[011] poled ternary Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) single crystals have been investigated for active materials for acoustic transducers because of their high piezoelectric properties in both shear and transverse modes. In order to use [011] poled PIN-PMN-PT single crystals for acoustic transducers, the characterization of full-matrix material properties is required. In this study, full sets of compliance, dielectric, and piezoelectric constants of [011] poled rhombohedral PIN-PMN-PT were measured by a resonance method. Dimensions and geometries of 12 samples were proposed for measuring 17 independent material constants of [011] poled rhombohedral PIN-PMN-PT single crystals. Two sets of samples with different PT concentrations, 0.24PIN-0.49PMN-0.27PT and 0.24PIN-0.46PMN-0.30PT, were fabricated and their material properties were measured. Measured impedance spectra and simulated impedance spectra of the samples were compared to check the accuracy of the measurements.

The 0.99Bi0.5(Na0.78K0.22)0.5TiO3?0.01LaAlO3, 0.01LaMnO3 or 0.01LaFeO3 (0.99BNKT?0.01LA,0.01LM or 0.01LF) ceramics were prepared by a conventional mixed mothod. The structure andmorphology of the lead free ceramics were characterized by XRD (X-ray diffraction) and FE-SEM (fieldemission scanning electron microscopy). XRD results indicated that the BNKT ceramics modified by LA,LM or LF induced a transition from a ferroelectric tetragonal to a non-polar pseudo-cubic phase, leadingto decrease in the remnant polarization (Pr) and coercive field (Ec) in the P-E hysterisis loops. Theeffects of the BNKT ceramics modified by La-based ABO3 pervskite structure on the electric-fieldinduced strain were investigated, and the largest normalized unipolar strain (Smax/Emax) was found inBNKT-0.01LF ceramic.