Temperature- and electric-field-dependent electrical properties and nanoscale domain structures in PIN-0.49PMN-0.27 PT single crystal

The effect of temperature and electric field on phase transitions, dielectric relaxation behavior, and macroscopic electrical performances of Pb(In_1/2Nb_1/2)O₃-0.49 Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ (PIMNT27) single crystals were studied. The nanosized domains of unpoled crystals and the engineered domains of DC electric field poled crystals were intuitively recorded by piezoresponse force microscopy (PFM). The distribution of nanosized domains with different sizes and patterns induced by domain switching and domain wall motion under different poling fields and temperatures were also studied to understand the effect of nanosized domains on phase transitions, piezoelectric, and electromechanical properties.     

Domain Structure Evolution and Polarization Degradation of [101]‐Oriented 0.74Pb(Mg1/3Nb2/3)O3‐0.26PbTiO3 Single Crystal underCyclic Electric Loadings

The polarization degradation of ferroelectrics, reflected in the hysteresis loop as a decrease of remnant polarization, is a serious concern in applications. In situ observation of the polarization and domain structure evolution are carried out for [101]‐Oriented 0.74Pb(Mg_1/3Nb_2/3)O₃‐0.26PbTiO₃ (PMN‐26PT) single crystal under cyclic electric field. Measurements of the polarization hysteresis loops are conducted under a polarized light microscope (PLM), which is effective in detecting the domain structure of the single crystal. Prior to the polarization measurements, the crystal was poled. Upon cyclic electric field, reversal of monoclinic (M_B) takes place, and the phase transition from M_B to orthorhombic (O) phase occurs under positive field, but not under negative field of an electric cycle at a field magnitude up to 840 V/mm. The polarization loop is asymmetrical with the positive coercive field (+E_c) much less than the negative one (?E_c). As the field cycles, micro‐cracking occurs preferably in [101] direction, and a sudden drop appears in the curves of polarization versus number of cycles. Upon electric cycling at a field magnitude of 840 V/mm, the negative polarization increases slightly with the cycle number, indicating the rotation of a M_B phase toward the applied field direction.     

Dielectric relaxation and local domain structures of ferroelectric PIMNT and PMNT single crystals

Dielectric relaxation properties of ternary Pb(In_1/2Nb_1/2)O₃-0.49Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ (PIMNT27) and binary Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ (PMNT27) single crystals have been investigated. The dielectric constant peak temperature T_m with frequency obeys the Vogel-Fulcher (V-F) law. The dielectric constants at temperatures above T_m can be described by the Lorenz-type relationship. The fitting parameter δ_A and ΔT_m of PIMNT27 are higher than those of PMNT27, indicating stronger relaxation in ternary PIMNT system. Local nanodomain structures were measured by the piezoelectric force microscopy (PFM). The average autocorrelation function technique was applied to quantify these nanoscale domain patterns. The PIMNT27 exhibits smaller size nanodomains and shorter mean local short-range correlation length compared to PMNT27. The enhanced local disorder in PIMNT is related to the introduction of In³⁺ in PMNT system, which can enhance the disorder of B-site ions. In addition, the evolution of local polarization rotation under a step-increased tip dc voltage and the mean local short-range correlation length <ξ> as a function of dc voltage were obtained for both PIMNT27 and PMNT27 single crystals, which are crucial parameters for the understanding of the relationship between dielectric relaxation and local domain structures in relaxor-PbTiO₃ systems.     

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.     

Domain structure and evolution in ZnO-modified Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 ceramics

The doping of ZnO is efficient to improve the piezoelectric property and thermal stability of Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PMN–PT) based ceramics. However, the underlying physics, especially the local domain structures of the ZnO modified PMN–PT ceramics, which is strongly associated with the electric properties, is not clear yet. In this paper, we investigated the local domain structures and their evolution as a function of x in PMN–0.32PT:xZnO ceramics. It was found that, the domain evolution is mainly caused by the growth of grain size induced by the sintering aiding effect of ZnO at x < 0.04, and the domain evolution can be attributed to the phase transition induced by the partial replacement of Mg²⁺ by Zn²⁺ in the B-site of PMN–PT lattice at x > 0.06. Furthermore, we also investigated the domain structure evolution as functions of temperature and local external electric field in PMN–0.32PT:0.06ZnO ceramics, which exhibited superior piezoelectric property relative to other compositions. We found that the irregular nanodomains are more stable at high-temperature range, and the regular non-180° domains exhibited more complex rotation behavior under local electric field, which probably leads to the thermal stability and piezoelectric property enhancement in the ZnO-modified PMN–0.32PT ceramics.     

Dielectric relaxation properties of [001]c-, [011]c-, and [111]c-oriented 0.24PIN-0.47PMN-0.29PT single crystals

The dielectric relaxation properties and freezing behavior of polar nanoregions (PNRs) of 0.24Pb(In_1/2Nb_1/2)O₃-0.47Pb(Mg_1/3Nb_2/3)O₃-0.29PbTiO₃ single crystals have been studied. The Burns temperature T_B, permittivity maximum temperature T_m, and freezing temperature T_f were determined, respectively. It was found that the temperature-dependent dielectric constant can be well described by the Lorenz-type relationship in the ergodic phase due to the existence of PNRs. The diffuseness factor δ is >30 and is basically not dependent on crystal orientation. The frequency dependence of T_m obeys the Vogel-Fulcher relationship. The residual effect of the poling electric field disappears and the remnant polarization has a sharp decrease near the freezing temperature T_f.     

In Situ Domain Structure Observation and Giant Magnetoelectric Coupling for PMN‐PT/Terfenol‐D Multiferroic Composites

In situ observations of ferroelectric domain structure evolution, and magnetoelectric (ME) coupling are investigated for PMN‐28PT/Terfenol‐D (abbreviation of Pb(Mg_1/3Nb_2/3)O₃‐28PbTiO₃/Tb_0.3Dy_0.7Fe₂) and PMN‐33PT/Terfenol‐D composites under the magnetic loadings. The composite of PMN‐33PT/Terfenol‐D shows stronger ME coupling than that in PMN‐28PT/Terfenol‐D. At a thickness of 0.10–0.12 mm for the single crystal plate, a giant magnetoelectric coefficient (α_ME) up to 2 V/cm·Oe is obtained for PMN‐33PT/Terfenol‐D at a static magnetic field of 200 Oe and 1 kHz of the alternating magnetic field. In situ domain structure observations reveal the domain morphology change during the applied magnetic loadings. In PMN‐28PT, the domains are of predominantly rhombohedral (R) phase and they change into monoclinic M_A phase upon the magnetic loading via the strain transferred between Terfenol‐D plate and PMN‐PT single crystal. In PMN‐33PT, domains of orthorhombic (O), R, and monoclinic M_C coexist and phase transitions from O to M_C and further to R phase occur upon the magnetic loading. The undulation and diversity of the domain structure makes the domains more susceptible to the magnetic loading via strain transferred between Terfenol‐D plate and PMN‐PT single crystal, and consequently, a strong ME coupling in the composites.     

Structural origin of room temperature poling enhanced piezoelectricity in modified Pb(Mg1/3Nb2/3)O3‐30%PbTiO3 crystals

The piezoelectric properties of [110]‐oriented Mn‐doped Pb(Mg_1/3Nb_2/3)O₃‐30%PbTiO₃ single crystals was found to be enhanced by poling at room temperature, relative to traditional poling on field‐cooling (FC). High‐resolution x‐ray diffraction data revealed a phase transition sequence of cubic→tetragonal→ orthorhombic (O)→monoclinic B‐type (M_B) on field‐cooling with a phase coexistence of single domain O and M_B at 300 K in the FC state; whereas poling at room temperature revealed a M_B single phase. Accordingly, the structural origin of the piezoelectricity enhancement on poling at room temperature is attributed to a pure M_B phase. It is probable, in the FC state, that field‐cooling results in defect dipole migration, which then acts to stabilize regions of the O phase on cooling into the M_B one.     

Large piezoelectricity and potentially activated polarization reorientation around relaxor MPB in complex perovskite

Improving piezoelectric performance is always favorable to further enhance the sensitivity and accuracy of piezoelectric devices. Here, a complex piezoelectric system of Pb(Ni_1/3Nb_2/3)O₃-Pb(Yb_1/2Nb_1/2)O₃-Pb(Hf_0.1Ti_0.9)O₃ is designed and investigated in detail. Optimized piezoelectric response of ～ 880 pC/N is achieved at the composition of 0.51PNN-0.09PYN-0.40PHT. The characterization of TEM and In-situ high-energy synchrotron diffraction indicate that nanodomain growth and microdomain switching occurs in succession at around coercive electric field. Most interestingly, the coexisted tetragonal and rhombohedral-like phase transforms into multiple monoclinic-like phases with polarization vectors aligned as close to the electric field direction as possible under the strong electric field. The enhanced polarization instability in this complex morphotropic phase boundary sample should be ascribed to the strong local heterogeneity. The novel polarization rotation behavior found in this work would be important guidance for designing high-performance piezoceramics.     

Modified Pb(Mg1/3Nb2/3)O3-PbZrO3–PbTiO3 ceramics with high piezoelectricity and temperature stability

There is a great demand to develop ferroelectric ceramics with both high piezoelectric coefficient and broad temperature usage range for emerging electromechanical applications. Herein, a series of Sm³⁺-doped 0.25Pb(Mg_1/3Nb_2/3)O₃-(0.75−x)PbZrO₃-xPbTiO₃ ceramics were fabricated by solid-state reaction method. The phase structure, dielectric and piezoelectric properties were investigated, where the optimum piezoelectric coefficient d₃₃ = 745 pC/N and electromechanical coupling factor k₃₃ = 0.79 were obtained at the morphotropic phase boundary composition x = 0.39, with good Curie temperature T_C of 242°C. Of particular importance is that high-temperature stability of the piezoelectric and field-induced strain was obtained over the temperature range up to 230°C for the tetragonal compositions of x = 0.40. The underlying mechanism responsible for the high piezoelectricity and temperature stability is the synergistic contribution of the MPB and local structural heterogeneity, providing a good paradigm for the design of high-performance piezoelectric materials to meet the challenge of piezoelectric applications at elevated temperature.     

Fabrication and characterization of (Pb(Mg1/3Nb2/3)O3, Pb(Yb1/2Nb1/2)O3, PbTiO3) ternary system ceramics

New ternary compositions in the Pb(Mg_1/3Nb_2/3)O₃-Pb(Yb_1/2Nb_1/2)O₃–PbTiO₃ (PMN-PYbN-PT) system were prepared using 0.5Pb(Yb_1/2Nb_1/2)O₃-0.5PbTiO₃ (PYbNT) and (1-x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (x = 0.26; PMNT26 or x = 0.325; PMNT32.5) powders synthesized via the columbite method. Dense (≥ 96% of theoretical density) ceramics with PMN/PYbN mole ratios of 25/75 (R-25), 50/50 (R-50) and 75/25 (R-75T and R-75R) were fabricated by reactive sintering at 1000 °C for 4 h. Therefore, incorporation of PYbNT to PMNT successfully decreased sintering temperature of PMNT from 1200 °C-1250 °C to 1000 °C. Samples with higher density and perovskite ratio together with lower weight loss possessed higher dielectric and piezoelectric values in each composition. The R-75 samples had remanent polarization (P_r) values of 34-36 μC/cm² and piezoelectric charge coefficient (d₃₃) of 560 pC/N. The sharp phase transition PMNT as a function of temperature became broader or more diffuse with increasing PYbNT content. However, PYbNT addition to PMNT increased Curie temperature (T_c) from 183 °C (for PMNT32.5) to 220-242 °C (for R-75T and R-75R) to 336 °C (for R-25). Therefore, these ternary compositions can be tailored for various high temperature applications due to the relatively higher T_c with enhanced piezoelectric and dielectric properties as compared to PMNT.     

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.     

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.     

Tunability properties in the paraelectric state of the Pb(Mg1/3Nb2/3)O3 ceramics

Pb(Mg_1/3Nb_2/3)O₃ ceramics prepared via columbite method exhibit high crystallinity and high density after sintering at 1200 °C. Typical relaxor behavior are demonstrated by the dielectric data. Although showing a diffuse phase transition, at room temperature the system is in its paraelectric state, i.e. the PMN structure is fully cubic. The dc-tunability was investigated above the room temperature, when other field-induced contributions than ferroelectric polarization might cause non-linearity. A random non-interacting dipolar unit in a double well potential was employed to describe the ?(E) non-linearity. The temperature-dependence of the average polarization corresponding to the polar nanoregions in the paraelectric state of the PMN relaxor was calculated from the ?(E) data at various temperatures above T_m. A similar trend of decreasing as increasing temperature shows the spin-glass local order parameter determined from the dielectric constant data in the paraelectric state. The local order parameter in the paraelectric state is determined by the nanopolar domains size and correlations.     

Properties of Low‐Temperature Sintering PNN–PMW–PSN–PZT Piezoelectric Ceramics with Ba(Cu1/2W1/2)O3 Sintering Aids

Piezoelectric ceramics Pb(Ni_1/3Nb_2/3)O₃–Pb(Mg_1/2W_1/2)O₃–Pb(Sb_1/2Nb_1/2)O₃–Pb(Zr_0.39Ti_0.61)O₃ with Ba(Cu_1/2W_1/2)O₃ sintering aids were fabricated using economical industrial oxide powders and their piezoelectric, dielectric, and ferroelectric properties were investigated in order to develop low‐temperature sintering ceramics for multilayer piezoelectric actuators. A quadratic formula and the Curie–Weiss law reveal that the ceramics are typical displacive‐type ferroelectric relaxors. The ceramics sintered as low as 900°C have good piezoelectric properties of d₃₃ = 551 pC/N, k_p = 0.52, ε_r = 3583, tgδ = 0.02, and T_C = 161°C, which is much promising to manufacture multilayer piezoelectric transducers.     

Preparation and characterization of Pb(Lu1/2Nb1/2)O3–Pb(In1/2Nb1/2)O3–PbTiO3 ternary ferroelectric ceramics with high phase transition temperatures

To explore new relaxor‐PbTiO₃ systems for high‐power and high‐temperature electromechanical applications, a ternary ferroelectric ceramic system of Pb(Lu_1/2Nb_1/2)O₃–Pb(In_1/2Nb_1/2)O₃–PbTiO₃ (PLN–PIN–PT) have been investigated. The phase structure, dielectric, piezoelectric, and ferroelectric properties of the as‐prepared PLN–PIN–PT ceramics near the morphotropic phase boundary (MPB) were characterized. A high rhombohedral‐tetragonal phase transition temperature T_R‐T of 165°C and a high Curie temperature T_C of 345°C, together with a good piezoelectric coefficient d₃₃ of 420 pC/N, were obtained in 0.38PLN–0.20PIN–0.42PT ceramics. Furthermore, for (0.8?x)PLN–0.2PIN–xPT ceramics, the temperature‐dependent piezoelectric coefficients, coercive fields and electric‐field‐induced strains were further studied. At 175°C, their coercive fields were found to be above 9.5 kV/cm, which is higher than that of PMN–PT and soft P5H ceramics at room temperature, indicating PLN–PIN–PT ceramics to be one of the promising candidates in piezoelectric applications under high‐driven fields. The results presented here could benefit the development of relaxor‐PbTiO₃ with enhanced phase transition temperatures and coercive fields.     

Improved piezoelectricity of lead-based PNN-PIN-PT ternary ceramics via polymorphic nanodomain modulation

High-performance piezoelectric materials are widely used in electromechanical applications such as sensors, actuators, and transducers. Herein, improvement in electrical properties of Pb(Ni_1/3Nb_2/3)O₃−Pb(In_1/2Nb_1/2)O₃−PbTiO₃ relaxor ferroelectrics by modulating the polymorphism of nano-scale domain is reported, and piezoelectric coefficients d₃₃ and d₃₃* as high as 948 pC/N and 1108 pm/V, respectively, are achieved. The high piezoelectric response is elucidated by combining cryogenic dielectric, Rayleigh analysis, and scanning electron microscopy with piezoresponse force microscope. During the transition from the tetragonal to rhombohedral phase, the morphology of the ferroelectric domains changes significantly, mesoscopic domain destruction is observed, and thus nano-scale domains appear as an extrinsic contribution of piezoelectricity. In addition, nano-scale domains promote polarization rotation, thus, improving the piezoelectric response. The improved piezoelectric performance demonstrates good thermal stability, retaining the inverse piezoelectric coefficient of approximately 1000 pm/V near 70 °C. This work provides a good example of improving ceramics' piezoelectric response by modulating the polymorphism of nanoscale domains.     

Temperature and Frequency Dependence of Electric Field‐Induced Phase Transitions in PMN–0.32PT

Single crystal (1 ? x)Pb(Mg_1/3 Nb_2/3)O₃–xPbTiO₃ [PMN–xPT] (x = 0.32) is a relaxor‐ferroelectric material known to exhibit ‘giant’ piezoelectric behavior, with achievable strains in excess of 1% for samples of certain particular crystallographic orientations and chemical compositions close to the morphotropic phase boundary. In this study, we investigate the electric field‐induced structural phase transitions in single crystal PMN–0.32PT with time‐of‐flight neutron diffraction and macroscopic electrical polarization measurements, and show that both the frequency of the applied ac field and the temperature of the sample are critical factors in determining these phase transition fields.     

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%.     

Evolution of polar nano-regions under electric field around ferro-paraelectric transition temperature and its contribution to piezoelectric property in Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 crystal

As one of the most pronounced structural features, polar nano-regions (PNRs) is believed to have significant contribution to the outstanding piezoelectric property of relaxor-based ferroelectrics. However, direct experimental investigation on the connection between the PNRs behavior under electric field and piezoelectric responses is still insufficient. In this work, by the combined use of piezoresponse force microscopy, polarization light microscopy, and the electrical property measurements, we investigate the structure evolution from macro-domains to PNRs around ferro-paraelectric phase transition temperature (T_m, 140?°C) in Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ single crystal. Most importantly, based on the corresponding analysis of unipolar strain-electric-field (S-E) curves at different temperatures and the direct observation of electric-field-induced structure evolution at T_m, we intensively investigate the response of PNRs to electric field and its contribution to piezoelectric property. We conclude that, under electric field, the active PNRs around T_m first serve as polar seeds to induce macro-domains from the non-polar matrix, then promote the switching of macro-domains. The large-field strain coefficient d₃₃^* in these two processes can achieve maximum of about 5410?pm/V and 61710?pm/V at T_m, and gradually decreases at higher temperature with lower PNRs content.