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Crystal system
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Space lattice
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Examples
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Cubic
A=b=c,
α = β = ϒ= 90o
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Simple: Lattice points at the eight corners of the unit cells.
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Body centered: Points at the eight corners and at the body centred.
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Face centered: Points at the eight corners and at the six face centres.
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Pb, Hg, Ag Au, Cu, ZnS, diamond, KCl, CsCl, NaCl, Cu2O, CaF2 and alums. etc.
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Tetragonal
a = b ≠ c,
α =β = ϒ = 90o
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Simple : Points at the eight corners of the unit cell.
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Body centered : Points at the eight corners and at the body centre
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SnO2, TiO2
ZnO2, NiSO4
ZrSiO4.PbW O4, white Sn etc.
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Orthorhombic (Rhombic)
a ≠b ≠ c,
α =β = ϒ = 90o
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Simple: Points at the eight corners of the unit cell.
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End centered: Also called side centered or base centered. Points at the eight corners and at two face centres opposite to each other.
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Body centered : Points at the eight corners and at the body centre
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Face centered: Points at the eight corners and at the six face centres.
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KNO3, K2SO4
PbCO3, BaSO4, rhombic sulphur, MgSO4.7H2O etc.
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Rhombohedral
or Trigonal
a = b = c,
α =β = ϒ ≠ 90o
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Simple : Points at the eight corners of the unit cell
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NaNO3, CaSO4, calcite, quartz, As, Sb, Bi etc.
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Hexagonal
a = b ≠ c,
α =β = 90o
ϒ = 120o
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Simple: Points at the twelve corners of the unit cell out lined by thick line.
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or Points at the twelve corners of the hexagonal prism and at the centres of the two hexagonal faces.
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ZnO, PbS, CdS, HgS, graphite, ice, Mg, Zn, Cd etc.
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Monoclinic
a ≠ b ≠ c,
α = ϒ= 90o
β ≠ 90o
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Simple : Points at the eight corners of the unit cell
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End centered : Point at the eight corners and at two face centres opposite to the each other.
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Na2SO4.10H2O
Na2B4O7.10H2O
CaSO4.2H2O monoclinic sulphur etc.
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Triclinic
a ≠ b ≠ c,
α ≠ β ≠ ϒ= 90o
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Simple : Points at the eight corners of the unit cell.
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CaSO4.5H2O K2Cr2O7, H3BO3
etc.
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