Mn-modified Pb(Mg1/3Nb2/3)O-3-PbTiO3 ceramics: Improved mechanical qualityfactors for high-power transducer applications

Piezoelectric ceramics are potential high-power electroacoustic sources, an d have been studied for many years. However, when these devices are driven under high-level vibration, the electromechanical characteristics depart si gnificantly from the conventional linear piezoelectric relationships due to the loss and nonlinear behavior in terms of elastic and dielectric propert ies. In this paper, we present results concerning the development of modifi ed Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) ceramics with improved mechanical qual ity factors for high-power application. We have focused efforts on base PMN -PT compositions close to the morphotropic phase boundary. Evidence will be presented which indicates that the improved mechanical quality factor resu lts from the introduction of "hard" characteristics into PMN-PT by the subs tituents. Investigations of the nonlinearity of the electromechanical prope rties on the vibrational amplitude were performed using a constant displace ment method. The degradation of the mechanical quality factor with increasi ng drive amplitude also presents thermal stability problems for the usage o f these materials in high-power transducer applications.