Elastic properties of intermediate valence, Kondo and stable valence RAl₂ compounds

Measurements of ultrasonic velocities and pressure volume behavior show that, compared to integral valence rare earth dialuminides, the intermediate valence compound, YbAl2, is mechanically soft and the Kondo compound, CeAl2, is much less so. These results show that in the case of intermediate valence the degenerate electronic configurations strongly effect the elastic properties while for the Kondo case, where the electronic configurations are nondegenerate, there is little effect. © 1982.