High electric field-induced strain properties in La-doped Pb(In1/2Nb1/2)O3–PbZrO3–PbTiO3 relaxor ferroelectric ceramics

Piezoelectric ceramics with high strain response and low hysteresis are highly in demand for high-performance actuator applications. Unfortunately, the trade-off relationship between large field-induced strain and low hysteresis in piezoelectric ceramics is a key challenge for designing high-performance piezoelectric actuators. Herein, ymol%La-doped 0.10 Pb(In_1/2Nb_1/2)O₃-xPbZrO₃-(0.90–x)PbTiO₃ [0.10PIN-xPZ-(0.90-x)PT: ymol%La] ternary relaxor ferroelectric ceramics were prepared by conventional solid-state reaction technique. Pb(In_1/2Nb_1/2)O₃ (PIN) as a relaxor end member was introduced into (Pb,La) (Zr,Ti)O₃ (PLZT) system to improve relaxor characteristics and strain properties. A giant strain of 0.23% was obtained in 0.10PIN-0.59PZ-0.31 PT: 8mol%La ceramic at the electric field of 20 kV/cm, with a high piezoelectric d₃₃* of 1150 pm/V and low hysteresis H_y of 6.4%, exhibiting a potential application in high-performance piezoelectric actuators. Furthermore, the effects of La ion doping and components on the ferroelectric, dielectric and electric field-induced strain properties were investigated, and provides a new way for improve the strain properties of piezoelectric materials.     

Small Reduction of the Piezoelectric d33 Response in Potassium Sodium Niobate Thick Films

We have investigated the electromechanical response of potassium sodium niobate (K_0.5Na_0.5NbO₃ or KNN) thick films. The high‐field strain hysteresis loops and weak‐field converse piezoelectric d₃₃ coefficient of the films were measured and compared with those of KNN bulk ceramics under the same electric field conditions. The converse d₃₃ values of the thick films and bulk ceramics were equal to 82.5 and 138 pm/V, respectively, at 0.4 kV/mm. The fundamental difference between the piezoelectric response of the KNN films and the ceramics was studied in terms of the effective (“clamped”) piezoelectric d₃₃ coefficient. The reduction in the piezoelectric d₃₃ coefficient of the KNN films, resulting from the clamping by the substrate, was compared to lead‐based ferroelectric thick films, including Pb(Zr,Ti)O₃ (PZT) and (1 ? x)Pb(Mg_1/3Nb_2/3)O₃?xPbTiO₃ (PMN‐PT). We propose a possible explanation, based on the particular elastic properties of KNN, for the small relative difference observed between the “clamped” and “unclamped” (“bulk”) d₃₃ of KNN, in comparison with lead‐based systems.     

Enhanced piezoelectric properties and temperature-insensitive strain behavior of <001>-textured KNN-based ceramics

In this study, <001>-textured 0.99(K_0.5Na_0.5)_0.95Li_0.05Nb_0.93Sb_0.07O₃−0.01CaZrO₃ [abbreviated as 0.99KNLNS-0.01CZ] lead-free ceramics were prepared by templated grain growth (TGG) using plate-like NaNbO₃ templates and sintered by a two-step sintering process with different soaking time. All textured samples with high Lotgering factor (f >85%) presented orthorhombic and tetragonal coexisting phase, and the proportion of orthorhombic phase was varied with prolonged soaking time. A large piezoelectric constant d₃₃ (~ 310 pC/N) was obtained in the textured samples with a 12 h soaking time, which was almost twice larger compared to the randomly oriented one. Furthermore, the field-induced piezoelectric strain coefficient d₃₃^*(~ 440 pm/V) of the textured ceramics with 6 h soaking time was larger than the value of randomly oriented one (~ 298 pm/V) at room-temperature. Enhanced piezoelectric response and good temperature stability prove that <001>-textured 0.99KNLNS-0.01CZ ceramics are promising candidates in the field of lead-free piezoelectric materials.     

Piezoelectric Property and Strain Behavior of Pb(Yb0.5Nb0.5)O3–PbHfO3–PbTiO3 Polycrystalline Ceramics

(1?x)Pb(Hf_1?yTi_y)O₃–xPb(Yb_0.5Nb_0.5)O₃ (x = 0.10–0.44, y = 0.55–0.80) ceramics were fabricated. The morphotropic phase boundary (MPB) of the ternary system was determined by X‐ray powder diffraction. The optimum dielectric and piezoelectric properties were achieved in 0.8Pb(Hf_0.4Ti_0.6)O₃–0.2Pb(Yb_0.5Nb_0.5)O₃ ceramics with MPB composition, where the dielectric permittivity ε_r, piezoelectric coefficient d₃₃, planar electromechanical coupling k_p, and Curie temperature T_c were found to be on the order of 1930,480 pC/N, 62%, and 360°C, respectively. The unipolar strain behavior was evaluated as a function of applied electric field up to 50 kV/cm to investigate the strain nonlinearity and domain wall motion under large drive field, where the high field piezoelectric d₃₃* was found to be 620 pm/V for 0.82Pb(Hf_0.4Ti_0.6)O₃–0.18Pb(Yb_0.5Nb_0.5)O₃. In addition, Rayleigh analysis was carried out to study the extrinsic contribution, where the value was found to be in the range 2%–18%.     

Giant piezoelectric coefficient of PNN-PZT-based relaxor piezoelectric ceramics by constructing an R-T MPB

xTa-PNN-PZT piezoelectric ceramics with [0.55 Pb(Ni_1/3Nb_2/3)O₃ - 0.45 Pb(Zr_0.3Ti_0.7)O₃ - xwt%Ta₂O₅] + 1 wt% PbO composition (0 ≤ x ≤ 0.7) were prepared by conventional solid-state reaction method. Special attention was paid to the effect of Ta₂O₅ concentration on structural, dielectric, piezoelectric, and ferroelectric properties of these ceramics. In particular, rhombohedral-tetragonal morphotropic phase boundary was observed in PNN-PZT crystal structure near the composition of x = 0.5. At this point, volume fraction of rhombohedral phase was almost equal to that of tetragonal phase. In addition, the ceramic exhibited the optimum values of piezoelectric coefficient, bipolar strain, unipolar strain, and inverse piezoelectric coefficient, i.e., 1090 pC/N, 0.135%, 0.165%, and 1493 pm/V, respectively. Moreover, according to in-situ X-ray diffraction, piezoelectric force microscopy, and in-situ strain measurement results, phase structure of 0.5Ta-PNN-PZT revealed relatively stable piezoelectric behavior at 60 °C.     

Large-strain 0.7Pb(ZrxTi1−x)O3–0.1Pb(Zn1/3Nb2/3)O3–0.2Pb(Ni1/3Nb2/3)O3 piezoelectric ceramics for high-temperature application

0.7Pb(Zr_xTi_1−x)O₃–0.1Pb(Zn_1/3Nb_2/3)O₃–0.2Pb(Ni_1/3Nb_2/3)O₃ (0.7PZT–0.1PZN–0.2PNN, x = 0.44–0.47) piezoelectric powders and ceramics have been prepared through conventional solid-state reaction method. Outstanding piezoelectric and dielectric properties occurred at the morphotropic phase boundary (MPB), which was characterized by the X-ray diffraction spectrum. The MPB composition (x = 0.46) performed high d₃₃ value (641 pC/N), indicating that the system suited large-strain application. The field-induced strain reached 0.25% under a considerably low electric field (0.8 kV/mm) according to the bipolar strain *S–E loops. The effect of the grain size on the aging phenomenon and temperature stability has also been investigated. Due to higher Curie temperature and smaller grain size, the 0.7PZT–0.1PZN–0.2PNN ceramics maintained a high d₃₃ level after depoling treatment, revealing a superior strain capacity for high-temperature application.     

Determining the effects of BaTiO3 template alignment on template grain growth of Pb(Mg1/3Nb2/3)O3 –PbTiO3 and effects on piezoelectric properties

Crystallographic texturing of ferroelectric ceramics is an established method of inducing single crystal-like properties in a ceramic material via epitaxial grain growth according to the template used, otherwise known as Templated Grain Growth (TGG). The piezoelectric enhancement is dependent on the degree of TGG throughout the ceramic, which is closely linked to the tape casting parameters and sintering conditions. Pb(Mg1/3Nb2/3)O₃-PbTiO₃ (PMN-PT) perovskite ferroelectrics with morphotropic phase boundary compositions using 3 vol% BaTiO₃ templates were used for analysis. The blade gap and template size have the greatest impact on the overall grain alignment. The varying degrees of template alignment is related to the different enhancements of TGG and the correlating piezoelectric d₃₃ and d*₃₃. The highest piezoelectric property was demonstrated in PMN-31PT with Lotgering factor of 93% where d₃₃ = 1020 pC/N and d*₃₃ = 1420 pm/V were achieved.     

Excellent piezoelectric properties of PNN-PHT ceramics sintered at low temperature with CuO addition

Multilayer components with excellent piezoelectric performance have been developed for fulfilling the requirement of new-generation electromechanical devices and systems. Multilayering of the piezoelectric ceramic requires good sinterability preferentially at lower temperature. In this study, copper (II) oxide (CuO) was utilized as the sintering additive to increase the sinterability of 0.49Pb(Ni_1/3Nb_2/3)O₃–0.51Pb(Hf_0.3Ti_0.7)O₃ (PNN-PHT) ceramics at low temperature, and simultaneously enhance the piezoelectric and dielectric properties of the ceramics. The results demonstrated that the addition of CuO influenced the sintering behavior, grain growth, and piezoelectric properties of the PNN-PHT ceramics. A ternary high performance piezoelectric PNN-PHT ceramic sintered at 1050°C with 0.5 mol% CuO exhibited excellent properties as follows: d₃₃ = 912 pC N⁻¹ and ε_r = 6665.     

Sintering Behavior,Properties, and Applications of Co‐Fired Piezoelectric/Low Temperature Co‐Fired Ceramic (PZT‐SKN/LTCC) Multilayer Ceramics

Materials and processing conditions have been developed allowing co‐firing of fluxed PZT‐SKN materials with commercial low temperature co‐fired ceramic (LTCC) tapes. Previously, Pb(Zr_0.53, Ti_0.47)O₃–Sr(K_0.25, Nb_0.75)O₃ (PZT‐SKN) ceramics fluxed with 1 wt% LiBiO₂ and 1 wt% CuO addition were shown to sinter to high density at 900°C for 1 h, with a large d₃₃ piezoelectric coefficient of ~415 pm/V. Currently, the master sintering curve (MSC) approach has been used to study the densification behaviors of fluxed PZT‐SKN and LTCC tapes. Different sintering mechanisms for fluxed PZT‐SKN ceramics and LTCC materials are confirmed by analyzing the apparent activation energy (Q_a). Using knowledge gained from MSC results, an optimized sintering profile was developed. Multilayer PZT‐SKN/HL2000 (HeraLock^? Tape, Heraeus) stacks co‐fired at 900°C for 0.5 h maintain large piezoelectric coefficient (high field d₃₃ > 340 pm/V). EDS analysis reveal limited interdiffusion of Pb from PZT‐SKN layers in LTCC and the appearance of Al, Ca, and Si in the PZT‐SKN near the PZT‐SKN/LTCC interface. Further, elemental interdiffusion was not detected at the center of piezoelectric layer in PZT‐SKN/LTCC multilayer ceramics and no subsequent reduction in piezoelectric coefficient d₃₃ was observed. Finally, a piezoelectric microbalance with mass sensitivity of 150 kHz/mg was fabricated using the materials and methods developed.     

High rhombohedral to tetragonal phase transition temperature and electromechanical response in Pb(Yb1/2Nb1/2)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 ferroelectric system near the morphotropic phase boundary

Relaxor-PT crystals, that is, Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) and Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT), have been used in mechanical to electric energy translation devices, such as for high-frequency imaging and underwater detection. However, low temperature usage remains a problem for high temperature applications, which are restricted by rhombohedral to tetragonal phase temperatures (T _R-T). In this work, we synthesized a new xPb(Yb_1/2Nb_1/2)O₃-yPb(Sc_1/2Nb_1/2)O₃-0.37PbTiO₃ (x = 0.2?0.45) (xPYN-yPSN-0.37 P T) ternary piezoelectric polycrystalline with high T _R-T = 225?245 °C. For 0.45PYN-0.18PSN-0.37 P T ceramics, the piezoelectric coefficient d₃₃, mechanical coupling factors k₃₃, k_p, and k_t, and dielectric coefficients ε_r and T _R-T are on the order of 330 pm/V, 68.3%, 54.3%, 49.3%, 930, and 245 °C, respectively. Thermal piezoelectric and ferroelectric behaviors were investigated in 0.45PYN-0.18PSN-0.37 P T polycrystalline, which are good candidates for high temperature piezoelectric application. DSC curves for xPYN-yPSN-0.37 P T systems present two peaks at 1213 and 1291 °C during the cooling process, showing good crystallization behavior and suitability for single crystal growth.     

PNN‐PZN‐PMN‐PZ‐PT Multilayer Piezoelectric Ceramic with Low Sintering Temperature

Multilayer piezoelectric ceramic material with a composition of 0.1Pb(Ni_1/3Nb_2/3)O₃‐0.35Pb(Zn_1/3Nb_2/3)O₃‐0.15Pb(Mg_1/3Nb_2/3)O₃‐0.1PbZrO₃‐0.3PbTiO₃‐4 mol% excess NiO (0.1PNN‐0.35PZN‐0.15PMN‐0.10PZ‐0.3PT‐0.04NiO) was fabricated by a roll‐to‐roll tape casting process and co‐fired with Ag/Pd electrode at low temperature of 950°C. Their dielectric, piezoelectric, and ferroelectric properties were evaluated. The effective piezoelectric coefficient d₃₃ of the obtained multilayer piezoelectric material was 412 pm/V, while d₃₃ for the ceramic pellet was 503 pm/V. Piezoelectric displacement measurements revealed small displacement hysteresis for the multilayer material. The combined characteristics of the multilayer piezoelectric material using the selected composition showed the potential for high power, high strain, and high force actuation applications. In addition, as the composition had a tetragonal phase, which substantially deviated from morphotropic phase boundary (MPB), the excellent properties may be more tolerant to stoichiometric fluctuation, which can allow larger processing and composition window as desired for scalable production.     

Effects of Li2CO3 and Sm2O3 additives on low-temperature sintering and piezoelectric properties of PZN-PZT ceramics

To assist the development of applications for multilayer piezoelectric devices, the low-temperature sintering piezoelectric ceramics of 0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb(Zr_0.49Ti_0.51)O₃ with Li₂CO₃ and Sm₂O₃ additives were fabricated by a conventional solid-state reaction, and their structural and piezoelectric properties were studied. With the addition of Li₂CO₃, the minimum sintering temperature of 0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb(Zr_0.49Ti_0.51)O₃ piezoelectric ceramics was reduced from 1125 °C to 950 °C through the formation of a liquid phase and its piezoelectric properties showed almost no degradation. When the sintering temperature was below 950 °C, however, the piezoelectric properties degraded obviously. The additional Sm₂O₃ resulted in a significant improvement in the piezoelectric properties of 0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb(Zr_0.49Ti_0.51)O₃ ceramic with added Li₂CO₃. When sintered at 900 °C, the optimized properties of the 0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb(Zr_0.49Ti_0.51)O₃ piezoelectric ceramic with 0.3 wt% Li₂CO₃ and 0.3 wt% Sm₂O₃ were obtained as d₃₃ = 483 pC/N, k₃₁ = 0.376, Q_m = 73, ɛ_r = 2524, tan δ = 0.0178.     

Phase transition and electrical properties of Bi0.5(Na0.8K0.2)0.5ZrO3 modified (K0.52Na0.48)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

In this work, (1−x)(K_0.52Na_0.48)Nb_0.95Sb_0.05O₃−xBi_0.5(Na_0.8K_0.2)_0.5ZrO₃ [abbreviated as (1−x)KNNS−xBNKZ, x=0–0.06] lead-free ceramics were fabricated using solid-state reaction method. The effects of BNKZ contents on the phase structure, piezoelectric and ferroelectric properties were investigated. The phase boundaries including orthorhombic-tetragonal (O-T) and rhombohedral-tetragonal (R-T) multiphase coexistence were identified by XRD patterns and temperature-dependent dielectric constant by adding different content of BNKZ. A giant field induced strain (~0.25%) along with converse piezoelectric coefficient d₃₃^* (~629.4 pm/V) and enhanced ferroelectricity P_r (~38 μC/cm²) were obtained when x=0.02, while the specimen with x=0.03 presented the optimal piezoelectric coefficient d₃₃ of 215 pC/N, due to the O-T or R-T phase coexistence near room temperature respectively. These results show that the introduction of Bi_0.5(Na_0.8K_0.2)_0.5ZrO₃ is a very effective way to improve the electrical properties of (K_0.52Na_0.48)(Nb_0.95Sb_0.05)O₃ lead-free piezoelectric ceramics.     

Structure and enhanced properties of perovskite ferroelectric PNN–PZN–PMN–PZ–PT ceramics by Ni and Mg doping

Perovskite ferroelectric oxide ceramics of 0.1Pb(Ni_1/3Nb_2/3)O₃–0.35Pb(Zn_1/3Nb_2/3)O₃–0.15Pb(Mg_1/3Nb_2/3)O₃–0.1PbZrO₃–0.3PbTiO₃ (0.10PNN–0.35PZN–0.15PMN–0.10PZ–0.30PT) with excess MgO and NiO were investigated in this work. The effects of the excess MgO and NiO doping on the ceramic structure, density, dielectric, ferroelectric and piezoelectric properties were studied. The chemical states of nickel were examined using X-ray photoelectron spectroscopy (XPS). Both XPS experimental results and theoretical analyses on the basis of ionic packing indicated that the excess valence-two ions substituted the A-sites in the ABO₃ perovskite structure. By completely eliminating the pyrochlore phase and enhancing densification with the excess NiO and MgO, improved piezoelectric coefficient d₃₃ up to 459 pC/N, higher ferroelectric remnant polarization and dielectric constant were demonstrated when sintered at temperature as low as 850–950 °C.     

Piezoelectric properties of highly densified 0.01Pb (Mg1/2W1/2)O3–0.41Pb (Ni1/3Nb2/3)O3–0.35PbTiO3–0.23PbZrO3+0.1 wt% Y2O3+1.5 wt% ZnO thick films on alumina substrate

This paper reports on the formation of highly densified piezoelectric thick films of 0.01Pb(Mg_1/2W_1/2)O₃–0.41Pb(Ni_1/3Nb_2/3)O₃–0.35PbTiO₃–0.23PbZrO₃+0.1 wt% Y₂O₃+1.5 wt% ZnO (PMW–PNN–PT–PZ+YZ) on alumina substrate by the screen-printing method. To increase the packing density of powder in screen-printing paste, attrition milled nano-scale powder was mixed with ball milled micro-scale powder, while the particle size distribution was properly controlled. Furthermore, the cold isostatic pressing process was used to improve the green density of the piezoelectric thick films. As a result of these processes, the PMW–PNN–PT–PZ+YZ thick film, sintered at 890 °C for 2 h, showed enhanced piezoelectric properties such as P_r=42 μC/cm², E_c=25 kV/cm, and d₃₃=100 pC/N, in comparison with other reports. Such prominent piezoelectric properties of PMW–PNN–PT–PZ+YZ thick films using bi-modal particle distribution and the CIP process can be applied to functional thick films in MEMS applications such as micro actuators and sensors.     

Investigation of morphotropic phase boundaries in PIN–PSN–PT relaxor ferroelectric ternary systems with high Tr-t and Tc phase transition temperatures

New morphotropic phase boundary (MPB) compositions with relatively high T_cs were projected in Pb(In_1/2Nb_1/2)O₃–Pb(Sc_1/2Nb_1/2)O₃–PbTiO₃ (PIN–PSN–PT) solid solution based on the perovskite tolerance factor, and were experimentally confirmed. The phase structure, dielectric, pyroelectric, piezoelectric and ferroelectric properties of PIN–PSN–PT ceramics were investigated. The rhombohedral–tetragonal phase transition temperatures T_r-t on the order of 189–210 °C, Curie temperatures T_c on the order of 274–285 °C and piezoelectric coefficients d₃₃ in the range of 310–360 pC/N, were achieved in xPIN– (1 − x)PSN–0.37PT (x = 0.15–0.23) ceramics, demonstrating a promising relaxor–PbTiO₃ system with high phase transition temperatures. In addition, the maps of T_c, T_r-t, d₃₃ and ε_r with respect to composition were established, based on which, a clear direction for composition screening in future crystal growth of the PIN–PSN–PT system was given.     

Crystal structure and piezoelectric properties of xPb(Mn1/3Nb2/3)O3–(0.2 − x)Pb(Zn1/3Nb2/3)O3–0.8Pb(Zr0.52Ti0.48)O3 ceramics

Pb(Mn_1/3Nb_2/3)O₃–Pb(Zn_1/3Nb_2/3)O₃–Pb(Zr_0.52Ti_0.48)O₃ (designated as PMnN–PZN–PZT) piezoelectric ceramics were prepared and the effects of PMnN content on the crystal structure and electrical properties were investigated. The results show that the pure perovskite phase forms in these ceramics. The crystal structure changes from tetragonal to rhombohedral and the lattice constant decreases with increase of PMnN content. The morphotropic phase boundary (MPB) of xPMnN–(0.2 ? x)PZN–0.8PZT ceramics occurs where the content of PMnN, x, lies between 0.05 and 0.085 mol. The dielectric constant (?), piezoelectric constant (d₃₃) and Curie temperature (T_c) decrease, while the mechanical quality factor (Q_m) increases with the increase of PMnN content. The ceramic with composition 0.075PMnN–0.125PZN–0.8PZT has the optimal piezoelectric properties, ? is 842, d₃₃ is 215 pC/N, T_c is 320 °C, k_p is 0.57 and Q_m amounts to 1020, which makes it a promising material for high power piezoelectric devices.     

Growth and electrical properties of high-Curie point rhombohedral Mn-Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 thin films

High-quality ternary relaxor ferroelectric (100)-oriented Mn-doped 0.36Pb(In_1/2Nb_1/2)O₃-0.36Pb(Mg_1/3Nb_2/3)O₃-0.28PbTiO₃ (Mn-PIMNT) thin films were grown on SrRuO₃-buffered SrTiO₃ single-crystal substrate in a wide deposition temperature range of 550-620°C using the pulsed laser deposition method. The phase structure, ferroelectric, dielectric, piezoelectric properties, and nanoscale domain evolution were studied. Under the deposition temperature of 620°C, the ferroelectric hysteresis loops and current-voltage curves showed that the film owned significantly enhanced remnant ferroelectric polarization of 34.5 μC/cm² and low leakage current density of 2.7 × 10⁻¹⁰ A/cm². Moreover fingerprint-type nanosized domain patterns with polydomain structures and well-defined macroscopic piezoelectric properties with a high normalized strain constant of 40 pm/V was obtained. Under in situ DC electric field, the domain evolution was investigated and 180° domain reversal was observed through piezoelectric force microscope. These global electrical properties make the current Mn-PIMNT thin films very promising in piezoelectric MEMS applications.     

The effect of B site doping of Nb5+ and aging process on the properties of BNKT-BT lead-free piezoelectric ceramics

This research explored the influence of Nb⁵⁺ doping on the electrical properties and microstructure of [0.852(Bi_0.5Na_0.5)-0.11(Bi_0.5K_0.5)-0.038Ba]Ti_(1-x)Nb_xO₃ (designated as BNKT-BT). The BNKT-BT samples were fabricated and the XRD results showed that the doping of Nb⁵⁺ ions induced a transformation from the coexistence of both rhombohedral and tetragonal phase to a single pseudo cubic phase. Also, the doping of Nb⁵⁺ ions caused the temperature of ferroelectric state-ergodic relaxor state transition to decrease below the room temperature (RT). The SEM observations showed that the Nb⁵⁺ doping had a minor effect on the grain size of BNKT-BT samples. In addition, the samples achieved a large electrostrain of 0.43% (d*₃₃ = S_max/E_max = 614 pm/V) under 7 kV/mm at RT. Moreover, the aging process employed at 80 °C for two weeks in air could effectively increase the electrostrain from 0.38% to 0.41% under 6 kV/mm (d*₃₃ = 683 pm/V) and reduce the strain hysteresis from 57% to 34%. These results indicated that the B site doping, combined with the aging process, could provide an effective way to enhance the electrostrain performance of lead-free piezoelectric ceramics.     

Enhanced piezoelectric properties of Sm3+-modified PMN-PT ceramics and their application in energy harvesting

Piezoelectric materials are widely used in electromechanical energy conversion, such as in sensors, transducers, and self-powered materials. In this paper, the influence of the Sm doping content on the microstructure and ferroelectric, piezoelectric, dielectric, and field-induced strain properties of 0.70Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ (PMN-PT) ceramics was investigated. Sm-doped PMN-PT ceramics with both high piezoelectric properties (d₃₃～1406 pC/N) and a large electromechanical coupling coefficient (k_p～0.69) were synthesized. Based on their piezoelectric effect, a maximum output voltage of 31 V was achieved under external forces. The output voltages showed satisfactory stability, repeatability, and sensitivity under periodic external forces; hence, Sm-doped PMN-PT piezoelectric ceramics are potential candidates for energy conversion and signal monitoring.