GAMGI Tutorials: CsCl crystalline structure

# CsCl crystalline structure

- Page 1

The CsCl structure is observed in metallic compounds such as CuZn (beta-brass), AlNi, AgMg and CuPd, but also in ionic crystals with equal number of cations and anions, when the cation is slightly smaller than the anion: CsCl, Nh4Cl, TlBr, etc.

To build this structure, first we create the cell with the observed lattice parameters, then the Cs, Cl atoms used as models, with the observed ionic radius, and then link the cell with the atoms.

1. Press Cell->Create and set System to c, Lattice to P (Primitive Cubic) and a to 4.018 (so ions will be in contact along <111> directions). Press Ok to create the cell.
2. Select Atom->Create and set Style to Solid, Size to 1.0 and Variancy to 1.0. Set Element to Cs, Radius to 1.670 (ionic radius for Cs+) and press the mouse over the graphic area. A Cs atom is created where the mouse was pressed.
3. Set Element to Cl, Radius to 1.810 (ionic radius for Cl-) and press the mouse over the graphic area. A Cl atom is created where the mouse was pressed.
4. Press Cell->Link and select the Crystal link method. Press the mouse over the cell, and then over the Cs atom, to identify the objects to link. Set the x, y, z coordinates (Position page) to 0.5, 0.5, 0.5 and press Ok. 1 atom of Cs is now visible, in the center, inside the cell.
5. Repeat the link procedure above, but this time pressing the mouse over the Cl atom, and setting the x, y, z coordinates to 0.0, 0.0, 0.0. 8 atoms of Cl are now visible, in the vertices, corresponding to a total of 1 atom inside the cell.
6. Select Light->Create and press Ok, to add a light and give atoms a three dimensional look.
7. Remove the Cs,Cl atoms used as models during the building process, pressing Atom->Remove and clicking the mouse over the two atoms.
8. Rotate,move,scale the CsCl cell with the mouse. Press Atom->Measure to determine lengths and angles between atoms.

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