| Material name | Ruby | |||||
| Composition | α-Al2O3 (trace Cr ion) | |||||
| Chemical formula weight | 101.96 | |||||
| System | Trigonal | |||||
| Temperature (ºC) | r.t. | |||||
| a (Å), b (Å), c (Å) | 4.759(1) | 4.759(1) | 12.991(5) | |||
| α (deg), β (deg), γ (deg) | 90 | 90 | 120 | |||
| Unit cell volume (Å3) | 254.8 | |||||
| Calculated density (g/㎝3) | 3.99 | |||||
| Z | 6 | |||||
| Space group | R3c (No.167) | |||||
| atom | site | g | x/a | y/b | z/c | B (Å2) |
| Al | 12c | 1 | 0 | 0 | 0.3520(3) | - |
| O | 18e | 1 | 0.306(4) | 0 | 1/4 | - |
Reference: R.E. Newnham and Y.M. de Haan, Zeitschrift für Kristallographie, 117, 235 (1962).