The face-centered cube contains eight vertex atoms at the corners of a cell and six additional atoms in the faces of the cell. A ball-and-stick model graatly exaggerates the distances betwen the atoms.
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| Ball-and Stick Model The face-centered cube contains eight vertex atoms at the corners of a cell and six additional atoms in the faces of the cell. A ball-and-stick model graatly exaggerates the distances betwen the atoms. |
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Spacefilling Model A spacefilling model of the face-centered cube shows the size of the atoms in correct proportion to the cell. |
| Spacefilling Unit Cell
A spacefilling unit cell only shows the portions of the atoms which lie inside the cell. Each of the vertex atoms lie 1/8 inside the cell, and each face atom lies 1/2 inside the cell, giving the equivalent of four atoms inside the cell. It should be apparent from this model that the atoms do not touch along an edge of the cell, but rather along the side diagonal, which connects opposite atoms along a face of the cell. |
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Close-Packed Layers The face-centered cubic lattice is equvalent to the cubic close-packed structure, and can alternately be visualized as ABC-stacked close-packed layers. Here color is used to represent the three layers. If the model were expanded, a red layer would clearly be visible. |
| Octahedral Hole Close-packed structures contain octahedral and tetrahedral holes. This illustration shows one octahededtal hole. An octahedtal hole is formed by three atoms in in one close-packed layer and three atoms in another close-packed later immediately above or below; in this case three atoms from the blue layer and three atoms from the green layer. Note that this octayedral hole is formed by the six face atoms. |
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Tetrahedral Holes Tetrahedral holes are defined by three atoms in one close-packed layer and a atom in the next close-packed latyer immeddiately above and below the first. For example, the lower tetrahedral hole is defined by three atoms in the green close-packed layer and a single atom in the blue close-packed later. The unit cell actually contains a total of eight tetrahedrahal holes. Each of the eight faces of the occtahedral hole shares a face with one tetrahedral hole. |