Large Field-induced Strain Research Articles

Origin of the ultrahigh field-induced strain in the Gd-doped 0.854Bi0.5Na0.5TiO3-0.12Bi0.5K0.5TiO3-0.026BaTiO3 ternary ceramic system

This study focused on analyzing the ferroelectric, piezoelectric, and dielectric properties of lead-free Bi0.487Na0.427K0.06Ba0.026TiO3 (0.854BNT-0.12BKT-0.026BT) ternary ceramic system by systematically doping 0.001, 0.01, 0.1, 0.5, and 1.0 mol% Gd2O3. The specific composition that was investigated is located at the tetragonal side of the rhombohedral-tetragonal morphotropic phase boundary (MPB) region. Undoped and Gd-doped BNT-BKT-BT ceramics were produced by the conventional solid-state reaction method. Ferroelectric, piezoelectric, and dielectric properties of ceramics were analyzed by carrying out electrical measurements from sintered samples. An ultrahigh field-induced unipolar strain of 0.52% at 65 kV cm−1, with a converse piezoelectric coefficient d33* of up to 795 pm V−1, was achieved with 0.5 mol% Gd doping. This was attributed to the Gd dopant disrupting the normal ferroelectric order and leading to the formation of a nonpolar relaxor phase. The field-induced transition from the nonpolar relaxor phase to the normal ferroelectric phase resulted in relatively large field-induced strain values in the 0.5 mol% Gd-doped ceramics. These results suggest that Gd-doped BNT-BKT-BT ceramics hold promise for digital actuator applications.

Phase stability and physical property for off-stoichiometric Ni-Mn-Sb alloys including 4O phase

Large magnetic field-induced strains can only be found in modulated martensite for Ni-Mn-Sb alloys, but the theoretical research on this alloy which is generally concentrated in the austenite and non-modulated martensite (NM) ignores the modulated martensite. Therefore, in this paper, we systematically study the relationship between phase stability, physical property and composition in the full series Ni-Mn-Sb Heusler alloys (Ni24+xMn12-xSb12, Ni24+xMn12Sb12-x, Ni24-xMn12+xSb12, Ni24Mn12+xSb12-x) including four-layered orthorhombic modulated martensite (4O) by the first principles calculations. For phase stability, we determined that the critical components of 4O for Ni24+xMn12-xSb12, Ni24+xMn12Sb12-x and Ni24Mn12+xSb12-x is × = 6, x = 6 and × = 4, respectively. There is no 4O phase within the concentration range considered for Ni24-xMn12+xSb12. Moreover, the martensitic transformation sequences are also determined. As for physical properties, the transformation temperatures from austenite to 4O and NM phases are predicted respectively. Meanwhile, the ternary magnetic moment diagram of austenite, 4O and NM phases is constructed. The maximum value of total magnetic moment is distributed in the Ni-excess Sb-deficient system, while the minimum value of that is distributed in the Mn-excess Sb-deficient system. The origin of the above observations is explained by the competition between the Jahn-Teller effect in the electronic structure and the strength of the covalent bond. The results in this paper are expected to provide information for the composition design and performance optimization of Ni-Mn-Sb alloy.

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(In1/2Nb1/2)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(In1/2Nb1/2)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 Hy 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.

Electric field-induced large strain and photoluminescence properties in SrRECoO4 (RE = Pr, Eu, Sm)-modified BNT-based ferroelectric ceramics

(1-x) (0.935BNT–0.065BaTiO3)-xSrRECoO4 (BNBT6.5-xSREC, RE = Pr, Eu, Sm)–based lead-free ferroelectric ceramics with large electrostrain and photoluminescence effect were prepared in our work. Through introducing the SREC dopant into BNBT6.5, the long-range ferroelectric order of ceramics was disrupted, inducing a weak polar state dominated by polar nanoregions before applying an electric field. Due to the reversible transition of PNRs under the electric field, the electrostrain was greatly promoted. When the content of SREC was 0.012, large field-induced large strains of 0.38–0.44% were obtained under an electric field of 70 kV/cm, equivalent to a large signal d33* (Smax/Emax) of 543–586 pm/V. Moreover, relying on the luminescence effect of RE3+ ions in SREC, the modified ceramics exhibited strong photoluminescence with bright red or orange emissions, depending on the type of RE elements. However, the strong emission was strongly quenched in samples with a higher SREC content due to the photoluminescence quenching effect of the heavy metal (Co3+) ions in the SREC dopant. The quenching model can be based on the formation of non-radiative recombination centers induced by Co3+ ions, which affect the energy transition of RE3+ ions from the excited state to the ground state.

Ultrahigh piezoelectric performance benefiting from quasi-isotropic local polarization distribution in complex lead-based perovskite

Materials with high piezoelectricity have always been the pursuit of both industrial production and scientific research. Designing new high-piezoelectricity materials and establishing the structure-performance relationship are crucial for those two aspects. Here, a complex perovskite system with excellent comprehensive properties (d33 = 920 pC/N, d33* = 902 pm/V, Tm = 120 °C, kp = 0.62) is developed, and taken as a case study to explain the origins of high piezoelectricity utilizing atomic-resolution scanning transmission electron microscopy and in situ high-energy synchrotron X-ray diffraction. Correlated local multiple polar symmetries coexistence with a quasi-isotropic local polarization distribution result in a long-range average pseudo-cubic phase. The reduced local polarization anisotropy and the flexible polarization configuration promote a continuous polarization rotation between different polarities, leading to a large field-induced lattice strain and ultimately generating high piezoelectric performance. This work provides a perspective that decreased polarization anisotropy at the local scale is beneficial to the enhancement of high piezoelectricity, which will facilitate the design and development of new piezoelectric materials.

Enhanced large field-induced strain and energy storage properties of Sr0.6La0.2Ba0.1TiO3-modified Bi0.5Na0.5TiO3 relaxor ceramics

Enhanced large field-induced strain and energy storage properties of Sr0.6La0.2Ba0.1TiO3-modified Bi0.5Na0.5TiO3 relaxor ceramics

Unraveling the Phase Stability and Physical Property of Modulated Martensite in Ni2Mn1.5In0.5 Alloys by First-Principles Calculations.

Large magnetic field-induced strains can be achieved in modulated martensite for Ni-Mn-In alloys; however, the metastability of the modulated martensite imposes serious constraints on the ability of these alloys to serve as promising sensor and actuator materials. The phase stability, magnetic properties, and electronic structure of the modulated martensite in the Ni2Mn1.5In0.5 alloy are systematically investigated. Results show that the 6M and 5M martensites are metastable and will eventually transform to the NM martensite with the lowest total energy in the Ni2Mn1.5In0.5 alloy. The physical properties of the incommensurate 7M modulated martensite (7M–IC) and nanotwinned 7M martensite () are also calculated. The austenite (A) and phases are ferromagnetic (FM), whereas the 5M, 6M, and NM martensites are ferrimagnetic (FIM), and the FM coexists with the FIM state in the 7M–IC martensite. The calculated electronic structure demonstrates that the splitting of Jahn–Teller effect and the strong Ni–Mn bonding interaction lead to the enhancement of structural stability.

Investigation on the Role of Polypyrrole/Carbon Black Nanoparticles in the Electromechanical Behavior of Modified P(VDF-HFP)

Recently, the polyvinylidenefluoride-co-hexafluoropropylene P(VDF-HFP) as electroactive polymers (EAPs) has been known to have great potentials in micro electro mechanical systems (MEMs) due to their light weight, low cost, and large electrical field-induced strain. In order to enhance their electromechanical properties, the modified P(VDF-HFP) with various conducting polymers such as polypyrrole (PPy) and carbon black (CB) is considerably required. In this work, the P(VDF-HFP) as matrix was doped with different loading of PPy/CB (< 1 wt%) and the composites films were obtained by using solution casting method. The influence of filler content on the dielectric properties and the conductivity of these thin films was investigated by using LCR meter. The maximum dielectric constant of the P(VDF-HFP)/PPy-CB was 2 times larger than the pure P(VDF-HFP) without conductive fillers. At low frequency, the both dielectric loss and conductivity were found to be slightly increased as consequence of the conducting polymers, but the conductive phase has not been achieved yet. In addition, a complete set of electromechanical properties were systemically explored using the result of strain displacement under the low electric field (< 5 MV/m). During the applied electric field, the average voltage peak-to-peak was attributed to the strain yield of approximately 0.08% at 2 MV/m. These observations indicate that the synergistic effect of conductive fillers induce their electric polarization and it can be considered as one of the promising candidates for actuator applications.

Giant strain with ultra-low hysteresis by tailoring relaxor temperature and PNRs dynamic in BNT-based lead-free piezoelectric ceramics

State-of-the-art ferroelectric materials with large field-induced strain together with low hysteresis are required in high precision or positioning devices. However, the high electro-strain is always suffered from a large strain hysteresis, severely restricting its practical application. In this study, the relaxor temperature (Tf) of BNT-6BT near the morphotropic phase boundary with initially high polarization was adjusted to near room temperature by adding Sr0.7La0.2TiO3. The room temperature relaxation properties feature with the high dynamic polar nanoregions with moderate polar spatial correlations, which paired the high strain (0.325%) and ultra-low hysteresis (8.02%). This actuation strain is superior to those of previously reported lead-free piezoelectric materials. Meanwhile, the strain responses also displayed outstanding temperature and frequency stability from 30°C to 150 °C and 1 Hz–25 Hz, respectively, indicating its practical application potential. The results will provide new insight into the design of high-performance BNT-based ceramics for use in actuators.

Large field-induced strain with enhanced temperature-stable dielectric properties of AgNbO3-modified (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics

(1-x)(Bi0.5Na0.5)0.94Ba0.06TiO3-xAgNbO3 lead-free piezoelectric ceramics (abbreviated as BNBT-100xAN) were prepared using the conventional solid-state sintering method. The effects of the introduction of AgNbO3 (AN) dopants for the dielectric and piezoelectric performances of BNBT-100xAN ceramics were systematically studied. The XRD patterns and Raman spectra demonstrated that AN as a modifier was successfully diffused into the BNBT-100xAN lattice and revealed a pseudo-cubic symmetry structure. All samples exhibited a dense surface morphology accompanied by the uniform distribution of elements. A large bipolar strain of ~0.501% and unipolar strain of ~0.481% corresponding to the normalized strain d33* of ~740 p.m./V were achieved for BNBT-1AN ceramic at 65 kV/cm field. The BNBT-4AN ceramic exhibited an excellent temperature-stable permittivity with the range from 59 to 380 °C and its dielectric loss was less than 0.02 between 97 °C and 329 °C. These results revealed that BNBT-100xAN ceramics were more hopeful candidates for actuators, strain sensors, and high-temperature capacitors.

Origin of the Large Field-Induced Strain and Enhanced Energy Storage Response of Rare-Earth-Doped Lead-Free 0.854BNT-0.12BKT-0.026BT Ceramics.

In this study, effects of rare-earth elements such as Nd, Gd, and Ce on the structural and electrical properties of lead-free bismuth sodium potassium barium titanate Bi0.487Na0.427K0.06Ba0.026TiO3 (0.854BNT-0.12BKT-0.026BT) (BNKBT) ceramics have been investigated in detail. Solid-state reaction method was used to prepare undoped, 1.0 mol% Nd, 1.0 mol% Gd, 1.0 mol%, 2.1 mol%, and 2.7 mol% Ce-doped BNKBT ceramic powder compositions. A pure single perovskite structure was observed in the X-ray diffraction (XRD) patterns for all the BNKBT ceramic systems, although doping was found to cause changes in peak splitting and peak positions due to their site preference. The Curie temperatures have not shifted significantly with doping, but the relative permittivity values were found to have increased. The nonergodic normal ferroelectric character of undoped BNKBT ceramic switched to an ergodic relaxor character at room temperature with Nd, Gd, and Ce doping with pinched polarization vs electric field hysteresis loops. Increased field-induced strain levels were observed in the doped BNKBT ceramics with 1 mole% Ce doping yielding a giant field-induced strain of 0.38% under an E -field of 65 kV/cm. Nd-doping, on the other hand, resulted in the highest releasable energy density of 0.64 J/cm3 at 65 kV/cm. Consequently, the rare-earth-doped BNKBT ceramics were found to be promising for both digital actuator and high-energy-density capacitor applications due to their favorable electrical properties.

Large electric-field-induced strain and energy storage properties in Bi0.5Na0.5TiO3-(0.5Ba0.7Ca0.3TiO3-0.5BaTi0.8Zr0.2O3) lead-free relaxor ferroelectric ceramics

Piezoelectric ceramics with high strain can convert electrical energy and mechanical energy into each other for a wide range of applications. (1-x)Bi0.5Na0.5TiO3-x(0.5Ba0.7Ca0.3TiO3-0.5BaTi0.8Zr0.2O3) (BNT-x(BCT-BZT)) lead-free piezoelectric ceramics were prepared through solid-state reaction methods. The structural, dielectric, field-induced strain and energy storage properties of the ceramics were investigated systematically by various characterization techniques. A large field-induced strain of 0.42% with negligible negative strain and large reverse piezoelectric coefficient of 547 pm/V are obtained in BNT-9(BCT-BZT) ceramics. A large recoverable energy storage of 3.49 J/cm3 under 360 kV/cm and high energy storage efficiency of 64.9% are achieved in the BNT-10(BCT-BZT) ceramics. It believes that the large strain with negligible negative strain is mainly due to the crossover of relaxor nonpolar state to ferroelectric polar state. We believe that the BNT-x(BCT-BZT) ceramics are favorable for the practical applications in the mobile electronic devices.

Enhanced Bipolar Strain and Electrocaloric Response in Gadolinium/Tantalum Co-Substituted Sodium Bismuth Titanate Lead-Free Ceramics

High performance piezoelectric materials with an ABO3 perovskite structure have received growing attention in recent research due to their technological applications in sophisticated research, medical and defence devices like piezoelectric sensors, transducers, ultrasonic motors, nano-positioners, actuators and imaging devices, etc. The technical utility of these materials stems from the various possibilities they offer for cation substitution in the A (or) B sites, which provide valuable opportunities for the optimization and tailoring of desired properties. To date, lead based perovskites, such as lead zirconate titanate (PZT), PZN-PT, and PMN-PT materials, have been extensively investigated in the literature. Although lead based materials exhibit highest piezoelectric coefficients, their wide-scale application has often been hampered by considering the toxicity of lead and its effect on environment and health. This triggered the search for alternative materials that could replace the lead-based ceramics and results in less-hazardous production methods, use and recycling. This has led to a continuous search of potentially attractive alternative lead-free ceramic materials to their counterpart lead based materials for specific applications. Among various kinds of lead-free piezoelectric materials, Na0.5Bi0.5TiO3 (NBT)-based materials are considered to be promising candidates for replacing the lead-based materials. They have been extensively investigated by the condensed materials physics community because of their complicate phase transitions and superior piezo-response. Compared to various chemical substitutions, tantalum (Ta) substitution provides superior electro-strain for the NBT- based ferroelectrics, while the effect of tantalum oxide additive was rarely reported. Gd3+ and Ta5+ co-substituted (Na0.5Bi0.497Gd0.003)Ti1-xTaxO3 (NBGT-Tax) lead-free piezoelectric ceramics are synthesized by using hydrothermal technique. The influence of Ta5+ substitution on the sintering, microstructure, phase transition, and various electrical properties of NBGT ceramics was investigated. Tantalum substitution has no remarkable effect on the microstructure and densification within the studied doping composition. The X-ray diffraction studies revealed that both NBGT-Tax (x=0.000) and NBGT-Tax (x=0.003) ceramics exhibited single phases monoclinic crystal structure with Cc phase. However, with substitution of tantalum the antiferroelectric phase zone gets broader. Simultaneously, the temperature for a ferroelectric to antiferroelectric phase transition is reduced along with an increase in temperature for a transition from antiferroelectric phases to paraelectric phases. This results indicate that tantalum occupies B site of the perovskite structure behaving as a donor, producing A-site cation vacancies. The undoped NBGT ceramics shows good ferroelectric and piezoelectric properties (remnant polarization Pr = 34.2 μC/cm2). The value of remnant polarization was found to increase with Ta substitution along with an increase in coercive field as shown in the figure attached. This is because of the ferroelectric properties being influenced by composition and its homogeneity, defects, external field and orientation of domains, which eventually contributed to the materials response. Meanwhile, the addition of Ta leads to an increase in the electro-strain, together with a higher normalized strain. Moreover, the materials with temperature dependent polarization can be used for solid state cooling applications. The NBGT-Tax compositions shows decrement in the remnant polarization with the increasing temperature which causes increment in the change in entropy. Consequently, the material exhibits the conventional electrocaloric effect (ECE). This simultaneous presence of large field-induced bipolar strain and ECE response along with isothermal change in entropy opens window for great potential applications in the field of electronic devices. Figure 1

Enhancement of field-induced strain and bright upconversion luminescence in BNT-based multifunctional ceramics

In this work, a multifunctional lead-free (Bi0.5Na0.5)0.945Ba0.065Ti(1−x)(Fe0.5Sb0.5)xO3-0.005Er (BNBT-Er-xFS) ferroelectric material was prepared through the solid-state method, which has a large reversible field-induced strain of 0.465% (under an moderate electric field of 65 kV/cm) with a high normalized strain d33* (Smax/Emax) of 713 pm/V. Besides the excellent strain properties, this system also exhibits a bright green upconversion emission under excitation of 980 nm due to the luminescence characteristic of Er3+ ion. Moreover, the upconversion luminescence performance of BNBT-Er-xFS is enhanced with the (Fe0.5Sb0.5)4+ doping. At x = 0.0075, sample exhibited the strongest upconversion luminescence. As a multifunctional material, the BNBT-Er-xFS system is expected to be used in multifunctional electronic devices due to its excellent electrical and photoluminescence performance.

Enhanced relaxor behavior and thermal- and frequency-insensitive strain of (Na0.5Bi0.5)0.93Ba0.07Ti1 − x(Mn1/3Nb2/3)xO3 ceramics

(Na0.5Bi0.5)0.93Ba0.07Ti1 − x(Mn1/3Nb2/3)xO3 ceramics (x = 0–0.02) were prepared, and their structure and property were investigated systematically. (Mn1/3Nb2/3)4+ doping shifts ferroelectric–relaxor transition temperature (TF–R) toward low temperature. Thus, ferroelectric order is suppressed and relaxor behavior is enhanced monotonously, as further evidenced by composition-dependent electrical properties and domain evolution from labyrinthian to nanodomain. As a result, the x = 0.010 ceramic yields a large room temperature field-induced strain of 0.37%, especially the strain is temperature- and frequency-insensitive with a variety of 4.3% and 4.1% in the ranges of 25–125 °C and 0.5–10 Hz, respectively. This work suggests that the low content (Mn1/3Nb2/3)4+ complex cation doping is an alternative method to effectively tune the electrical properties of Na0.5Bi0.5TiO3-based ferroelectrics.

Large magnetic entropy change and magnetostrain in a directionally solidified Ni45.7Co4.2Mn37.3Sb12.8 alloy

Heusler-type Ni-(Co)-Mn-X (X = In, Sn, Sb) meta-magnetic alloys can exhibit various magneto-functional behaviors due to the strong coupling between the magnetic and structural orders. Here, we demonstrate large magnetocaloric effect and magnetic shape memory effect in a directionally solidified Ni45.7Co4.2Mn37.3Sb12.8 alloy with 〈5 5 3〉A preferred orientation. It is shown that large magnetic entropy change up to 27.4 J kg−1 K−1 can be achieved under the field change of 5 T. Moreover, a large magnetic field-induced strain of 0.42% was also obtained with no-prestrain through inverse martensitic transformation induced by applying a magnetic field of 7 T. The present magnetostain is much higher than those in polycrystalline Ni-(Co)-Mn-Sb based alloys reported previously. Such enhanced magneto-functional behavior could be attributed to the highly textured microstructure and enlarged lattice distortion through Co addition.

Double polarization hysteresis and dramatic influence of small compositional variations on the electrical properties in Bi4Ti3O12 ceramics

This work reports the existence of double polarization hysteresis (P–E) loop in Aurivillius-phase ferroelectric Bi4Ti3O12 (BiT) and reveals dramatic influence of small compositional variations on the electrical properties of it. The double polarization hysteresis is a characteristic of the interaction of defects with domain walls. This characteristic becomes more pronounced in Bi-deficient and Mg-doped BiT due to an increase in oxygen vacancy concentration at the lattices. Normal and saturated P–E loop is recalled by Nb donor doping, and associated composition Bi4Ti2.97Nb0.03O12.015 (BiT-0.03Nb) shows high remnant polarization (Pr = 12.5 μC/cm2) and large field-induced strain (S33 = 5.6 × 10−4). In addition, this doping results in bulk conductivity (σb) of BiT decreasing dramatically and associated activity energy (Ea) increasing significantly. In contrast, high oxide ion conductivity is induced with Mg2+ acceptor doping, and at 600 °C the optimum composition has ionic conductivity of ˜0.65 × 10−2 S cm−1 in the bulk.

Sr(Zn1/3Nb2/3)O3-induced R3c to P4bm transition and large field-induced strain in 0.80(Bi0.5Na0.5)TiO3–0.20SrTiO3 ceramics

Abstract

Electrical properties, defect chemistry and local lattice relaxation in Nb2O5 modified 0.94(Na0.5Bi0.5)TiO3–0.06BaTiO3 ferroelectrics

Single crystals of x at.% Nb + 0.94(Na0.5Bi0.5)TiO3–0.06BaTiO3 (x%-Nb:NBT-6BT, x = 0.12, 0.23, and 0.48) show improved ferroelectric and piezoelectric properties. In particular, the large piezoelectric constant (d33 = 532 pC/N) and high field-induced strains (Smax = 0.57%) in 0.23%-Nb:NBT-6BT single crystal demonstrate its promising application potential. The underlying mechanisms were investigated directively by atomistic scale simulations. We found that, Nb5+ cations prefer to substitute Ti4+ cations on B-site and will first fill up the oxygen vacancies generated due to the loss of Bi2O3 and/or Na2O. Higher concentration of Nb2O5, however, will be compensated by Ti and/or Bi vacancies. The ions positions surrounding the defect center(s) were identified.

Large field-induced strain, giant strain memory effect, and high thermal stability energy storage in (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric single crystal

(Pb,La)(Zr,Sn,Ti)O3 (PLZST) tetragonal antiferroeletric single crystals have been grown by conventional flux method. Phase structure, domain evolution, electric field-induced strain and energy storage properties of the as-grown PLZST crystals with [100] crystallographic orientation have been investigated systematically. A large electric field-induced strain up to 0.76% at 110 °C and a giant memory strain of 0.51% at 100 °C have been realized in the PLZST crystals. This field-induced strain has a nonlinear relationship with the square polarization, which simultaneously stems from the quadratic and higher order electrostrictions. Furthermore, a good thermal stability of energy storage performance with the recoverable energy variation less than 5% in a wide temperature window (105 °C) has been achieved. The combination of high strain and good thermal stability of energy storage wound make the PLZST crystals one of the most important candidates for high temperature electromechanical coupling and high reliability energy-storage devices.