x射線衍射課件第1章x射線晶體學(xué)基礎(chǔ)-在線瀏覽
2025-03-03 08:19本頁(yè)面
【正文】 and c are the unit cell edge lengths. a, b and g are the angles (a between b and c, b between c and a , g between a and b c .) 晶向和晶面指數(shù) 2. 晶體結(jié)構(gòu)與空間點(diǎn)陣 B ? 等同點(diǎn)與結(jié)點(diǎn) ? 結(jié)構(gòu)基元：原子、分子或其集團(tuán) ? 晶體結(jié)構(gòu)＝空間點(diǎn)陣＋結(jié)構(gòu)基元 The 14 possible BRAVAIS LATTICES {note that spheres in this picture represent lattice points, not atoms!} 2. 晶體結(jié)構(gòu)與空間點(diǎn)陣 C 7 crystal Classes Crystal system Unit cell shape Essential symmetry Space lattices Cubi a=b=c a=b=g=90 Four threefold axes P I F Tetragonal a=b≠ c a=b=g=90 One fourfold axis P I Orthorhombic a≠ b≠ c a=b=g=90 Three twofold axes or mirror plane P I F A(B or C) Hexagona A=b≠ c a=g=90 b=120 One threefold axis P Trigonal A=b≠ c a=g=90 b=120 One threefold axis P a=b=c a=b=g≠ 90 One threefold axis R Monoclinic a≠ b≠ c a=b=90 g≠ 90 One twofold axis or mirror plane P C Triclinic a≠ b≠ c a≠ b≠ g≠ 90 none P 2. 晶體結(jié)構(gòu)與空間點(diǎn)陣 D 點(diǎn)陣類型 ◆ 陣點(diǎn)的坐標(biāo)表示 ●以任意頂點(diǎn)為 坐標(biāo)原點(diǎn) ，以與原點(diǎn)相交的三個(gè)棱邊為 坐標(biāo)軸 ，分別用點(diǎn)陣周期（ a、 b、c）為 度量單
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