90 4.4 ระบบผลึก (Crystal system) ระบบผลึกทั้งหมดที่เปนไปได และสอดคลองกับ Space lattice ทั้ง 14 แบบ นั้น มีเพียง ระบบผลึก 7 ระบบ ดังตาราง Table 4 - 2 CLASSIFICATION OF THE SPACE LATTICE BY CRYSTRAL SYSTEM Crystal System Cubic Tetragonal Orthorhornbic
Rhombohedral Hexagonal Monoclinic Triclinic
Axial lengths and interaxial angles Three equal axes at right angles: a = b = c , ∝ = β = γ= 900 Three axes at right angles, two equal: a = b ≠ c, ∝ = β = γ = 900 Three unequal axes at right angles: a ≠ b ≠ c, ∝ = β = γ = 900 Three equal axes, Equally inclined : a = b = c , ∝ = β = γ ≠ 900 Two equal axes at 1200, Third axes at right angles, a = b ≠ c, ∝ = β =900,γ = 1200 Three equal axes, One pair not at right angles, a ≠ b ≠ c, ∝ = γ = 900 ≠ β Three unequal axes, unequally inclined and none at right angles : a ≠ b ≠ c, ∝ ≠ β ≠ γ ≠ 900
Space lattice Simple cubic Body – centered cubic Face – centered cubic Simple Tetragonal Body – centered tetragonal Simple Orthorhornbic Body–centered orthorhornbic Base–centered orthorhornbic Face–centered orthorhornbic Simple rhombohedral Simple hexagonal Simple monoclinic Face – centered monoclinic Simple triclinic