An electromechanical vice includes a support structure, a component
moveable with respect to the support structure, and a piezoelectric device
mechanically coupled to both the support structure and the component. The
piezoelectric device includes a polycrystalline body and electrodes
located on the body. The body has a composition with a stoichiometry
described by [Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 ].sub.(1-x) [PbTiO.sub.3
].sub.x. The value of x is in the range of about 0.31 to about 0.47.
