| Material name | Opal | |||||
| Composition | SiO2+nH2O (n = 3 - 10%), L-cristobalite | |||||
| Chemical formula weight | 60.08 | |||||
| System | Tetragonal | |||||
| Temperature (ºC) | 23 | |||||
| a (Å), b (Å), c (Å) | 4.9709(1) | 4.9709(1) | 6.9278(2) | |||
| α (deg), β (deg), γ (deg) | 90 | 90 | 90 | |||
| Unit cell volume (Å3) | 171.2 | |||||
| Calculated density (g/㎝3) | 2.33 | |||||
| Z | 4 | |||||
| Space group | P41212 (No.92) | |||||
| atom | site | g | x/a | y/b | z/c | B (Å2) |
| Si | 4a | 1 | 0.3005(3) | 0.3005(3) | 0 | 1.0 |
| O | 8b | 1 | 0.2392(3) | 0.1037(2) | 0.1786(2) | 1.9 |
| Comment | B values were calculated on the basis of βij values in the reference. | |||||
Reference: J.J. Pluth, J.V. Smith, and J. Faber Jr., Journal of Applied Physics, 57, 1045 (1985).