Electromechanical Properties of Acceptor‐Doped Lead‐Free Piezoelectric Ceramics

Abstract

We have studied the processing and electromechanical properties of Mn and Fe‐doped 0.88[Bi0.5Na0.5TiO3]–0.08[Bi0.5K0.5TiO3]–0.04[Bi0.5Li0.5TiO3] piezoelectric ceramics prepared by the mixed oxide route. Different amounts of Mn (0.01, 0.014, 0.015, 0.016, 0.017, 0.02, 0.022) or Fe (0.0125, 0.015, 0.0175) were doped to this lead‐free piezoelectric composition. Ceramics were sintered at different temperatures (1075°C–1150°C) to achieve the highest density and mechanical quality factor. Mn or Fe doping resulted in a considerable enhancement of Qm in both planar and thickness resonance modes. In 1.5 mol% Mn‐doped ceramics sintered at 1100°C, a planar Qm of about 970 and tanδ of 0.88% were obtained. In Fe‐doped ceramics, a planar Qm as high as 900 was achieved. Acceptor dopants also resulted in decreasing the coupling coefficients, the piezoelectric charge coefficient, and the dielectric constant.

High Power Performance of Manganese‐Doped BNT‐Based Pb‐Free Piezoelectric Ceramics

“…Table shows the density and electromechanical properties of undoped and Mn‐doped ceramics sintered at 1100°C extracted from our recent publication . Increasing the Mn concentration up to 1.5 mol%, remarkably enhanced the planar Q m .…”

“…Piezoelectric planar and thickness coupling coefficients ( k p and k t , respectively) were calculated from the resonance and antiresonance frequencies of the impedance traces, based on the IEEE standards, as explained in Ref. The experimental setup and details of high power measurements can be found in Refs. Disk‐shaped transducers with thickness of 1 mm and diameter of about 12 mm were used for low power as well as high power measurements.…”

Aging in the relaxor and ferroelectric state of Fe-doped (1-x)(Bi1/2Na1/2)TiO3-xBaTiO3 piezoelectric ceramics

“…leads to increased Q m as well. 29 While some dopants improve the properties of BNT-100xBT, the effects of acceptor-doping in lead-free piezoelectric ceramics and their correlation to aging are not well-understood and systematic studies are missing. Therefore, it appears timely to evaluate the suitability of aging mechanisms known in PZT when applied to the lead-free system BNT-100xBT, and expand understanding on the possible role of the relaxor character of the material.…”

Analysis of Lead-Free Piezoceramic-Based Power Ultrasonic Transducers for Wire Bonding

“…While this piezoceramic displayed properties associated with 'soft' PZT piezoceramics, it was later reported that altering its manufacturing technique [13] and acceptor doping gave KNN piezoceramics the potential to exhibit piezoelectric properties and a mechanical quality factor, Q m , which are comparable with hard piezoceramics [14]. Additionally, it has also been reported that BNT piezoceramics have also exhibited Q m , coupling coefficients k t and k p , and dissipation factor, tan δ, which are comparable to hard PZT after acceptor doping with manganese [15,16]. However, lead-free piezoceramics developed for power applications have also demonstrated low sensitivity and typically exhibit a d 33 that is significantly lower than normally observed in hard PZT piezoceramics [14,16].…”