X射线晶体学简介(PPT课件).ppt
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1、X射线晶体学简介中国地质大学(北京)地质实验中心 一、衍射分析方法的发展及基本理论一、衍射分析方法的发展及基本理论二、二、衍射仪基本结构及发展三、粉晶衍射原理、衍射图的特征及应用三、粉晶衍射原理、衍射图的特征及应用四、单晶样品制备四、单晶样品制备五、单晶衍射分析及应用五、单晶衍射分析及应用六、晶体结构测定及晶体学参数六、晶体结构测定及晶体学参数 主要内容主要内容一、衍射分析方法的发展及基本理论一、衍射分析方法的发展及基本理论1、衍射分析的历史及发展2、衍射分析的基本概念及基本理论晶体结构与空间格子衍射的概念、劳埃方程、结构因子、3、倒易点阵及衍射仪设计原理1、衍射分析技术的发展与与X X射线及
2、晶体衍射有关的部分诺贝尔奖获得者名单射线及晶体衍射有关的部分诺贝尔奖获得者名单 2、衍射分析的基本概念及基本理论晶体(1)结构与空间格子-A晶体晶体(crystal)(crystal)It is solid.It is solid.The arrangement of atoms in the crystal is The arrangement of atoms in the crystal is periodic.periodic.格子格子(LatticeLattice)An infinite array of points in space,in which each An infini
3、te array of points in space,in which each point has identical surroundings to all others.point has identical surroundings to all others.晶体结构晶体结构(Crystal StructureCrystal Structure)It can be described by associating each lattice point It can be described by associating each lattice point with a group
4、 of atoms called the with a group of atoms called the MOTIFMOTIF(BASISBASIS)单位晶胞(单位晶胞(Unit CellUnit Cell)The smallest component of the The smallest component of the crystal,which when stacked together with pure crystal,which when stacked together with pure translational repetition reproduces the who
5、le crystaltranslational repetition reproduces the whole crystal晶胞参数晶胞参数Unit Cell DimensionsUnit Cell Dimensions a a,b b and and c c are the unit cell edge lengths.are the unit cell edge lengths.a a,b b and and g g are the angles(are the angles(a a between between b b and and c c,b b between between
6、c c and and a a,g g between between a a and and b cb c.).)(1)晶体结构与空间格子-B等同点与结点格子类型格子的对称点群、劳埃群、衍射群、空间群The 14 possible BRAVAIS LATTICES note that spheres in this picture represent lattice points,not atoms!(1)晶体结构与空间格子-C7 crystal 7 crystal ClassesClassesCrystal systemUnit cell shapeEssential symmetrySp
7、ace latticesCubi a a=b b=c c a a=b b=g=90g=90Four threefold axesP I F Tetragonala a=b bc c a a=b b=g=90g=90One fourfold axisP IOrthorhombic a ab bc c a a=b b=g=90g=90Three twofold axes or mirror planeP I F A(B or C)HexagonaA=bA=bc c a=g=90 a=g=90 b=120b=120One threefold axisPTrigonalA=bA=bc c a=g=90
8、 a=g=90 b=120b=120One threefold axisPa a=b b=c c a a=b b=g g9090One threefold axisRMonoclinica ab bc c a=b=90 a=b=90 g g9090One twofold axis or mirror planeP CTriclinica ab bc c a ab bg g9090noneP金红石的晶体结构金红石的晶体结构金红石的晶体学参数金红石的晶体学参数2、衍射分析的基本概念及基本理论布拉格方程(衍射方向的条件)n=2dsin 衍射方向与晶胞参数的关系:d a a,b b ,c c,a a,
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