mm 1r2r123=82r3ff 111002022113222004133024d2.3382.0251.4321.2211.1691.0120.9290.906024133111111000133204123 假定斑點(diǎn)1為(111)，嘗試斑點(diǎn)