Gigantic piezoelectricity in a polycrystalline ceramic actively maintained at a quadruple point.

Transformative technologies demand polycrystalline piezoelectric ceramics with piezoelectric coefficients (d33) exceeding 6000 picocoulomb per Newton (pC/N), but this goal has remained elusive because of the intrinsically weak nature of piezoelectricity and incomplete polarization alignment in polycrystals. We overcome this barrier by placing a polycrystalline lead zirconate titanate (PZT) ceramic in a temperature and electric-field control module so that it operates at a quadruple phase point (QP). This QP ceramic exhibited a d33 of ~6850 pC/N, which surpasses that of commercial PZT ceramics by 10 to 30 times and commercial lead magnesium niobate–lead titanate single crystals by ~4 times. This exceptional property arises from the tricritical nature of the QP, a thermodynamic singularity that produces an ultrasoft lattice and enables complete polarization alignment in polycrystals. The module maintained this performance for surrounding ambient temperature ranging from 25° to 350°C. Editor's summary: Maintaining a critical temperature and applied bias allows a polycrystalline ceramic film to operate with a high piezoelectric coefficient d33. Hao et al. showed that four phases converge for lead titanate, Pb(Zr1-xTix)O3, at x = 0.4 and ~350°C, and that this tricritical point confers colossal electromechanical responses, giant dielectric permittivity, and ultrasoft elasticity. A control module maintained the resulting high d33 of about 6850 picocoulombs per Newton of the film over a wide ambient temperature range. —Phil Szuromi [ABSTRACT FROM AUTHOR]