Recent development in lead-free perovskite piezoelectric bulk materials

High strain piezoelectric ceramics are the state-of-the-art materials for high precision, positioning devices. A comprehensive review of the latest developments of the various types of perovskite piezoelectric ceramic systems is presented herein, with special attention given to three promising families of lead-free perovskite ferroelectrics: the barium titanate, alkaline niobate and bismuth perovskites. Included in this review are details of phase transition behavior, strain enhancement approaches, material reliabilities as well as the status of some promising applications. This current review describes both compositional and structural engineering approaches that are intended to achieve enhanced strain properties in perovskite piezoelectric ceramics. The factors that affect the strain behavior of high-strain perovskite piezoelectric ceramics are addressed. The reliability characteristics of these high-strain ferroelectrics as well as the recent approaches to the long-term electrical, thermal and time-stability enhancement are summarized. Several promising applications of high-strain perovskite materials are introduced, which take advantages of their characteristics; examples include high-energy storage, pyroelectric and electro-caloric effect and luminescent properties.

Progress in high-strain perovskite piezoelectric ceramics

Sr0.7Bi0.2TiO3 (SBT) was introduced into Bi0.5Na0.5TiO3 (BNT) via a standard solid-state route to modulate its relaxation behaviour and energy storage performance. With increasing SBT content, the perovskite structure of BNT transforms from a rhombohedral phase to a weakly polarized pseudo-cubic phase, and the relaxation behaviour is enhanced. In particular, the EDBS is improved from 120 kV/cm of BNT to 160 kV/cm of 0.6BNT-0.4SBT, which displays a large recoverable energy storage density (Wrec = 2.20 J/cm3), implying a large potential ability of energy storage for the 0.6BNT-0.4SBT ceramic. Moreover, both dielectric properties (28–326 °C) and energy storage properties (20–140 °C) exhibit a good thermal stability for the same 0.6BNT-0.4SBT composition. These characteristics suggest 0.6BNT-0.4SBT ceramic could be a promising candidate to be applied in a pulse power system over a broad temperature range.

Enhanced energy density and thermal stability in relaxor ferroelectric Bi0.5Na0.5TiO3-Sr0.7Bi0.2TiO3 ceramics

Lead-free piezoelectric ceramics, (Bi 1/2 Na 1/2 ) 0.935 Ba 0.065 Ti 1− x (Fe 1/2 Nb 1/2 ) x O 3 , were prepared by the conventional solid-state reaction method. The room temperature ferroelectric P–E loops illustrated the transition of ferroelectric domains. The composition and electric field dependent strain behavior of this system were investigated. A highest unipolar strain of ∼0.422% and corresponding normalized strain, d * 33 ( =  S max / E max ) of 844 pm/V under an applied field of 50 kV/cm were observed at x  = 0.020, due to the destabilization of the ferroelectric order. It is observed that the unipolar strain of BNBT-0.02FN is temperature insensitive, and the d * 33 maintains a high value of ∼600 pm/V at 90 °C. The observed large strain behavior can be attributed to the transformation from the ferroelectric phase at zero electric field into a relaxor ferroelectric phase under an applied electric field. The large strain response with good temperature stability would be quite suitable for environmental-friendly solid-state actuator applications.

Electric field-induced ultrahigh strain and large piezoelectric effect in Bi1/2Na1/2TiO3-based lead-free piezoceramics

Properties of lead-free Bi0.5-xLaxNa0.40K0.10Ti0.98Zr0.02O3 (x = 0.000–0.040) ceramics were investigated. All ceramics have a pure perovskite structure. A high energy storage density (∼1.00 J/cm3) at room temperature (RT) is noted for the x = 0.030 sample, while x = 0.020 and 0.040 samples have very high thermal stability of energy storage density of ∼3% (at 75–150 °C). Furthermore, the x = 0.030 and 0.040 samples have the highest energy storage efficiency (η) value of 94% at 125 °C with high thermal stability (η = 84–95% at 25–150 °C). The x = 0.005 sample has high electric field-induced strain (Smax = 0.42%) and high normalized strain coefficient (d*33 = Smax/Emax = 700 pm/V) with large improvements (∼200% and 163% for Smax and d*33, respectively), as compared to the based composition. This ceramic system has potentials for piezoelectric and/or energy storage density applications.

High thermal stability of energy storage density and large strain improvement of lead-free Bi0.5(Na0.40K0.10)TiO3 piezoelectric ceramics doped with La and Zr

Synthesis and ferroelectric behavior of Gd doped BNT ceramics

Effect of neodymium substitution on structural and ferroelectric properties of BNT ceramics

Lead free piezoelectrics [1-x{(Bi0.96La0.04)0.5Na0.5TiO3}−x(Ba0.90Ca0.10TiO3)] (BLNT-BCT) with compositions x ≤ 0.20 have been synthesized by a semi-wet route and the compositions around the MPB region have been systematically investigated using x-ray diffraction and Raman spectroscopy. X-ray diffraction analysis confirms phase formation without any traces of secondary phases. Rietveld refinement of x-ray diffraction data revealed different structural symmetry for a different range of compositions viz., (i) rhombohedral (R3c) [x ≤ 0.08] (ii) rhombohedral (R3c) + tetragonal (P4mm) (MPB) [0.10 ≤ x ≤ 0.15] (iii) tetragonal (P4mm) [0.15 < x ≤ 0.20], which is confirmed by Raman spectroscopy. The structural phase transitions have been correlated with piezoelectric properties and the composition with x = 0.12 depicts better piezoelectric properties amongst studied compositions, which is attributed to the coexistence of rhombohedral and tetragonal phases.

https://iopscience.iop.org/article/10.1088/0022-3727/48/5/055301/pdf

Vijayeta Pal

Papers

Synthesis and ferroelectric behavior of Gd doped BNT ceramics

Effect of neodymium substitution on structural and ferroelectric properties of BNT ceramics

Investigation of MPB region in lead free BLNT-BCT system through XRD and Raman spectroscopy

Structural investigation of Ca/Zr co-substituted BaTiO3 through XRD and Raman spectroscopy

Preparation, microstructure and relaxor ferroelectric characteristics of BLNT–BCT lead-free piezoceramics