The 32 Crystal Classes | |||||||||||||
Crystal system |
Number of symmetry elements |
Generating matrices |
Independent components of rank 1 tensors1 |
Independent components of symmetric rank 2 tensors2 |
Independent components of asymmetric rank 2 tensors |
Independent components of asymmetric rank 3 tensors3 |
Independent components of symmetric rank 4 tensors |
Independent components of asymmetric rank 4 tensors |
Group elements | ||||
Triclinic |
1 |
C1 |
1 |
|
1 |
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1 |
S2 = Ci |
2 |
|
2 |
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Monoclinic | 2 |
C2 |
3-5 |
|
2 |
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m |
C1h = Cs |
6-9 |
|
2 |
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2/m |
C2h |
10-15 |
|
4 |
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Orthorhombic |
222 |
V = D2 |
16-24 |
|
4 |
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mm2 |
C2v |
25-46 |
|
4 |
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mmm |
Vh = D2h |
47-74 |
47: YBa2Cu3O7-x |
8 |
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4 |
C4 |
75-80 |
|
4 |
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4 |
S4 |
81-82 |
|
4 |
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4/m |
C4h |
83-88 |
|
8 |
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422 |
D4 |
89-98 |
|
8 |
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4mm |
C4v |
99-110 |
8 |
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42m |
Vd = D2d |
111-122 |
|
8 |
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4/mmm |
D4h |
123-142 |
139: face centered tetragonal, In |
16 |
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3 |
C3 |
143-146 |
|
3 |
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3 |
S6 = C6i |
147-148 |
|
6 |
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32 |
D3 |
149-155 |
154: α-Quartz |
6 |
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3m |
C3v |
156-161 |
161: ferroelectric LiNbO3 |
6 |
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3m |
D3d |
162-167 |
12 |
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6 |
C6 |
168-173 |
6 |
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6 |
C3h = S3 |
174 |
6 |
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6/m |
C6h |
175-176 |
|
12 |
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622 |
D6 |
177-182 |
180: β-Quartz |
12 |
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6mm |
C6v |
183-186 |
12 |
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6m2 |
D3h |
187-190 |
|
12 |
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6/mmm |
D6h |
191-194 |
194: hcp, Mg, Be, Sc, α-Ti, Co, Zn, Y, Zr, Tc, Ru, Cd, Gd, Tb, Dy, Ho, Er, Tm, Lu, Hf, Re, Os, Tl, graphite, MoS2, ice Ih |
24 |
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23 |
T |
195-199 |
12 |
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m3 |
Th |
200-206 |
|
24 |
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432 |
O |
207-214 |
|
24 |
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43m |
Td |
215-220 |
216: Zincblende, ZnS, GaAs, GaP, InAs, SiC |
24 |
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m3m |
Oh |
221-230 |
221: CsCl, cubic perovskite |
48 |
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1 Rank 1 tensors are vectors. Examples of properties described by rank 1 tensors are pyroelectricity and pyromagnetism.
2 Rank 2 tensors are matrices. Examples of properties described by rank 2 tensors are electrical conductivity, thermal conductivity, dielectic constant, magnetic susceptibility, and thermal expansion. Only the upper elements of the matrices are given because gij = gji.
3 Examples of properties described by rank 3 tensors are piezoelectricity and piezomagnetism.