Practical Electron Microscopy and Database

An Online Book, Second Edition by Dr. Yougui Liao (2006)

Practical Electron Microscopy and Database - An Online Book

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Diffraction Comparison between Different Cubic Crystal Structures

Based on the periodicity of the observed reflections in diffraction patterns or profiles, it is possible to distinguish the crystal structures. For instance, Figure 2507 shows the comparison of XRD (X-ray diffraction) results from different cubic crystal structures. Here, the three integers (h, k, and l) represent the Miller indices.

Comparison of XRD results from materials with different cubic crystal structures

Figure 2507. Comparison of XRD results from different cubic crystal structures.

Table 2507a shows the d-ratios for cubic crystal, where d1 and d2 are d-spacings.

Table 2507a. d-ratio for cubic crystal

d1/d2
100
110
111
200
211
220
311
100
1            
110
1.414 1          
111
1.732 1.225 1        
220
2 1.414 1.155 1      
211
2.45 1.732 1.414 1.225 1    
220
2.828 2 1.633 1.414 1.155 1  
311
3.32 2.345 1.915 1.658 1.354 1.173 1

Table 2507b. Some symmetrical diffraction patterns of cubic crystals.

Zone axis
[100]
[110]
[111]
Symmetry
Square
Rectangular
Hexagonal
Aspect Ratio
1:1 1: for BCC, SC (almost hexagonal for FCC) Equilateral

The lattice spacing of cubic structures may be given by,

        lattice spacing of cubic structures ------------------------------- [2507]

where,
          a -- The lattice constant.