Pb(Mg1/3Nb2/3)O3-xPbTiO3 Research Articles

Giant electro-optic response in transparent rhombohedral ferroelectric Sm-PIN-PMN-PT crystal based on domain engineering

The relaxor ferroelectric crystal Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), located near the morphotropic phase boundary (MPB), exhibits exceptionally high piezoelectric and electro-optic (EO) responses. Nevertheless, lower optical transparency and phase transition temperature of PMN-PT limit its optical applications. The ternary system Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) holds promise in addressing these challenges with a higher Curie temperature. Additionally, specific ferroelectric domain polarization techniques can eliminate domain scattering, substantially enhancing the transparency of the crystal. In this study, we explore the optical properties of Sm-doped PIN-PMN-PT. We achieve a 2R domain-engineered state by polarizing along the (110) direction of the crystal. The high transparency allows us to extract an effective EO coefficient of up to 431.5 pm/V from the Sm-PIN-PMN-PT crystal at the telecommunications wavelength. Second-harmonic generation (SHG) probing verified the domain-engineered state in Sm-PIN-PMN-PT. The temperature-dependent SHG reveals the ferroelectric phase transition process, laying the groundwork for studying the stability of the EO response. The Sm-PIN-PMN-PT crystal exhibits an exceptionally high EO coefficient, which is crucial for the development of enhanced EO devices with high integration and low driving voltages.

High second-order nonlinearity in single-domain tetragonal PMN-PT single crystal

Recently, Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals present tremendous potential in optical applications such as Q-switches and invisible robotic devices because they possess high electro-optic properties and perfect transparency simultaneously. However, due to the difficulties in testing and sample preparation, the nonlinear optical properties of PMN-PT single crystals have not been reported yet, which poses a bottleneck for exploring its nonlinear application. In this work, a large second-order nonlinear coefficient (d31 ∼ 77.9 pm V−1) of single domain PMN-0.39PT single crystal has been revealed, which is times times higher than the maximum nonlinear coefficient of commercial LiNbO3 single crystal (d33 = 25.4 pm V−1). The complete set of nonlinear coefficients of the sample has been determined by second harmonic generation microscopy. This work presents the promising nonlinear optical property in PMN-PT single crystals and opens a door for designing high-performance nonlinear optical devices.

Lattice match between coexisting cubic and tetragonal phases in PMN-PT at the phase transition

(1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) perovskite-like solid solutions are recognized for their outstanding electromechanical properties, which are of technological importance. However, some significant aspects of the crystal structures and domain assemblages in this system and the role of these characteristics in defining the functional performance of PMN-PT remain uncertain. Here, we used synchrotron x-ray diffraction to investigate the phase transition linking the paraelectric (cubic) and ferroelectric (tetragonal) phases in a single crystal of 0.65PMN-0.35PT. We analyzed the evolution of reciprocal-space maps across this transition. These maps were collected using small temperature step (1 K) and a high reciprocal-space resolution to reveal changes in the splitting of Bragg peaks caused by the formation of ferroelastic domains in the low-symmetry phase. Our results uncovered a two-phase state, cubic plus tetragonal phases, which exists over a narrow temperature range of only ≈4 K and exhibits a thermal hysteresis of ≈1.8 K. Remarkably, within this state, the lattice parameter of the cubic phase, aC, matches the orientational average of the lattice parameters for the tetragonal polymorph, 23aT+13cT. We discuss the implications of this matching, highlighting the possibility of it being realized by the formation of an assemblage of tetragonal twin domains separated from the cubic phase by a strain-free {110} boundary, as in the “adaptive phase” but without domain miniaturization.

Ferroelectric SrMnO3 Thin Film Grown on (110)‐Oriented PMN‐PT Substrate

Exploring the unique physical properties of oxide perovskites necessitates their growth on diverse single‐crystal substrates. The thin‐film growth of perovskite SrMnO3 (SMO) has been a particular focus of research due to its emerging room‐temperature multiferroicity. Herein, the epitaxial thin films of (110)‐oriented SMO are grown on the piezoelectric (110)‐oriented (1–x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN‐PT) substrate. The effects of the thickness and oxygen annealing on the crystal structure, stoichiometry, and ferroelectric properties of the SMO thin film are systematically investigated. The tensile strain produced by the lattice mismatch between the bulk SMO and the PMN‐PT substrate causes an expansion of the c‐lattice parallel to the in‐plane direction of the substrate. The films show larger a‐, b‐, and c‐lattice parameters than the bulk material, resulting in volume expansion of the unit cell. This lattice expansion is attributed to the generation of oxygen vacancies driven by the reduced formation energy caused by the high elastic strain. Piezoelectric force microscopy reveals that the SMO film contains domains with strain‐mediated in‐plane and vacancy‐mediated out‐of‐plane polarization. Furthermore, the piezoelectric response of the PMN‐PT substrate effectively modulates the biaxial tensile strain in the SMO film, offering a potential strategy for controlling the crystal structure and ferroelectric properties of SMO.

Potentials and Limits of PMN-PT and PIN-PMN-PT Single Crystals for Pyroelectric Energy Harvesting

Waste heat is inherent to industrial activities, IT services (e.g., data centers and microprocessors), human mobility, and many other common processes. The power lost each year in this way has been estimated in the 1000 TWh in the EU which, owing to skyrocketing energy prices and not least the urgent need for decarbonizing the economy, has engendered tremendous research efforts among scientists and engineers to recover/recycle this waste energy. Beyond established thermal engineering solutions for waste heat, advances in multifunctional materials open new paradigms for waste heat harvesting. Two smart material types are of particular focus and interest at present; these are thermoelectric and pyroelectric materials, which can both transform heat to electrical power, though via different effects. The present paper summarizes our research work on a new class of pyroelectric materials, namely <111> oriented (1-x)(Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT) and x-Pb(In1/2 Nb1/2)O3-y-Pb(Mg1/3 Nb2/3)O3-(1-x-y)-PbTiO3 (PIN-PMN-PT) single crystals that exhibit some of the highest pyroelectric properties ever measured. First, a figure of merit for pyroelectric energy harvesting is derived, followed by a detailed assessment of the properties of the said crystals and how they depend on structure, poling, thickness, and temperature. The properties are further contrasted with those of conventional pyroelectric crystals. It is concluded that the PMN-PT-base single crystals are best suited for harvesting devices with a working temperature range from 40 to 100 °C, which encompasses waste heat generated by data centers and some chemical and industrial processes, affording the highest figure of merit among pyroelectric materials.

Piezoelectric properties of thin-plate Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals for high-frequency transducer

Thickness dependence of the dielectric and piezoelectric properties of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals (x = 0.28, 0.29, and 0.30) grown using the modified Bridgman method was investigated. After annealing and repoling, the free dielectric constant of 7600 and the dielectric loss lower than 2.1% were obtained for 0.05 mm thick PMN-0.30PT, which are superior to previously reported properties for similar thicknesses. Although the free dielectric constant of PMN-0.28PT and PMN-0.29PT decreased by up to 10% as the sample thickness decreased from 0.30 to 0.05 mm, it improved after annealing and repoling, and remained stable at each thickness. From sample surface evaluations, a mechanically damaged layer was observed near the ground surface. This layer influences the crystal strain direction and crystal phases, suggesting that it influences the degradation properties.

Pure- and Pseudo-Lateral-Field-Excitation Characteristics of Relaxor Ferroelectric Single Crystal PMN-PT.

The relaxor ferroelectric single crystal (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) has high piezoelectric constants, and thus has a good application prospect in the field of highly sensitive piezoelectric sensors. In this paper, for relaxor ferroelectric single crystal PMN-PT, the bulk acoustic wave characteristics on pure- and pseudo-lateral-field-excitation (pure- and pseudo-LFE) modes are investigated. LFE piezoelectric coupling coefficients and acoustic wave phase velocities for PMN-PT crystals in different cuts and electric field directions are calculated. On this basis, the optimal cuts of pure-LFE and pseudo-LFE modes of relaxor ferroelectric single crystal PMN-PT are obtained, namely, (zxt)45° and (zxtl)90°/90°, respectively. Finally, finite element simulations are carried out to verify the cuts of pure-LFE and pseudo-LFE modes. The simulation results show that the PMN-PT acoustic wave devices in pure-LFE mode have good energy-trapping effects. For PMN-PT acoustic wave devices in pseudo-LFE mode, when the device is in air, no obvious energy-trapping emerges; when the water (as a virtual electrode) is added to the surface of the crystal plate, an obvious resonance peak and the energy-trapping effect appears. Therefore, the PMN-PT pure-LFE device is suitable for gas-phase detections. While the PMN-PT pseudo-LFE device is suitable for liquid-phase detections. The above results verify the correctness of the cuts of the two modes. The research results provide an important basis for the development of highly sensitive LFE piezoelectric sensors based on relaxor ferroelectric single crystal PMN-PT.

Ferroelectric Domain Wall Engineering Enables Thermal Modulation in PMN-PT Single Crystals.

Acting like thermal resistances, ferroelectric domain walls can be manipulated to realize dynamic modulation of thermal conductivity (k), which is essential for developing novel phononic circuits. Despite the interest, little attention has been paid to achieving room-temperature thermal modulation in bulk materials due to challenges in obtaining a high thermal conductivity switching ratio (khigh /klow ), particularly in commercially viable materials. Here, room-temperature thermal modulation in 2.5mm-thick Pb(Mg1/3 Nb2/3 )O3 -xPbTiO3 (PMN-xPT) single crystals is demonstrated. With the use of advanced poling conditions, assisted by the systematic study on composition and orientation dependence of PMN-xPT, a range of thermal conductivity switching ratios with a maximum of ≈1.27 is observed. Simultaneous measurements of piezoelectric coefficient (d33 ) to characterize the poling state, domain wall density using polarized light microscopy (PLM), and birefringence change using quantitative PLMreveal that compared to the unpoled state, the domain wall density at intermediate poling states (0< d33 <d33,max ) is lower due to the enlargement in domain size. At optimized poling conditions (d33,max ), the domain sizes show increased inhomogeneity that leads to enhancement in the domain wall density. This work highlights the potential of commercially available PMN-xPT single crystals among other relaxor-ferroelectrics for achieving temperature control in solid-state devices.

A phenomenological study on temperature-concentration-electric field phase diagram of relaxor ferroelectrics PMN-PT single crystals

The theoretical temperature-concentration-electric field (T-x-E) phase diagram of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) is investigated under the electric fields applied along the [001], [011] and [111] directions in the pseudo-cubic coordinate. Using the structurally stable tenth-order Landau–Ginzburg–Devonshire potential model, different two-dimensional sections of T-x-E phase diagram such as T-x (E[001] = E[101] = 0.1, 1kV/㎝) and E-T (x = 0.26, 0.28, 0.3, 0.32, 0.34, 0.36 and 0.38) phase diagrams, and T-x-E[001] one are constructed for PMN-PT single crystals. Also, based on the phenomenological results for T-x-E phase diagram, the features of symmetry changes from high symmetry phase, cubic one, to low symmetry phases, rhombohedral, tetragonal, orthorhombic, monoclinic and triclinic ones, possible during the phase transitions occurring at different temperatures, concentrations and electric fields in PMN-PT single crystals are predicted. The anomalies in dielectric and piezoelectric coefficients accompanied with the symmetry changes are studied. The topological features of T-x-E phase diagram of PMN-PT single crystals are qualitatively in good agreement with those of different piezo/ferroelectrics (BaTiO3, KNbO3, (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT)) in which the symmetry of order parameter is characterized by the image-group ImΓ4− = m3m of the irreducible representation Γ4− of the space group Pm3‾m as in PMN-PT single crystals.

Low-voltage magnetoelectric coupling in membrane heterostructures.

Strain-mediated magnetoelectric (ME) coupling in ferroelectric (FE)/ferromagnetic (FM) heterostructures offers a unique opportunity for both fundamental scientific research and low-power multifunctional devices. Relaxor-FEs, such as (1 − x)Pb(Mg1/3Nb2/3)O3-(x)PbTiO3 (PMN-xPT), are ideal FE layer candidates because of their giant piezoelectricity. However, thin films of PMN-PT suffer from substrate clamping, which substantially reduces piezoelectric in-plane strains. Here, we demonstrate low-voltage ME coupling in an all-thin-film heterostructure that uses the anisotropic strains induced by the (011) orientation of PMN-PT. We completely remove PMN-PT films from their substrate and couple with FM Ni overlayers to create membrane PMN-PT/Ni heterostructures showing 90° Ni magnetization rotation with 3 V PMN-PT bias, much less than the bulk PMN-PT ~100-V requirement. Scanning transmission electron microscopy and phase-field simulations clarify the membrane response. These results provide a crucial step toward understanding the microstructural behavior of PMN-PT thin films for use in piezo-driven ME heterostructures.

Ultratransparent PMN‐PT Electro‐Optic Ceramics and Its Application in Optical Communication

AbstractElectro‐optic (E‐O) materials are essential to modern information society, especially for optical switches, modulators, and filters in optical communication. In this paper, ultrahigh transparent (1−x)Pb(Mg1/3Nb2/3)O3‐xPbTiO3 (PMN‐PT) relaxor ferroelectric ceramics are fabricated. The effect of Sm‐doping content (0, 0.5, 1.0, 1.5, and 2.0 mol%) on PMN‐PT transparent ceramics is systematically investigated on the optical transparency, electro‐optic coefficient, extinction ratio, and half‐wave voltage. Results indicate that 0.5 mol% Sm‐doped PMN‐PT ceramic shows the optimal comprehensive performance, including high transparency of 69.6%, large quadratic E‐O coefficient of 35 × 10–16 m2 V−2, decent extinction ratio of 32 dB, and low half‐wave voltage (113 V at d = L = 1 mm). An electro‐optic modulator is designed based on the PMN‐PT transparent ceramics and its application in optical communication is realized, such as rapid information modulation, analog signal (audio frequency), and digital signal (graphic patterns) transmission. These results indicate that Sm‐doped PMN–xPT transparent ceramics are promising candidates for E‐O modulation applications.

Designed morphotropic relaxor boundary ceramic exhibiting large electrostrain and negligible hysteresis

Electromechanical materials with large electrostrain and low hysteresis are strongly desired for high-precision actuator applications. Despite extensive studies for more than half a century, it is still a challenge to obtain large electrostrain and low hysteresis simultaneously due to the so-called strain-hysteresis trade-off. Here, we report a mechanism to overcome this trade-off: a ceramic composition locating at a morphotropic relaxor boundary (MRB), exhibits enhanced electrostrain and reduced hysteresis as compared with off-MRB compositions. The MRB, a composition-induced boundary separating two relaxors with different local polar symmetries, is attained by transforming an morphotropic phase boundary (MPB) in Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) through doping lanthanum. The performances of large electrostrain of 0.227% and negligible hysteresis of 3% of MRB composition are the best, as evidenced by occupying a virgin region in the strain-hysteresis chart of relaxor electromechanical ceramics. Moreover, this MRB ceramic maintains the large electrostrain and low hysteresis over a temperature range from 35 to -35 °C. The understanding of abnormal effects of MRB is established through combining microstructure observations and Landau theory analysis: the MRB composition with morphotropic nanodomain structure and higher degree of local structural heterogeneity shows a flatter energy profile with much lower energy barrier, thereby leading to a large electrostrain and negligible hysteresis. Our work demonstrates that the MRB is an effective mechanism to design relaxor materials with large electrostrain and low hysteresis simultaneously. We predict that more high-performance MRB electromechanical materials will be found in properly doped MPB systems.

Temperature and Electric Field Dependent Phase Transformations in [001] PMN-PT Single Crystal

The capacitance of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) [001]-oriented single crystal was examined as a function of temperature and applied external dc electric field. The phase transition temperatures under the applied electric field were measured upon cooling the crystal (zero-field heating field-cooling condition) from paraelectric cubic phase. From these data, temperature versus electric field phase diagram of PMN-xPT crystal have been constructed and discussed.

Dynamic behaviors of ferroelectric domain structures in Eu-doped PMN-PT transparent ceramics studied by piezoresponse force microscopy

In this paper, we study ferroelectric domain structures, optical properties, as well as domain dynamic performances induced by external in-plane electric field of Eu-doped lead magnesium niobate-lead titanate [Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT)] transparent ceramics mainly via piezoresponse force microscopy (PFM). It is found that Eu doping play a significant role on the domain structures and domain switching behavior in PMN-PT transparent ferroelectrics. For some compositions the switching of domain structures exhibit a normal evolutionary trend, while for the compositions with low Eu doping content, unusual anisotropic polarization switching behaviors were obtained in macrodomain regions under in-plane bias in the Eu-doped PMN-PT transparent ceramics.

Enhanced dielectric and ferroelectric properties in lead magnesium niobate-lead titanate ferroelectrics solid solutions by controlling the sintering protocols

Due to requirements for miniaturization and integration of electronic devices, ferroelectric materials with high dielectric permittivity would have potential applications in dielectric capacitors. In this work, (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) powders with x from 0.10 to 0.30 were obtained on the basis of a transitional columbite precursor method, while sintering processes were carried out under three protocols, i.e., (I) 1230 °C for 2 h, (II) 1230 °C for 16 h and (III) 1250 °C for 2 h. The temperature-dependent dielectric properties measured from 25 °C to 225 °C show that, under protocols II and III, the maximum permittivity (εm) is significantly improved compared to those obtained via protocol I. A maximum εm of 47036 is obtained in x = 0.25 composition under protocol II, and the εm is increased by more than 90% at the same composition. In the ceramics sintered through protocols II and III, the characteristics of both dielectric relaxations and dielectric dispersions are also enhanced. In addition, the ferroelectric and piezoelectric properties also show a marked increase in the composition of x = 0.3. Our results suggest that the dielectric and ferroelectric properties of PMN-xPT solid solutions could be effectively enhanced by controlling the sintering protocols.

Optimizing the piezoelectric vibration of Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 single crystal by alternating current polarization for ultrasonic transducer

Alternate current poling (ACP) is an effective method to enhance the piezoelectric performance of Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals dramatically. For their application in piezoelectric transducers for medical imaging, the beam mode vibration of PMN-0.25PT single crystal resonators after ACP was investigated by combining experimental impedance measurements and finite element simulation. The complete material coefficients of PMN-0.25PT single crystals were obtained by using pulse-echo ultrasound and inverse impedance spectroscopy. Compared to traditional direct current poling (DCP), the beam mode electromechanical coupling coefficient (k33′) of PMN-0.25PT for ACP reaches up to 89.1% from 84.5% of DCP. As the attribution of the special periodic stripe domain structure (109° domain), the lateral vibration will be suppressed effectively in the array transducer. This indicates that AC-poled PMN-0.25PT single crystals can be an efficient strategy to obtain higher sensitivity and a larger bandwidth in ultrasonic transducers.

Phenomenological theory of phase transitions in the MPB region of (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals

ABSTRACTA higher-order Landau–Ginzburg–Devonshire theory is proposed to describe phenomenologically the complex phase transitions in the MPB region of the relaxor ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-PT) single crystals. Using the singularity theory, a structurally stable 10th-order potential with four varying expansion coefficients (a1, a11, a2 and a12) depending on temperature and composition is found out. By studying on two- and three-dimensional sections of a four-dimensional phase diagram a1-a11-a2-a12 in the space of phenomenological parameters, the range of coefficient parameters by which the structural stability of the potential model can be guaranteed is determined. The theoretical temperature-composition phase diagram is constructed and it is shown that this is in good agreement with both recent experimental data and first-principle calculation for the symmetry change. Moreover, temperature dependence of dielectric constants for various compositions is studied.

Scaling behavior of dynamic hysteresis of PMN‐PT relaxor ferroelectric ceramics near the morphotropic phase boundary

AbstractDue to the feature of domains, ferroelectric materials display hysteresis behavior with respect to the change of the applied electric field. Every ferroelectric material has its own unique hysteresis loop reflecting the information of domain reversal under an electric field. In this work, the scaling behaviors of dynamic hysteresis in relaxor (1‐x)Pb(Mg1/3Nb2/3)O3‐xPbTiO3 (PMN‐PT) ceramics with different compositions were studied systemically. Our results showed that the evolution of scaling behavior in PMN‐PT ceramics can be divided into three stages, which is independent of the phase structure of the ceramics and the testing electric field frequency. The relationship between hysteresis area &lt;A&gt; and field amplitude E0 obeys the power law &lt;A&gt;∝ in the low and high E0 regions, where the reorientations of 180° and non‐180° domain are dominant, respectively. However, the dynamic hysteresis area &lt;A&gt; does not follow the power law in the intermediate E0 regions, which is attributed to the interaction of different domain reversal mechanisms. Furthermore, the hysteresis area &lt;A&gt; decreases gradually with increasing frequency at a certain E0 and the time‐dependent domain reversal process was also discussed.

Achieve single domain state in (111)-oriented rhombohedral phase PMN-PT relaxor ferroelectric single crystals for electro-optical application

An electro-optic (EO) modulator is one of the most important optical devices and has been widely used in the photonic industry. Performance of EO modulators mainly depends on the property of EO materials. Here, the EO property of the (111)-oriented single domain rhombohedra phase (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystal is investigated. Due to the light scattering by domain walls, a single domain crystal is essential and has been well prepared here by a thermal annealing and high temperature poling process. It is found that domains become irregular with significantly decreased dimension after annealing, which indicates that the ferroelastic domain walls are eliminated. A crack-free single domain crystal shows excellent optical quality, with a high transmittance of approximately 70% in near-infrared regions. Finally, the effective EO coefficient of the (111)-oriented rhombohedral phase PMN-PT crystal is measured by a Senarmont compensator amplitude modulator. An effective EO coefficient of 112 pm/V is obtained in the (111)-oriented rhombohedral phase PMN-PT crystal, which is much higher than that of the commercial LiNbO3 crystal, indicating the potential for use in compact and low driving voltage EO devices.

Multi-layered domain morphology in relaxor single crystals with nano-patterned composite electrode

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystals, especially with compositions near its morphotropic phase boundary (MPB), have been employed for a broad range of applications such as ultrasound transducers, sensors, and actuators. To further enhance the properties of PMN-PT, electrode patterning, as a method of domain engineering, was proved to be an effective approach. In our previous report, a 200 nm grating pattern electrode (Ti/Au–MnOx) (nano-electrode) was prepared on one surface of PMN-PT crystal, exhibiting 30% d33 enhancement. In this work, the multi-layered domain morphology and the domain engineering from nano-electrode were characterized using piezoresponse force microscopy (PFM). A hypothetical domain engineering model for nano-electrodes is established to explain the experimental results as well as the property enhancement from the nano-electrode. The electrode patterning proves that the nano-scale modification can tune the macro-scale piezoelectric properties of the bulk material.