PMN-PT based quaternary piezoceramics with enhanced piezoelectricity and temperature stability

The phase structure, piezoelectric, dielectric, and ferroelectric properties of (0.80-x)PMN-0.10PFN-0.10PZ-xPT were investigated systematically. The morphotropic phase boundary (MPB) was confirmed to be 0.30<x<0.34. Both MPB compositions of x=0.32 and x=0.33 exhibit high piezoelectric coefficients d₃₃=640 pC/N and 580 pC/N, electromechanical couplings k_p of 0.53 and 0.52, respectively. Of particular importance is that the composition with x=0.33 was found to process high field-induced piezoelectric strain coefficient d₃₃* of 680pm/V, exhibiting a minimal temperature-dependent behavior, being less than 8% in the temperature range of 25-165°C, which can be further confirmed by d₃₁, with a variation of less than 9%. The temperature-insensitive d₃₃* values can be explained by the counterbalance of the ascending dielectric permittivity and descending polarization with increasing temperature. These features make the PMN-PT based quaternary MPB compositions promising for actuator applications demanding high temperature stability.