  The pressure influence on the lattice vibration of $CaZnF_4$ has been studied
by Raman diffusion up to 17 GPa. Most Raman frequencies increase with
increasing pressure. Three singularities in the pressure induced frequency
evolution are observed around 1.5 GPa, 10 GPa and 17 GPa. The samples
pressurized to 17 GPa or higher do not revert to the ambient pressure phase
after being released, the new phase showing different Raman spectra from the
ordinary one. It is suggested that $CaZnF_4$ undergoes probably sudden lattice
deformations at about 1.5 GPa and 10 GPa, and an irreversible phase
transformation above 17 GPa.
