Structure of CsCl and related compounds

The cesium chloride structure may be regarded as derived from the two equivalent atoms of the cubic bcp unit cell by changing one to Cs+ and the other to 

In the CsCl structure, the coordination number of either kind of ion is eight, and the interionic distance is [ (3)1/2]a. Two principal kinds of compounds crystallize with the CsCl structure. In one group are the halides of the largest univalent ions, and in the other are intermetallic compounds. Some examples are listed in Table 10.3.3. 

The structures of some intermetallic compounds are formed from the stacking of blocks, each resembling a unit cell of the CsCl type. For example, the unit cell of Cr2Al may be regarded as a stack of three blocks, as shown in Fig. 10.3.3(b). 

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