2.晶体结构与空间点阵-C The 14 possible BRAVAIS LATTICES inote that spheres in this picture represent lattice points, not atoms. g CUBIC ORTHORHOMBIC E ≠b本C HEXAGONAL TRIGONAL单 =b b=c P MONOCLINIC a≠b≠C 4 Types of Unit Cell Primitive c=y=90° 1= body-Centred β*120° F= Face-Centred C= Side-centred TRICLINIC a≠b≠C 7 Crystal Classes 双≠阝*y*90 →14 Bravais lattices
The 14 possible BRAVAIS LATTICES {note that spheres in this picture represent lattice points, not atoms!} 2. 晶体结构与空间点阵-C
7 crystal Classes Crystal Unit cell shape Essential symmetry pace system lattices Cubi a=b-c a=B=r=90 Four threefold axes PIF Tetragona a=b≠c One fourfold axis P I c=B-=90 0 rthorhom a≠b≠c Three twofold axes or PI FA(B bic c=B=y=90 mirror plane or C) Hexagona A=b+c a=r-90 One threefold axis B=120 Trigonal A=b≠ca=y=90 One threefold axis B=120 a=b=c One threefold axis R =B=y≠90 Monocline a≠b≠ca=B=90ne twofold axis or C y≠90 mirror plane Triclinic a≠b≠c none ≠B≠y≠90
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 Tetragona l a=b≠c a=b=g=90 One fourfold axis P I Orthorhom bic 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 Monoclini c 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