Ultrasonic study on the elastic moduli of the NaTl (B32) structure

The elastic moduli and Debye temperatures of LiAl, LiIn, LiZn, NaIn and NaTl (NaTl type: space group Fd3m) have been determined at room temperature by an ultrasonic pulse transmission technique. The trend between the isotropic bulk modulus (B) and the volume per atom pair ($\text{M}\text{ρ}$) shows that the simple coulombic form of ion-ion interaction is not applicable to the NaTl type structure, while the semiconductor like diamond- or ZnS-, and ionic CsCl-type crystals have contributions from a coulombic attractive force. The bonding character of the NaTl structure is also discussed.