PMN-PT Ceramics Research Articles

Significantly enhanced transmittance and EO property in PMN-PT via optimized two-step pressure-free sintering

It is a great challenge to prepare Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) ceramics of very high transparency with only oxygen atmosphere pressureless sintering process. To address this issue, this work proposed an optimal low-cost two-step oxygen atmosphere sintering process with a first step at high temperature (T1) for minutes, followed by a second step at lower temperature (T2) for hours without applied pressure. High transmittance of 70 % in the near-infrared wavelength was achieved by our novel two-step process, which far exceeds the performance of PMN–PT ceramics prepared by only oxygen atmosphere sintering process reported in the past and demonstrates comparable performance compared to the costly hot-pressing sintering process. Meanwhile, it shows a high quadratic electro-optic (EO) coefficient of 42.1 × 10−16 m2 V−2, which is meaningful for applications in EO devices. Furthermore, the effect of the temperature difference between the first and second sintering step on the microstructure, transmittance, domain structure, ferroelectric and dielectric property, and polarization switching were discussed. The enhanced transparency is mainly attributed to the higher relative density, and weaker photoluminescence effect with lesser light absorption loss at optimal T1-T2. The improved EO property is due to greater polarization response originating from the interaction of defect dipoles and nanodomains. Such a process should facilitate the cost-effective preparation of other transparent electro-optic materials for practical applications.

Investigations on electric properties and domain structures of Nd-doped 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 relaxor ferroelectric ceramics with high piezoelectric properties

Although rare earth neodymium (Nd) doping is common in Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, it is rarely reported in PMN–PT ceramics. To explore the effect of Nd doping on PMN–PT ceramics, PMN–30PT:xNd3+ (x = 0%, 1%, 2%, and 3%) relaxor ferroelectric ceramics were fabricated using a solid-state method via two-step sintering. An enhanced piezoelectric charge coefficient (d33) of ~870 pC/N and a high piezoelectric strain coefficient (d33⁎) of ~1025 pm/V were achieved for x = 2%. Through Rayleigh analysis of polarization–electric field (P–E) hysteresis loops under small electric fields, it was found that the dielectric property was mainly influenced by the intrinsic contribution (local lattice distortion). Furthermore, by investigating domain configurations, high piezoelectric properties were found to be associated with the domain size reduction and local structural heterogeneity. The results indicate that the PMN–30PT:xNd3+ ceramics is a promising material for electronic devices, and that rare earth Nd doping is an efficient strategy for improving the electronic performance of Pb-based relaxor ferroelectrics.

Determining AC polarization conditions of ferroelectric materials by dynamic scaling method

Alternating current (AC) polarization can significantly improve electrical and optical performance of ferroelectrics, but there is still no theoretical guidance on how to get the best AC polarization conditions. In this paper, dynamic scaling method is firstly used to the determine optimal AC polarization process, and high piezoelectric coefficients were obtained at a low electric field and a very short time. Results indicate that it is effective not only for Pb-based PMN-PT ceramics, single crystal and PZT ceramics, but also for lead-free BNT-BT ceramics. The dynamic scaling method is expected to provide great support for AC polarization for ferroelectric materials.

Effect of Poling on Dielectric Properties of PMN-PT Ceramics

This article presents the phase transition analysis of PbMg1/3Nb2/3O3-PbTiO3 ceramics. The ceramics were prepared by a conventional solid-state reaction method in two steps. Structural analysis confirms the single phase formation without any impurity phases. Temperature dependent dielectric properties were measured on unpoled and poled ceramics. It is observed that poling process helps to identify diffuse phase transitions.

Domain structure and dielectric diffusion-relaxation characteristics of ternary Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ceramics

Relaxor-based ternary Pb([Formula: see text][Formula: see text])O3–Pb([Formula: see text][Formula: see text])O3–PbTiO3 (PIN–PMN–PT) single crystals and ceramics are promising candidates for high-performance electromechanical conversion devices. It is known that the domain structure and dielectric diffusion–relaxation characteristics are crucial to the excellent performances of relaxor ferroelectrics. In this work, we prepared the PIN–PMN–PT ceramics with various PIN/PMN proportions and systematically investigated their domain structure and dielectric diffusion–relaxation properties. The effect of PIN/PMN proportion on the domain size and dielectric diffusion–relaxation characteristics was also studied. The investigations showed that PIN–PMN–PT ceramics presented multi-type domain patterns comprising irregular island domains and regular lamellar domains. Moreover, the dependent relations of PIN/PMN proportions on the dielectric diffusion and domain size indicated that the PIN composition has a stronger lattice distortion than PMN composition; increasing the PIN proportion can enhance the dielectric diffusion and decrease the domain size. Our results could deepen the understanding of structure–property relationships of multicomponent relaxor ferroelectrics and guide the design and exploration of new high-performance ferroelectric materials.

Comparison of the performance characteristics of the tonpilz transducers fabricated from 0.60PMN-0.40PT & PZT piezoceramics

In this study, tonpilz transducers based on 0.60Pb(Mg1/3Nb2/3)O3-0.40PbTiO3 (60PMN-PT) and commercially available lead zirconate titanate (PZT) compositions (PZT 4, PZT 5H, PZT 8 and PZT 5A) were designed, fabricated, characterized and compared for their underwater performance. Each stack is composed of two rings of PZT or PMN-PT ceramics. Transducers were designed and analyzed using the commercial ATILA finite elements analysis (FEA) code. Commercially available powders were used for PZT, whereas 60PMN-PT powders with pure perovskite phase were synthesized using solid-state reaction route. Ceramic rings have been produced using dry pressing. Dielectric, piezoelectric and electromechanical properties of the rings were calculated using the resonance method. Vibration modes of the rings and transducers constructed from various types of piezoceramics were analyzed using FEA. The main resonance frequency of the tonpilz transducer belonging to the longitudinal piston mode was measured in the mid-frequency range between 30 and 35 kHz. Underwater acoustic measurements were conducted on polymer-coated transducers, and their performances were compared for possible underwater acoustic applications. Transducers fabricated from 60PMN-PT were found to have comparable underwater performance with that of PZT 4, where the Transmitting Voltage Response (TVR) reached 135 − 136 dB re 1 µPa/V @1 m range with a −3dB bandwidth of 4 kHz. These results indicated the viability of using 60PMN-PT ceramics in active device applications in an array form.

Improved piezoelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 textured ferroelectric ceramics via Sm-doping method

Sm-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Sm: PMN-PT) textured ceramics were fabricated by Template Grain Growth (TGG) using plate-like<001>oriented BaTiO3 (BT) as templates. The effects of PT and Sm contents on the crystal structure, microstructure, and piezoelectric, dielectric and ferroelectric properties of Sm: PMN-PT textured ceramics were investigated in details. Sm-doping was found to effectively improve the piezoelectric and dielectric properties of PMN-PT textured ceramics. For 1.9 mol% Sm: PMN-29PT textured ceramics with the Lotgering factor of 0.90, the piezoelectric coefficient d33 can reach up to 1040 pC/N. The relaxation behavior for Sm: PMN-29PT textured ceramics progressively increase with increasing Sm content. The room temperature dielectric constants of Sm: PMN-29PT textured ceramics continuously increase with increasing Sm contents and are not sensitive to increasing PT contents, while the temperature of the maximum dielectric constant continuously decreases with increasing Sm contents and increases with increasing PT contents. The saturation polarization and remnant polarization of Sm: PMN-29PT textured ceramics gradually decrease with increasing Sm content while the coercive field is not enlarged. This novel Sm: PMN-PT textured ceramics will further provide a new promising application prospect for ultrasonics, actuators, and transducers.

Local structural heterogeneity induced large flexoelectricity in Sm-doped PMN–PT ceramics

The recently discovered large flexoelectricity in relaxor ferroelectrics has rekindled considerable research interest. In this paper, several Sm-doped Pb(Mg2/3Nb1/3)O3–xPbTiO3 (PMN–xPT) ferroelectric ceramics were prepared and the relationship between flexoelectricity and PT content was systematically investigated. The largest flexoelectric response (∼550 μC/m) was observed in the Sm-doped PMN–32PT ceramic, which should be accounted for in the reorientation of the polar nanoregions. At room temperature, the flexoelectric response of Sm-doped PMN–32PT ceramic is an order of magnitude higher than that of the parent PMN–PT ceramics and even 50% higher than that of Bi–PMN–32PT ceramic (∼300 μC/m). Such a big increment is directly related to the greater local structural heterogeneity caused by Sm3+ ions into PMN–PT. Therefore, the result presented in this paper verifies that introducing local structural heterogeneity is a feasible approach to achieve ultrahigh flexoelectricity.

Flash Sintering Effect on PMN-PT Ceramics

Densification of PMN-PT piezoelectric ceramic powder is carried out by electric field assisted/flash sintering method. The composition selected in PMN-PT materials system is 0.67[Pb(Mg1/3Nb2/3)O3]−0.33(PbTiO3). During flash sintering experiment, 200 V/mm electric field is applied on sample with 0.1 amp current cutoff value. Flash sintering is accomplished in less than 90 sec at ~700 °C. Relative density for sintered sample is measured approximately 94 % which is reasonable value comparing with literature. SEM microstructure illustration exhibits proper consolidation morphology which is agreement with the relative density measurement. According to XRD analysis, the said materials system shows consistency in rhombohedral perovskite crystal structure and preserve its chemical and physical composition during whole experimental cycle. By electric field assisted/flash sintering technique, the sintering temperature is decreased from 1200 °C to 700 °C along with a decrement in sintering time from 2 hours to 90 seconds. PMN-PT is properly produced by flash sintering method for the first time with respect to open literature. Hence, this densification method will gain importance to reduce toxic Pb emission aroused at high temperature processes.

Fine-grained relaxor ferroelectric PMN-PT ceramics prepared using hot-press sintering method

Relaxor ferroelectric PbMg1/3Nb2/3O3-PbTiO3 (PMN-PT) ceramics are high-performance piezoelectric materials that are widely used in many electronic devices. However, it is extremely difficult to manufacture thin piezoelectric components dozens of micrometers in size using commercial coarse-grained PMN-PT ceramics. This limits the application of PMN-PT ceramics to high-frequency ultrasonic devices. In this work, we prepared a dense, fine-grained PMN-PT ceramic at low temperature using a hot-press sintering (HPS) method. The HPS ceramic had small grains with an average size of 1 μm and maintained high performance with a large permittivity (εr = 4500), piezoelectricity (d33 = 650 pC/N), and electrostrain (SE = 0.14% at 20 kV/cm). The large volume fraction of grain boundaries led to stronger relaxor behavior of the fine-grained PMN-PT ceramic than of the normal coarse-grained one. Owing to its small grains and high piezoelectric performance, this fine-grained PMN-PT ceramic meets the strict requirements of manufacturing thin piezoelectric components. Our results demonstrate that PMN-PT ceramics have great potential for developing low-cost, high-frequency ultrasonic devices by replacing expensive piezoelectric single crystals.

Ultrahigh-order mode-assisted hybrid optoelectronic bistability with an ultralow threshold.

A hybrid optoelectronic bistability is realized with the assistance of an ultrahigh-order mode (UHM) excited in a symmetrical metal-cladding waveguide (SMCW). PMN-PT ceramics is selected as the guiding layer, which possesses the voltage modulated refractive index and thickness by means of an electro-optical effect and converse-piezoelectric effect. An amplified voltage signal translated from the intensity of reflected light is exerted on the guiding layer, whose parameter variations can alter the resonance condition of the UHM and finally lead to a dramatic change in the intensity of the reflected light. Since the full width at half-maximum of the UHM is extremely narrow, a hysteresis behavior with a milliwatt threshold between the incident light and the reflected light can be achieved when a positive feedback is established. Our bistability configuration is simple and not limited to TM polarization.

Structural features and energy harvester device applications of textured 0.675 PMN–0.325 PT piezoceramics

In the current study, textured lead magnesium niobate–lead titanate solid solution with composition 0.675Pb(Mg1/3Nb2/3)O3–0.325PbTiO3 (0.675PMN–0.325PT) has been fabricated with 0.7 mol% manganese (Mn) doping to enhance the soft character and the figure of merit (FOM). Random and textured PMN–PT plates were prepared by tape casting where 1 vol% plate-like barium titanate (BaTiO3) single-crystal templates were added to induce texture. A detailed structural investigation using scanning/transmission electron microscopy (STEM) and precession electron diffraction techniques has been conducted to establish the orientational relationship between the PMN–PT matrix and the BT templates. The FOM of textured and doped PMN–PT was found to increase for almost fourfold compared to random undoped case. Characterization of the energy harvesting (EH) performance of unimorph EH devices indicated an over twofold increase in the output power of the doped and textured case in comparison to the undoped and random PMN–PT ceramics.

Atomic-scale origin of ultrahigh piezoelectricity in samarium-doped PMN-PT ceramics

Designing high-performance piezoelectric materials based on atomic-scale calculations is highly desired in recent years, following the understanding of the structure-property relationship of state-of-the-art piezoelectric materials. Previous mesoscale simulations showed that local structural heterogeneity plays an important role in the piezoelectric property of ferroelectrics; that is, larger structural heterogeneity leads to higher piezoelectricity. In this Rapid Communication, by combining first-principles calculations and experimental characterizations, we explored the atomic-scale origin of the high piezoelectricity for samarium-doped $\mathrm{Pb}(\mathrm{M}{\mathrm{g}}_{1/3}\mathrm{N}{\mathrm{b}}_{2/3}){\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{PbTi}{\mathrm{O}}_{3}$ (PMN-PT) ceramics, which possesses the highest piezoelectric ${d}_{33}$ of $\ensuremath{\sim}1500\phantom{\rule{0.16em}{0ex}}\mathrm{pC}\phantom{\rule{0.28em}{0ex}}{\mathrm{N}}^{\ensuremath{-}1}$ among all known piezoelectric ceramics. The impacts of various dopants on local structure and piezoelectric properties of PMN-PT ceramics were investigated in terms of the effective ionic radius and cation valence. Our results show that A-site dopants with a valence of 3+ are more effective to produce local structural heterogeneity in PMN-PT when compared with the A-site dopants with a valence of 2+, and a smaller dopant size leads to a larger variation of local structure. According to this study, the outstanding piezoelectricity in Sm-doped PMN-PT ceramics is attributed to the fact that $\mathrm{S}{\mathrm{m}}^{3+}$ is the smallest ions that can entirely go to the A site of PMN-PT rather than the B site. The present work may benefit the design of high-performance piezoelectric materials based on the concept of local structural engineering.

Temperature-insensitive large electrocaloric effect near room temperature in La3+-doped lead magnesium niobate-lead titanate ceramics

The influence of La3+-doping on the electrocaloric effect (ECE) of the 0.75(Pb1-3x/2Lax)(Mg1/3Nb2/3)O3-0.25(Pb1-3x/2Lax)TiO3 (L-PMN-PT: x/75/25 x = 0.0–4.0 mol.%) ceramics was studied. With the increase of La3+-doping in these ceramics, the relaxor ferroelectric properties increase, while the average grain size, coercive field Ec and Curie temperature TC decrease. As a result, a maximum adiabatic temperature change ΔT as high as 0.68 K, measured by direct measurement method, was achieved under a lower electric field (E) intensity of 5 kV/mm at 383 K for samples with x = 2.0 mol.%. Besides the high ΔT value, the La3+-doping also leads to a temperature insensitivity of ΔT. The variation of ΔT is less than 0.15 K, or 28.3%, over a wide temperature range of 303–423 K. The La3+-doped PMN-PT ceramics, with large and temperature insensitive ΔT over a broad temperature range, is very helpful for practical application. The reduction of Ec and TC can be attributed to the suppression of long-range coupling between oxygen octahedrons due to the partial replacement of Pb2+ by La3+. The temperature insensitivity of ECE is attributed to the enhancement of relaxor ferroelectric properties.

Large flexoelectric response in PMN-PT ceramics through composition design

Flexoelectricity yields electric polarization through graded strains and exists in various kinds of solid dielectrics but usually with a weak coupling response. In this letter, several Bi-doped Pb(Mg2/3Nb1/3)O3-xPbTiO3 (PMN-xPT) ferroelectric ceramics were prepared and the interplay of their piezoelectricity and flexoelectricity was systematically investigated. The largest flexoelectric response (∼300 μC/m) was 30 times larger than that of pure PMN-PT and was observed in the Bi-doped PMN-32PT, where the after poling piezoelectric coefficients were also the largest (990 pC/N) among all the compositions. This suggests that the apparent flexoelectricity in ferroelectrics is highly related to the bulk piezoelectricity. Therefore, introducing a local structural heterogeneity is considered as a feasible approach to achieve an ultrahigh piezoelectric response while also providing an ultrahigh flexoelectricity.

Y3+ doped 0.64PMN-0.36PT ceramic for energy scavenging applications: Excellent piezo-/ferro-response with the investigations of true-remanent polarization and resistive leakage

In this work, the detailed ferroelectric properties of pure and yttrium doped 0.64 Pb(Mg1/3Nb2/3)O3-0.36PbTiO3 (Y-doped PMN-PT) ceramics including determination of true remanent polarization and study of resistive leakage were investigated. In dielectric study, the transition temperature (Tm) for the pure and Y-doped ceramic was found to be 205 °C and 165 °C, respectively. Displacement vs. Voltage (D-V) butterfly loops were traced from which a high value of the piezoelectric coefficient for Y-doped PMN-PT (d33 = 604 pm/V) was revealed which was fairly greater than the observed value for pure PMN-PT (d33 = 547 pm/V). The Y-doped PMN-PT ceramic displayed excellent saturated ferroelectric hysteresis loops with higher values of coercive field (Ec), spontaneous (Ps) and remanent (Pr) polarizations, and pyroelectric coefficient (p) compared to the pure PMN-PT ceramic. Also, the Y-doped PMN-PT ceramic displayed good fatigue resistant characteristic indicating its high ferroelectric quality. The relative values of true remanent polarization i.e. Ptr/Pr (in %) were found to be ∼82.86% and 89.60% for pure and Y-doped PMN-PT, respectively using the “Remanent Hysteresis” Task. Also, the resistive-leakage characteristic of both pure and doped ceramics was analyzed using Time-dependent compensated (TDC) hysteresis task. Finally, both pure and Y-doped PMN-PT ceramics have been used for building piezoelectric energy harvesting devices (PEHDs). The Y-doped PMN-PT ceramic based PEHD showed enhanced performance by generating an output voltage around 60 V under periodic mechanical tapping (∼2.0 kgf @ 5 hz) and thus finds application in powering various self-powered devices.

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

AbstractThe doping of ZnO is efficient to improve the piezoelectric property and thermal stability of Pb(Mg1/3Nb2/3)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 &lt; 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 &gt; 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.

Estimation of energy density of PMN-PT ceramics utilizing mechanical stress

Present study introduces an indirect measurement of energy density of (1-x)Pb(Mg1/3Nb2/3)O3-(x)PbTiO3 (PMN-PT) ceramics under compressive stress and electric field. The method works analogous to Olsen cycle which is a demonstration of a novel cycle converting mechanical energy into electrical energy. A large amount of electro-mechanical energy conversion can be achieved via this method. The ceramics were investigated under 0–75 MPa and 1–15 kV/cm of applied mechanical stress and electric field, respectively. A maximum energy density of 68 kJ/m3/cycle was achieved in 0.7PMN-0.3PT ceramic. The obtained result is significantly greater than that of linear piezoelectric phenomena.

Effect of grain size on piezoelectric, ferroelectric and dielectric properties of PMN-PT ceramics

Grain size has significant effects on the electromechanical response of piezoceramics. Since the sintering temperature and holding duration affect the grain size and correspondingly their effective piezoelectric response, these issues should be appropriately addressed in order to properly design smart and intelligent systems. In this paper, PMN-PT piezoceramics with different grain sizes are synthesized by using conventional solid state processing and two-stage sintering method. Grain size effects on the hysteresis, fatigue and creep response are analyzed. Dielectric, ferroelectric and piezoelectric material properties of PMN-PT ceramics are investigated. The piezoelectric coefficient and remnant polarization exhibit diverse grain size effects depending on the sintering temperature and holding duration. The relative dielectric permittivity, piezoelectric coupling constant and dielectric constant show maximum values of 4104.2, 559 pC/N 562.291 pC/N and 0.705 for the microstructure with average grain size of 3.8 μm. The myriad effects of grain size on piezoelectric response are reported in details.

Enhanced Ferroelectric and Piezoelectric Properties of (1−x)PMN-xPT Ceramics Based on a Partial Oxalate Process

The pyrochlore phase in ferroelectric and piezoelectric materials is the main obstacle device application due to its poor electrical properties. Especially, the pyrochlore phase is frequently observed in the perovskite-based metal-oxide materials including piezoelectric and ferroelectric ceramics, which are based on solid-state reaction methods for fabrication. To overcome these problems, advanced innovative methods such as partial oxalate process will be investigated. In this method, crystalized magnesium niobite (MN) and lead titanate (PT) powders will be coated with a certain amount of lead oxalate and, then, the calcination process can be carried out to form the PMN-PT without pyrochlore phase. In this study, (1−x)PMN-xPT ceramics near the morphotropic phase boundary (MPB), with compositions of x = 0.25–0.40, have been prepared employing the partial oxalate method at various temperatures. The crystalline, microstructure, and piezoelectric properties of (1−x)PMN-xPT ceramics depending on the sintering temperature were intensively investigated and discussed. By optimizing the sintering temperature and compositions from the PMN-PT ceramics, the maximum value of the piezoelectric charge coefficient (d33) of 665pC/N, planar electromechanical coupling factor (kp) of 77.8%, dielectric constant (εr) of 3230, and remanent polarization (Pr) of 31.67 μC/cm2 were obtained.