O3 Lead-free Piezoelectric Ceramics Research Articles

The structural evolution and electric field-induced strain performance of Bi0.5(Na0.41K0.09)TiO3–Ba(Fe0.5Sb0.5)O3 lead-free piezoelectric ceramics

The structural evolution and electric field-induced strain performance of Bi0.5(Na0.41K0.09)TiO3–Ba(Fe0.5Sb0.5)O3 lead-free piezoelectric ceramics

Design of highly active and stable (K0.48Na0.48Li0.04)(Nb0.975Sb0.025)O3–(Bi0.5Na0.5)(Zr0.8Ti0.2)O3 lead–free piezoelectric ceramics by constructing rhombohedral–tetragonal phase boundaries at room temperature

Design of highly active and stable (K0.48Na0.48Li0.04)(Nb0.975Sb0.025)O3–(Bi0.5Na0.5)(Zr0.8Ti0.2)O3 lead–free piezoelectric ceramics by constructing rhombohedral–tetragonal phase boundaries at room temperature

Giant piezoelectric response and structure evolution of Bi0.5(Na0.3K0.3Li(0.4-x)Bax)0.5ZrO3 modified (K0.48Na0.52)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

Giant piezoelectric response and structure evolution of Bi0.5(Na0.3K0.3Li(0.4-x)Bax)0.5ZrO3 modified (K0.48Na0.52)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

A Rotary-Linear Ultrasonic Motor Using MnO2-Doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 Lead-Free Piezoelectric Ceramics with Improved Curie Temperature and Temperature Stability

In this work, a cylindrical lead-free rotary-linear ultrasonic motor was attached to piezoelectric plates of MnO2-doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 ceramics using the first bending vibration to pull a thread output shaft of the interior of a stator. The effect of the proposed ceramics’ d33 and Qm values are the key factors for ultrasonic motors. Therefore, MnO2-doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 lead-free piezoelectric ceramics with high values of d33 = 230 pC/N, Qm = 340.8 and a good temperature stability of their dielectric and piezoelectric properties are suitable for application to linear piezoelectric motors. The structure of the linear piezoelectric motor was simulated and fabricated by Finite Element Analysis. The characteristics of linear piezoelectric motors were also studied. The output characteristics of the lead-free piezoelectric motor were a left-pull velocity = 3.21 mm/s, a right-pull velocity = 3.39 mm/s, an up-pull velocity = 2.56 mm/s and a force >2 N at 39.09 kHz for an input voltage of approximately 200 Vp-p (peak to peak). These results are comparable to those for a lead-based piezoelectric motor that uses PZT-4 ceramics. The proposed lead-free piezoelectric motors were successfully fabricated and used to pull a 0.5 mL commercial insulin syringe.

Effect of Different Ca2+ and Zr4+ Contents on Microstructure and Electrical Properties of (Ba,Ca)(Zr,Ti)O3 Lead-Free Piezoelectric Ceramics

In the preparation of (Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric ceramics, different Ca2+ and Zr4+ contents will greatly affect the phase structure, microstructure, and electrical properties of the ceramics. XRD shows that all samples have pure perovskite phase structure, and the (Ba0.85Ca0.15)(ZryTi1−y)O3 ceramics morphotropic phase boundary region from tetragonal phase to rhombohedral phase near 0.08 ≤ y ≤ 0.1. From the dielectric temperature curve, the phase transition temperature (TO-T) was found near room temperature at 0.12 ≤ x ≤ 0.18 for the (Ba1−xCax)(Zr0.1Ti0.9)O3 ceramics. Both Ca2+ and Zr4+ increase have a significant decrease on the Curie temperature Tc. All samples were revealed as relaxers with diffusivities in the range 1.29 ≤ γ ≤ 1.82. Different from the undoped ceramics, ceramics doped with Ca and Zr ions exhibit saturated P–E hysteresis loops, and their ferroelectric properties are significantly optimized. In particular, the (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic demonstrated optimal properties, namely d33 = 330 pC/N, kp = 0.41, εr = 4069, Pr = 4.8 μC/cm2, and Ec = 3.1 kV/cm, indicating that it is a viable lead-free piezoelectric contender. Variations in Ca and Zr content have a significant effect on the crystal grain sizes and densities of ceramics, which is strongly associated with their piezoelectricity.

Crystal Structure, Microstructure and Electrical Properties of (Ba0.97Ca0.03)(Ti0.94-xMnxSn0.06)O3 Ceramics Synthesized by the Solid State Combustion Technique

This research studied the effect of MnO2 substitution on the phase formation, microstructure and electrical properties of (Ba0.97Ca0.03)(Ti0.94-xMnxSn0.06)O3 (BCTMS with x = 0, 0.005, 0.010, 0.015, and 0.020 mol%) lead-free piezoelectric ceramics. The BCTMS ceramics were fabricated by the solid-state combustion technique. The powders and green pellets were calcined and sintered at 1100 °C for 4 h and 1400 °C for 2 h, respectively. The XRD patterns of all BCTMS ceramics exhibited a single perovskite structure with the coexisting orthorhombic and tetragonal phases, where the tetragonal phase increased and the orthorhombic decreases with increasing x. The average grain size decreased from 35 to 13 µm with increasing x. The dielectric constants at room temperature (ε r) and at the Curie temperature (εC ), density, remanent polarization (Pr ), and piezoelectric coefficient (d33 ) decreased as x increased. The changes in the crystal structure and microstructure affected electrical properties.

Photoluminescence in Sm3+ activated 0.92(Na0.5Bi0.5)TiO3-0.08(Ba0.90Ca0.10)(Ti0.92Sn0.08)O3 multifunctional lead-free ferroelectric ceramics for non-contact optical thermometry

A series of Sm 3+ doped 0.92(Na 0.5 Bi 0.5 )TiO 3 -0.08(Ba 0.90 Ca 0.10 )(Ti 0.92 Sn 0.08 )O 3 (NBT-8BCTS: x Sm 3+ , x = 0–0.025) lead-free piezoelectric ceramics are fabricated via a conventional solid-state reaction method, and their phase structure, photoluminescence properties and temperature dependent of luminescence spectra are studied in detail. The emission spectra with dominant orange-red emission consist of four emission peaks at 542 nm, 598 nm, 644 nm and 709 nm, which are ascribed to the 4 G 5/2 → 6 H J/2 (J = 5, 7, 9, 11) transition of Sm 3+ ions, respectively. Furthermore, the optical temperature sensing properties of the NBT-8BCTS: 0.01Sm 3+ ceramic in the temperature range between 313 K and 533 K are analyzed with a maximum relative sensitivity 1.29%K −1 at T = 463 K. Besides, the phosphors exhibit excellent stable temperature sensing performance under repeated heat-cooling cycles. These results suggest that the Sm 3+ doped NBT-8BCTS ceramics may have potential applications in multifunctional sensing devices by integrating its optical temperature sensing and intrinsic ferroelectric property. • Ferroelectricity and photoluminescence emissions coexist in NBT-BCTS: x Sm 3+ . • A maximum relative sensitivity of 1.29% K −1 at 463 K is obtained. • Sm doped NBT-BCTS ceramics have potential for developing multifunctional optical-electric devices.

Doping effects in (Ba0.85Ca0.15)(Hf0.1Ti0.9)O3 lead-free piezoelectric ceramics prepared via powder injection moulding using simple binder

To improve densification of the (Ba0.85Ca0.15)(Hf0.1Ti0.9)O3 (BCHT) ceramics prepared via powder injection moulding, MnO2 and Li2CO3 were used as sintering aids. The BCHT ceramics doped with different Mn- and Li-amount prepared by powder injection moulding in which paraffin was used as injection binder, have rather pure perovskite structure with complicated polymorphic ferroelectric phase coexistence. Polyhedral grains combined with nearly round shape grains with increased relative density and larger gains size were obtained at appropriate doping amount, related to the formation of liquid phase during sintering and increased mobility of ions due to the generation of point defects caused by heterovalent cations doping. TheMn- and Li-doped BCHT ceramics are displacement driven ferroelectrics with apparent diffused transition characteristic at different extent, relating to the morphotropic phase boundary composition and the variation of point defects induced by doping. Comparable or surpassing electrical performance was acquired, especially the dielectric breakdown strength was increased due to the improved sinterability. With appropriate doping amount, piezoelectricity larger than 300 pC/N can be obtained in the Mn- and Li-doped BCHT ceramics poled under low electric field.

Enhanced electrical properties of lead-free (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 piezoelectric ceramics by optimizing phase ratio and sintering temperature

It is challenging for material chemists to develop lead-free ceramics due to the toxicity of lead for human health and environment. (Ba, Ca)(Ti, Zr)O3 and (Ba, Ca)(Ti, Sn)O3 lead-free piezoelectric ceramics have attracted much attention due to their superior piezoelectric properties. In this study, Ca2+, Zr4+ and Sn4+ were simultaneously doped at A-sites and B-sites, respectively, to clarify the structure and enhance the electrical performance. (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 (BCxTZS) lead-free piezoelectric ceramics were successfully fabricated by conventional solid-state reactive sintering method. The effects of Ca2+ content (x) and sintering temperature on microstructure, phase structure and electrical properties of BCxTZS were investigated. Herein, BCxTZS ceramics are the coexistence of R-O phases as 0.01 ≤ x ≤ 0.02, and they become O-T phases as 0.02 < x ≤ 0.08. The excellent electrical performances with d33 = 511 pC N−1, kp = 43% and Qm = 126 were achieved by optimizing the phase ratio and sintering temperature. The superior d33 along with the comparable Qm with PZT ceramics indicates that BCxTZS ceramics are promising lead-free piezoelectric ceramics.

Synthesis and characterization of MnO2 added (Na0.475K0.475Li0.05)(Nb0.9Ta0.05Sb0.05)O3 lead-free piezoelectric ceramics

Lead-free NKLNTS ceramics with promising piezoelectric properties were fabricated using the solid phase method, which is a general ceramic manufacturing method. MnO2 was added to NKLNTS ceramics as a sintering aid to improve piezoelectric and dielectric properties. The added MnO2 content was adjusted to 0, 0.1, 0.3, 0.5, and 0.7 wt%, the powder was calcined at 900 °C for 2 h, and then the sintering temperature was changed from 1000 to 1100 °C to study the optimum temperature and composition that yields excellent piezoelectric properties and sinterability. Archimedes method and scanning electron microscope (SEM) were used to evaluate the sinterability, X-ray diffraction analysis (XRD) was performed to confirm the crystallinity of the sintered body, and piezoelectric and dielectric properties were evaluated using a d33-meter and an impedance analyzer. When 0.1 wt% of MnO2 was added, it was confirmed that density was the highest at the sintering temperature of 1050 °C and had excellent piezoelectric and dielectric properties. When 0.3 wt% or more of MnO2 was added, piezoelectric and dielectric properties were decreased due to the decreased density. When NKLNTS-0.1wt% MnO2 was sintered at a sintering temperature of 1050 ℃ for 2 h, it had a density of about 97%. Furthermore, lead-free piezoelectric ceramics with excellent piezoelectric and dielectric properties of d33 = 271 pC/N, kp = 0.40, er = 1250, tan δ = 2.5%, and Tc = 348 °C were fabricated.

Preparation and electrical performance of BCHT lead-free piezoelectric ceramics via powder injection molding

(Ba0.85Ca0.15)(Hf0.10Ti0.90)O3 (BCHT) lead-free piezoelectric ceramics were synthesized via the powder injection molding process sintered at several temperatures, in which the BCHT ceramics were prepared by the conventional ceramic processing sintered at the optimized temperature 1450 °C for comparison. All the synthesized BCHT ceramics exhibit rather pure perovskite phase structure, where the BCHT ceramics prepared via the powder injection molding process present more apparent multiphases coexistence characteristic. The electrical properties of the BCHT ceramics prepared via the powder injection molding process are slightly better than those prepared by the solid-state sintering method, which correlate with the increase of ceramics densification and the change of grains micro-morphology. The powder injection molding technique provides a feasible way to synthesize irregular shaped piezoelectric ceramics with excellent electrical performance.

Ca2+ doping effects in (K, Na, Li)(Nb0.8Ta0.2)O3 lead-free piezoelectric ceramics

Lead-free (K0.5-x/2Na0.5-x/2Lix)(Nb0.8Ta0.2)O3 (KNLNT) and (K0.49-x/2Na0.49-x/2-LixCa0.01)(Nb0.8Ta0.2)O3 (KNLNT-Ca) ceramics were prepared by a conventional ceramic processing. Structural analysis shows that the Ca2+ doping takes the A site of ABO3 perovskite and decreases the phase transition temperature. Property measurements reveal that as a donor dopant, the Ca2+ doping results in higher room-temperature dielectric constant, lower dielectric loss, and lower mechanical quality factor. In addition, the Ca2+ doping does not change the positive piezoelectric coefficient d33, but increases the converse piezoelectric coefficient d33* significantly. This is likely due to the increase in the relaxation, as well as the appearance of (CaNa/K·-VNa/K’) defect dipoles.

Strong piezoelectricity of Li2CO3-doped BiFeO3–BaTiO3–Bi(Zn0.5Ti0.5)O3 lead-free piezoelectric ceramics with high Curie temperature and high temperature stability

Abstract BiFeO3–BaTiO3–Bi(Zn0.5Ti0.5)O3+xLi2CO3 (BFBT-BZT-xLC) lead-free piezoelectric ceramics with high Curie temperature and high temperature stability were made by refined solid-state reaction approach. More specifically, the phase transformation, microstructure, electric properties and high temperature stability of the ceramics were well studied. Experimental results demonstrate that piezoelectric properties and temperature stability of BFBT-BZT-xLC piezoelectric ceramics were significantly improved by adding Li2CO3 sintering additives. What’s more, when x = 0.3 mol% the ceramics sintered at 970 °C, the results show the optimal electrical properties with kp = 0.357, Qm = 35.687, tanδ = 0.043, d33 = 184 pC/N. In particular, high Curie temperature (TC = 554 °C) and high depolarization temperature (Td = 530 °C, d33 = 150 pC/N) were obtained. Therefore, the results show that BFBT-BZT-xLC ceramics are a promising high temperature lead-free piezoelectric ceramic material.

Electrical Properties of Ba0.96Ca0.04Ti0.90Sn0.10O₃ Lead-Free Ceramics with the Addition of Nano-CeO₂.

Well dispersed CeO₂ nanoparticles are prepared by azeotropic co-precipitation method. (Ba0.96Ca0.04)(Ti0.90Sn0.10)O₃ lead-free piezoelectric ceramics doped with nano-CeO₂ (x =0 mol%, 0.03 mol%, and 0.07 mol%) and micro-CeO₂ (x = 0.03 mol%) are prepared at 1430 °C for 2 h by the conventional solid state sintering method. XRD diffraction indicates that all components have typical perovskite structure. Both doping of nano-CeO₂ and micro-CeO₂ can inhibit grain growth. And the average grain size decreased apparently with the increase of nano-CeO₂ amount. All the samples exhibit typical diffuse phase transition behavior. The optimized electrical performances are obtained at x = 0.03 mol% with d33 = 512 pC/N, kp = 41.5%, and Pr = 14.00 μC/cm².

Bi0.48(Na0.84K0.16)0.48Sr0.04(Ti1-xTax)O3 lead-free ceramics with enhanced electric field-induced strain

Abstract A series of Bi0.48(Na0.84K0.16)0.48Sr0.04(Ti1-xTax)O3 (abbreviated as NKS-100xTa) lead-free piezoelectric ceramics were fabricated using a traditional solid-state method. The structure and electrical properties of NKS-100xTa were investigated in detail. The composition for x = 0.01 presented an enhanced electric field induced bipolar strain of ∼0.53%, as well as the giant unipolar strain of ∼0.478% corresponding to Smax/Emax ∼682 p.m./V at 70 kV/cm. It is found that the ferroelectric-relaxor transition temperature (TF-R) shifted down to ambient temperature and the remnant polarization (Pr) decreased with the Ta doping. It destroyed the long-range ferroelectric ordering and increased the relaxor characteristic. Therefore, the origin of giant strain was ascribed to the transformation from the ferroelectric phase to relaxor phase under the applied electric field. In addition, the well fatigue properties within 104 cycles indicated that the prepared ceramics offered extendable availability for sensors and actuators.

Grain size dependence of the microstructures and functional properties of (Ba0.85 Ca0.15–x Cex) (Zr0.1 Ti0.9) O3 lead-free piezoelectric ceramics

ABSTRACTBy the solid-state reaction route, (Ba0.85Ca0.15-x Cex) (Zr0.1Ti0.9) O3 (BCCeZT) lead-free piezoelectric ceramics were prepared. The powder was processed at 1250 ºC for 2 h, and compacted green bodies were then sintered at various sintering temperatures. X-ray diffraction analysis and Raman spectra confirmed the rhombohedral-tetragonal phase coexistence of x = 0–0.00131. Addition of CeO2 facilitated development of grain sizes greater than 10 μm at low sintering temperatures. The effects of grain size on the ferroelectric and piezoelectric properties were studied systematically and it was found that a ~ (10–12) μm grain size is critical for the processing of high-performance lead-free BCCeZT ceramics. CeO2 substitution at the A site may bring down the sintering temperature by about 200 °C without significant loss of properties. The best properties were obtained for x = 0.00131 at a low sintering temperature of 1350°C for 4 h exhibiting d33 = 501 ± 10 pC/N, kp = 38.5 ± 1.92 %, Pr = 12.19 μC/cm2, TC = 108.1°C, and a large strain of 0.14%. These results show that BCCeZT ceramics could be promising candidates for the fabrication of lead-free devices.

Enhanced Curie temperature and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3 lead-free ceramics after the addition of LiTaO3

Abstract Polycrystalline (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3–xLiTaO3 ceramics were designed and synthesized using a solid-state reaction to improve both the Curie temperature and the electrical properties of (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3 lead-free piezoelectric ceramics. The effect that the addition of LiTaO3 has on the structure and electrical properties of BCZT ceramics was studied systemically. The results show that the Curie temperature and the piezoelectric properties of BCZT can be substantially enhanced by adding LiTaO3. The Curie temperature increased from 93 °C to 102 °C after adding LT of 0.3 mol.%. X-ray diffraction and Raman spectral analysis of the ceramics reveal the coexistence of orthorhombic (O) and tetragonal (T) phases. This coexistence of O and T phases at room temperature helps improve the ferroelectric and piezoelectric properties. The ceramic with x = 0.3 mol.% exhibits the highest values for d33 = 433 pC/N, d 33 * = 858 pm/V (at 1 kV/mm) and kp = 44.6%. Furthermore, giant electrostrictive coefficients (Q33 ≈ 0.040–0.050 m4/C2) were also obtained for these LT-doped BCZT ceramics. These properties confirm that BCZT-xLT is a promising candidate system for lead-free piezoelectric ceramic materials.

Enhanced dielectric and ferroelectric behavior in 0.94BNT-0.06BCTS lead free piezoelectric ceramics synthesized by the solid state combustion technique

ABSTRACTIn this study, the effects of calcination temperature (600–900°C for 2 h) and sintering temperature (1100–1200°C for 2 h) on phase formation, microstructure and electrical properties of new 0.94(Bi0.5Na0.5TiO3)-0.06(Ba0.945Ca0.055)(Ti0.91Sn0.09)O3 (0.94BNT-0.06BCTS) lead-free piezoelectric ceramics were investigated. These ceramics were fabricated by the solid state combustion technique using glycine as fuel. It was found that single perovskite phase of 0.94BNT-0.06BCTS powders is obtained by the sample calcined at 650°C for 2 h. The microstructure of the 0.94BNT-0.06BCTS powders showed an almost-circle shape and the average particle size increased from 218 to 298 nm when the calcination temperature was increased from 600 to 900°C. The XRD pattern of all ceramics presented a single perovskite structure with the co-existence of the rhombohedral and tetragonal phase. The average grain size increased with increasing sintering temperature. The density, dielectric constant (at Tr and Tm) and piezoelectric constant (d33) increased when sintering temperature was increased up to 1150°C and then, reduced in values, respectively. At a sintering temperature of 1150°C, 0.94BNT-0.06BCTS ceramic exhibited the highest density (5.95 g.cm−3), the highest dielectric constant at Tm (ϵmax = 6210), the strongest ferroelectric properties (Pr = 43.4 μC/cm2 and Ec 37.68 kV/cm) and the highest d33 value (189 pC/N). The large ferroelctricity in 0.94BNT-0.06BCTS ceramic make them good candidates for lead-free practical applications as a ferroelectric capacitor.

Effects on structure and properties of BCZT lead-free piezoelectric ceramics by rare-earth doping

ABSTRACT1 mol% rare-earth element doped [(Ba0.85Ca0.15)0.99Re0.01](Zr0.1Ti0.9)O3 (BCZT-Re, Re = La, Sm, Yb, Eu and Er) lead-free piezoelectric ceramics were prepared by the conventional ceramic processing using high-purity carbonates and oxides as raw materials. The BCZT-Re ceramics sintered at 1450°C exhibit pure rhombohedral perovskite structure approaching the morphotropic phase boundary (MPB) composition accompanied by different relative density and grain size distribution. The dielectric behavior of the BCZT-Re ceramics approaches normal ferroelectrics but with slightly broad dielectric response peaks, and can be fitted well by the Curie-Weiss law above the Curie temperature TC but in a limited temperature range. Besides the La doping, the other BCZT-Re ceramics present symmetric and saturated P-E hysteresis loops, in which the BCZT-Eu ceramics exhibit apparently large values of polarization remnant Pr and coercive field Ec. The Pr and Ec values decrease rapidly around 80–90°C, depending on compositions, in the BCZT-Re ceramics, determining their safe use temperatures. Excellent fluorescence performance with different photoluminescence emission intensity and light color is induced by the rare-earth doping in the BCZT-Re ceramics, which can meet the requirements of the multifunctional applications using the ferroelectric-based materials.

Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 lead-free piezoelectric ceramics with high Curie temperature

In this work, the process of two-stage modifications for (Ba0.97Ca0.03)(Ti0.96Sn0.04-xHfx)O3 (BCTS4-100xH100x) ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification) which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC) of about 112 °C, a piezoelectric charge constant (d33) of 313 pC/N, an electromechanical coupling factor (kp) of 0.49, a mechanical quality factor (Qm) of 122, and a remnant polarization (Pr) of 19μC/cm2. In addition, the temperature stability of the resonant frequency (fr), kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C) was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn) piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ∼ 0.39, d33 ∼ 230 pC/N, Qm ∼ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.