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Dense (Pb0.92Ba0.08)Nb2O6‐xmol% MnO2 with 0.25 wt% TiO2 ceramics with a single orthorhombic phase were synthesized through a conventional solid‐state reaction method. Excellent piezoelectric performance (d33 = 90 pC/N) and low dielectric loss (tan δ = 0.5%) are achieved in Mn‐doped samples. Interestingly, the dielectric anomalies are observed in the temperature range of 300–400°C, which could be completely suppressed through Mn doping. The dielectric anomalies are associated with thermally activated domain wall motion, which could be constrained by the defect dipoles produced by Mn doping. More importantly, all samples experience about 12% performance degradation below 300°C, attributed to an accelerated aging process at elevated temperatures. After thermal aging, the samples exhibit excellent performance stability within the temperature range of 25–450°C, showing no further degradation. The results indicate that the PbNb2O6‐based ceramics are promising high‐temperature piezoelectric materials for piezoelectric devices operating at temperatures up to 450°C. [ABSTRACT FROM AUTHOR]

In this work, a functionally graded spherical piezoelectric transducer (FG-sPET) is proposed and an accurate theoretical model is constructed, mainly composed of a three-port electromechanical equivalent circuit model (EECM). The EECM of FG-sPET can be connected to that of other vibration systems according to the boundary conditions (force and vibration velocity), making it easier to evaluate the whole mechanical vibration system. The validity of the EECM for FG-sPET is verified by comparison with other literature. The effects of geometric dimensions and non-uniform coefficients on the vibration characteristics (resonance/anti-resonance frequencies and effective electromechanical coupling coefficient) of FG-sPET are also studied, contributing to systematically evaluating the key factors determining the vibration characteristics of FG-sPET. The proposed analytical system is of excellent guidance for the structural optimization design of functionally graded piezoelectric devices. [ABSTRACT FROM AUTHOR]

High-temperature ultrasonic detection technology has attracted unprecedented attention in recent years. However, the detection capability of piezoelectric ultrasonic transducers at high temperatures is limited by the properties of piezoelectric ceramics. To tackle this, 0.125 mol% Nb5+ doped 0.36BiScO 3 -0.64PbTiO 3 (BSPT-0.125 Nb) ceramics were prepared by the conventional solid-state reaction method. The dielectric, ferroelectric, and piezoelectric properties of BSPT-0.125 Nb as a function of temperature were characterized systematically, and compared to those of commercial Pb(Zr,Ti)O 3 (PZT) ceramics (PZT-4, PZT-5A, and PZT-8). The results indicate that the BSPT-0.125 Nb exhibits better temperature stability than PZT ceramics, showing greater potential for high temperature piezoelectric device application. To exemplify, two high-temperature single-element ultrasonic transducers based on BSPT-0.125 Nb and PZT-5A were fabricated. The impedance and echo response of the transducers were tested on a heating platform at different temperatures. The results show that the transducer based on BSPT-0.125 Nb ceramics had stronger pulse-echo response signal at high temperature, and could maintain a stable electrical resonance and received echo responses until 400 °C, which is attributed to high Curie temperature and large piezoelectric voltage coefficient. The results verify the greater potential of BSPT-0.125 Nb ceramics over PZT system ceramics in high-temperature ultrasonic transducers for ultrasonic detection applications. [Display omitted] • The BSPT-0.125Nb piezoelectric ceramic exhibits better temperature stability than PZT ceramics. • The BSPT-0.125Nb piezoelectric ceramic exhibits high Curie temperature and large piezoelectric voltage coefficient. • Two high-temperature ultrasonic transducers (HUPTs) based on BSPT-0.125Nb and PZT-5A were fabricated. • The HUPT based on BSPT-0.125Nb can maintain a stable electrical resonance and receive echo responses until 400 °C. [ABSTRACT FROM AUTHOR]