A linear ultrasonic motor using lead-free piezoelectric ceramics equipped with quadrate plate transducers has been developed. Four lead free piezoelectric plates driving elements formed a multi-driving-end, producing a large thrust and output velocity. The design of the stator enables two operating modes with coincident frequency. A microscopic view suggests that the material particles at the top of four projections move in ellipses and drive the slider alternately via frictional forces to realize linear motion. The fabrication and characterization of the lead-free piezoelectric ceramics achieving the drive of stator were given in the context.

Pb(Mg1/3Ta2/3)O3–Pb(Mn1/3Sb2/3)O3–Pb(ZrxTi1−x)O3 quaternary piezoelectric ceramics with different compositions near the morphotropic phase boundary were synthesized using a conventional solid state reaction method. The phases, microstructures, ferroelectric, piezoelectric and dielectric properties of the system were investigated. A transition from rhombohedral to tetragonal phase was observed as the Zr/Ti ratio decreased. The P–E loops presented pinched shapes at low electric fields and the distortions disappeared at high electric fields. The dielectric study revealed a diffuse phase transition behavior in the ceramics. The optimal dielectric and piezoelectric properties ɛr = 817, d33 = 285 pC/N, kp = 0.55, TC = 302 °C, tan δ = 0.4% and Qm = 1600 of the ceramics were obtained at the composition of Zr/Ti = 50/50. Vibration velocity at ΔT = 20 °C was found as high as 0.74 m/s for this composition, which was almost 2.5 times as that of the commercial hard PZT ceramics.Research highlights▶ Good “soft” and “hard” properties of Pb(Mg1/3Ta2/3)O3–Pb(Mn1/3Sb2/3)O3–Pb(ZrxTi1−x)O3 (PMgT–PMS–PZT) ceramics were obtained at Zr/Ti of 50/50 and vibration velocity of the composition at ΔT = 20 °C is found as high as 0.74 m/s, which is nearly 2.5 times of the commercial hard PZT ceramics. ▶ The P–E loops present pinched shapes at low electric fields and the distortions disappear at high electric fields. ▶ The Pr exhibits a highest value near the MPB, which is quite different from those of bulk PZT single crystals and single-crystal PZT films where Pr proved to have the lowest value both theoretically and experimentally.

Perovskite 0.4Bi(Zn1/2Ti1/2)O3–0.6PbTiO3 (BZT–PT) powders were successfully synthesized from precursor oxides using a high-energy planetary ball milling. The phase development of the powders during milling was studied by means of X-ray diffraction and Raman scattering techniques. The microstructure of the powders was characterized using transmission electron microscopy, and the thermal behavior was studied as well. The results reveal that after 15 h of milling the formation of BZT–PT phase can be completed and submicron agglomerates of small crystallite sized ~ 12 nm are present in the powders. However, further prolonging the milling time to 25 h leads to the amorphization of the BZT–PT phase.

The quaternary piezoelectric ceramics of Pb(Mg1/3Ta2/3)O3–Pb(Mn1/3Sb2/3)O3–Pb(Zr0.52Ti0.48)O3 (PMgT–PMnS–PZT) were synthesized with a conventional method. The phase, microstructure, ferroelectric, dielectric and piezoelectric properties were studied in terms of PMgT content. The results indicate that all ceramics have a pure perovskite phase of tetragonal symmetry while the c/a ratio increases with PMgT content. The PMgT substitution also promotes the densification of the ceramics without significant grain growth when no more than 5 mol.%. The spontaneous polarization Ps increases consistently as revealed by the enhanced tetragonality, whereas the coercive field Ec, which is affected by the internal dipolar field, reaches a minimum at 3 mol.%. When no more than 5 mol.% PMgT is introduced, both the soft and hard properties can be improved simultaneously. However, further introduction of PMgT in place of PMnS induces a rapid decrease in Qm and increase in tan δ  . The 0.05PMgT–0.05PMnS–0.9PZT ceramics have the optimal overall performance: ε33T=683, tanδ = 0.3%, d33 = 227 pC/N, kp = 0.55, Qm = 1830. The ceramics are promising candidates for high power resonant actuator applications.