Since the stoichiometry of the salt is 2:1, we must fill all of the tetrahedral holes (the FCC structure gives four selenides, thus we need eight lithiums). will occupy the latice points that define ...

This single layer is the precursor of the body centered cubic (BCC) unit cell. The lattice points are in the same general form as the simple cubic (SC) unit cell, with the exception that the atoms are ...