Simple crystal structure

Simple crystal structure
1.Sodium chloride structure (NaCl)
NaCl structure is shown in Fig.10
•The lattice is FCC
•The basis is consists of 1Na+ ion and 1Cl- ion separated by ½ the diagonal of a unit cube.
•There are 4 units in each unit cube.
• The coordination number of NaCl is 6
•The coordinates of atoms in unit cube are
0,0,0 ; ½,½,0; ½,0,½; 0, ½,½
½,½,½ ; 0,0, ½ ; 0, ½,0 ; ½,0,0
ClCs structure is shown in Fig.11
•The lattice is BCC
• The basis has 1 Cs+ ion at 0,0,0 and 1 Cl- ion at ½,½,½
• The coordination number of CsCl is 8
A close packed- layer of spheres (atoms) is shown in Fig. 12, with centers at points (A ). A second layer goes in over (B). A third layer (C) may be added in two ways: if it goes in over (A) the order is AB AB AB and the structure is hcp
A close packed- layer of spheres (atoms) is shown in Fig. 12, with centers at points (A ). A second layer goes in over (B). A third layer (C) may be added in two ways: if it goes in over (A) the order is AB AB AB and the structure is hcp