The Pearson symbol or Pearson symbol is a set of symbols used in crystallography as a means of describing the crystal structure created by WB Pearson . A symbol often consists of two letters and a number, for example:
- Diamond Structure - CF 8
- Rutile structure - tP 6
The first two letters indicate the Bravais lattice , with the first lowercase letter indicating the crystal class (or syngony ), and the second capital letter the lattice type. The number indicates the number of atoms in the unit cell. IUPAC recommends that the number be used to indicate the structure of inorganic solids in italics , where it is possible to write this number with an error due to ambiguity.
| a | triclinic |
| m | monoclinic |
| o | orthorhombic |
| t | tetragonal |
| h | hexagonal and rhombohedral |
| c | cubic |
| C | Basocentric |
| F | Face centered |
| I | Volume centered |
| R | Rhombohedral |
| P | Primitive |
| Class | English title | Lattice | Pearson Symbol Prefix |
|---|---|---|---|
| Triclinic | a northic | P | aP |
| Monoclinic | m onoclinic | P | mP |
| C | mC | ||
| Orthorhombic | o rthorhombic | P | oP |
| A, B, C | oS [1] | ||
| F | oF | ||
| I | oI | ||
| Tetragonal | t etragonal | P | tP |
| I | tI | ||
| Hexagonal (and trigonal P) | h exagonal (and trigonal P) | P | hP |
| Rhombohedral | Rhombohedral | R | hR |
| Cubic | c ubic | P | cP |
| F | cF | ||
| I | cI |
Pearson Symbol and Space Group
The Pearson symbol ambiguously determines the structure of the crystal and even its spatial group . For example, three different crystal structures - NaCl (space group Fm 3 m ), diamond ( Fd 3 m ) and sphalerite ( F 4 3m ) - have different space groups, but the same Pearson symbol is cF8.
See also
- List of Structural Types
- Crystal structure
- Lattice Brave
- Crystal cell
Notes
- ↑ http://old.iupac.org/publications/books/rbook/Red_Book_2005.pdf Currently, the letter S is used to denote all base-centered lattices (A, B, C)