O3 xPbTiO3 Research Articles

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.

Sm and Mn doped enhancing the electrical properties of .68PMN–.32PT relaxor ferroelectric thin films

Abstract(1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) has attracted attention due to its excellent electrical properties as a typical relaxor ferroelectric material. High‐quality Mn–Sm co‐doped 0.68PMN–0.32PT thin films were synthesized on the Pt/Ti/SiO2/Si substrates by sol–gel based on spin coating method. The results show that 1 mol% Mn–2 mol% Sm co‐doped PMN–PT thin films have high dielectric constant (εr ∼ 1895) and relatively low dielectric loss (tanδ ∼ .039) at 1 kHz. They also show superior ferroelectric polarization (Pmax ∼ 53.71 μC/cm2, Pr ∼ 30.85 μC/cm2) and high dielectric breakdown strength (∼1656.6 kV/cm), which are primarily due to the low leakage current density (∼10−7 A/cm2). This work suggests a practical approach to enhance the dielectricity, piezoelectricity, and ferroelectricity of PMN–PT thin films.

Optical Properties of PT‐Based Relaxor Ferroelectric Crystals

AbstractDuring the last two decades, PT‐based relaxor ferroelectric crystals such as (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 (PZN–PT), (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT), and (1−x−y)Pb(In1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–xPbTiO3 (PIN–PMN–PT or PIMNT) crystals, are widely studied due to their huge piezoelectric properties and super‐high electro‐mechanical coupling factors. They have excellent properties with compositions around the morphotropic phase boundary (MPB). It is gratifying that the PT‐based relaxor crystals are replacing traditional PZT piezo‐ceramics in many application fields. Most ferroelectrics with oxygen‐octahedral structure, which show outstanding electro‐mechanical properties, also have excellent optical performances. Ferroelectric single crystals with large electro‐optic (EO) modulation are widely applied in laser communication devices. For the practical applications, the knowledge of detailed optical parameters is desirable. This paper tries to show a global review on the optical properties of PT‐based relaxor ferroelectric crystals. In the present review, optical properties of the crystals are systematically summarized, including refractive index dispersion, transmittance, band gap, EO, acousto‐optic, and photorefractive properties. These properties change with the crystal composition, orientation, and poling condition. The purpose of the review is to provide a resource for the researchers who are concerned with basic physical investigation or optical device applications of the PT‐based relaxor ferroelectric crystals.

High radiation tolerance of electrocaloric (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3

High radiation tolerance of functional materials in harsh environments is the key requirement for the operation of particle accelerators, medical devices, nuclear power plants, satellites, and spacecraft. Neutron and gamma (γ) radiation can seriously affect the functional properties of the irradiated materials and thus the performance of the entire device. In this work, the feasibility of using (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–100xPT) electrocaloric materials in applications where the material is exposed to high neutron and γ-radiation is investigated. For this purpose, three different compositions of PMN–100xPT ceramics (x = 0, 0.1, and 0.35) were prepared and their dielectric, ferroelectric and electrocaloric properties were investigated before and after neutron and γ-irradiation. The samples were irradiated with a neutron fluence of 1015 to 1017 neutrons cm−2 with an energy of 1 MeV, which exceeds the largest expected neutron irradiation in the European Council for nuclear Research (CERN) and simultaneously exposed to γ-irradiation. The neutron and γ-radiation partially affect the functional properties of the PMN–35PT, the ceramic with distinct ferroelectric and weakened relaxor features, with some differences observed in the domain switching behavior, measured by conventional polarization versus electric field (P–E) hysteresis, at the highest radiation dose of 1017 neutrons cm−2. In contrast, the functional properties of the irradiated PMN and PMN–10PT samples with relaxor behavior are quite similar to those of the pristine samples, therefore, we conclude that these materials can be used as working materials in EC coolers exposed to such harsh environments.

Synthesis, structural evolution, and dielectric properties of a new perovskite solid solution (Pb0.5Sr0.5)(Zr0.5Ti0.5)O3–PbTiO3

AbstractTo explore lead‐reduced dielectric materials in the SrTiO3–PbTiO3–PbZrO3 ternary system, a novel solid solution between relaxor ferroelectric (Pb0.5Sr0.5)(Zr0.5Ti0.5)O3 and ferroelectric PbTiO3, namely (1 − x)(Pb0.5Sr0.5) (Zr0.5Ti0.5)O3–xPbTiO3 (lead–strontium–zirconate–titanate [PSZT]–PT), has been synthesized in the perovskite structure by high‐temperature solid‐state reaction method in the form of ceramics. The crystal structure and phase symmetry of the materials synthesized were analyzed and resolved based on X‐ray powder diffraction (XRD) data through both the Pawley and Rietveld refinements. The results of the structural refinements indicate that at low PT‐concentration end of the solid solution system, for example, x = 0.05, the PSZT–PT solid solution exhibits a cubic structural symmetry (with the space group Pm‐3m). As the PT concentration (x) increases, the structure of (1 − x)PSZT–xPT gradually transforms from the cubic to a tetragonal (P4mm) phase. In the composition range of x = 0.10–0.25, a mixture of the cubic and tetragonal phases was identified. As the concentration of PT increases, the proportion of the tetragonal phase increases at the expense of the cubic phase. For a composition of x > 0.25, a pure tetragonal phase is observed. The dielectric properties of the materials were studied by measuring the permittivity as a function of temperature at various frequencies. For the composition of x = 0.05, the temperature dependence of dielectric constant shows typical relaxor behavior. For x = 0.35, the dielectric peaks indicate a normal ferroelectric phase transition. Overall, a structural transformation from a central‐symmetric, nonpolar cubic phase to a non‐centrosymmetric, polar tetragonal phase is induced by the substitution of PT for PSZT in the pseudo‐binary solid solution of (1 − x)PSZT–xPT, which also reveals an interesting relaxor to ferroelectric crossover phenomenon.

Design and investigate the electrical properties of Pb(Mg0.2Zn0.2Nb0.2Ta0.2W0.2)O3–PbTiO3 high-entropy ferroelectric ceramics

High-entropy perovskite oxides with ferroelectricity have not been reported so far because these oxides have highly symmetric cubic structures. In this study, we propose a strategy of introducing morphotropic phase boundaries to obtain ferroelectricity in high-entropy perovskite oxides. We demonstrate the feasibility of the concept using (1−x)Pb(Mg0.2Zn0.2Nb0.2Ta0.2W0.2)O3–xPbTiO3 as a model system. It is anticipated that this concept can be applied to design and prepare various high-entropy ferroelectric and piezoelectric perovskite oxides.

Morphotropic phase boundaries of (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 probed by Raman spectroscopy at high temperature

Morphotropic phase boundaries (MPBs) in relaxor Pb(Zn1/3Nb2/3)O3–ferroelectric PbTiO3 systems were investigated by means of angle-resolved polarized Raman spectroscopy at 800 K in the paraelectric phase. The features of the spectra represented by contour maps were extracted through the multivariate curve resolution (MCR) method, rendering the comparison among the data with six compositions more accurate and convenient. The result indicates that the structure becomes unstable at x = 0.07, which is slightly smaller than the MPB occurring at x = 0.09. The additional analysis using the MCR method to investigate the x dependence of the extracted Raman spectra shows anomalies at the MPB. The information related to the MPB near room temperature could be extracted through Raman spectroscopy even in a simple high-temperature paraelectric phase.

Effects of poling on the electrical and electromechanical response of PMN–PT relaxor ferroelectric ceramics

The dielectric and piezoelectric response of the Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) polycrystalline ceramics after different poling procedures is examined and explained with respect to the phase composition and the domain structure. In the monoclinic (M) compositions a twice lower AC poling field is needed for a similar piezoelectric coefficient (d33) relative to DC poling. The high efficiency of AC poling of the M phase is assigned to its unique structure with low-angle nanodomain walls that are highly responsive to external fields and move in a ‘cascade-like’ motion, contributing to strains up to 0.5%. While the highest d33 is achieved at the morphotropic phase boundary (MPB), the dielectric permittivity of all room-temperature poled samples reached its peak on the tetragonal side of the MPB. The latter is assigned to the broadening of the MPB when poling above the inclined MPB, which can thus be manipulated by the proper poling conditions.

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.

Connecting the Multiscale Structure with Macroscopic Response of Relaxor Ferroelectrics

AbstractLead‐based relaxor ferroelectrics are characterized by outstanding piezoelectric and dielectric properties, making them useful in a wide range of applications. Despite the numerous models proposed to describe the relation between their nanoscale polar structure and the large properties, the multiple contributions to these properties are not yet revealed. Here, by combining atomistic and mesoscopic‐scale structural analyses with macroscopic piezoelectric and dielectric measurements across the (100–x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT) phase diagram, a direct link is established between the multiscale structure and the large nonlinear macroscopic response observed in the monoclinic PMN‐xPT compositions. The approach reveals a previously unrecognized softening effect, which is common to Pb‐based relaxor ferroelectrics and arises from the displacements of low‐angle nanodomain walls, facilitated by the nanoscale polar character and lattice strain disorder. This comprehensive comparative study points to the multiple, distinct mechanisms that are responsible for the large piezoelectric response in relaxor ferroelectrics.

Depolarization field in relaxor-based ferroelectric single crystals under one-cycle bipolar pulse drive**Project supported by the National Natural Science Foundation of China (Grant No. 11674270), the Fundamental Research Funds for Xiamen University, China (Grant No. 20720180113), the Education and Scientific Research Project for Young and Middle-aged Teachers of Fujian Province, China (Grant No. JAT170036), the Opening Fund of Acoustics Science and

The [001]c-polarized (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN−PT) single crystals are widely used in ultrasonic detection transducers and underwater acoustic sensors. However, the relatively small coercive field (∼ 2 kV/cm) of such crystals restricts their application at high frequencies because the driving field will exceed the coercive field. The depolarization field can be considerably larger in an antiparallel direction than in a parallel direction with respect to polarization when the bipolar driving cycle starts. Thus, if the direction of the sine wave signal in the first half cycle is opposite to the polarization direction, then the depolarized domains can be repolarized in the second half of the sine cycle. However, if the direction of the sine wave signal in the first half of the cycle is along the polarization direction, then the change is negligible, and the domains switched in the second half of the sine cycle cannot be recovered. The design of electric driving method needs to allow the use of a large applied field to emit strong enough signals and produce good images. This phenomenon combined with the coercive field increases with the driving frequency, thereby making the PMN−PT single crystals usable for high-frequency applications. As such, the applied field can be considerably larger than the conventionally defined coercive field.

Alternate current poling and direct current poling for Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

We have investigated the effects of alternate current poling (ACP) for four different plates of [100]-oriented (100 – x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT, x = 28, 29, 30, 31) single crystals (SCs) obtained from one ingot. A record high piezoelectric coefficient d33 of 3000 pC N–1 for PMN–30PT SCs, and a high free dielectric permittivity of 8900 for PMN–28PT SCs by ACP, 27% higher than those of conventional direct current poling (DCP), were confirmed. X-ray analysis revealed a higher (004) peak intensity and angle of ACP SCs compared to those of DCP. We assume that ACP creates a monoclinic multiphase (MB and MC) and eliminates some portion of the tetragonal phase in SCs. In addition, (004) peak shifts were different between the different PT composition SC samples. This work demonstrates an ACP process with excellent cost performance can offer promising prospects and practical value for PMN–xPT SC piezoelectric transducers.

Multi‐scale domain structure observation and piezoelectric responses for [001]‐oriented PMN‐33PT single crystal

AbstractMultiple phase coexistence contributes to the extraordinary piezoelectric behavior of (1‐x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT) near the morphotropic phase boundaries (MPBs). By incorporating an optical path of crossed polarized light (PLM) into the commercialized Piezoelectric Force Microscope (PFM) (named as PLM‐PFM system), in situ domain structure observation from micro‐ to nanoscale, as well as measurement of the piezoelectric behavior for individual domains can be realized. For [001]‐oriented single crystal of 67Pb(Mg1/3Nb2/3)O3‐33PbTiO3 (PMN‐33PT), fine domain boundary structures of rhombohedral (R), tetragonal (T), and monoclinic (M) phases are revealed. Measurements of the electric field‐induced displacement as a function of the applied DC electric field (VDC) are performed for domains with different polarization vectors. Values for the electric field‐induced displacement are in descending order for c‐domains of the M, R, and T phases. For an individual phase of T or M, the displacement increases when the angle between the polarization vector and the applied electric field decreases. The multi‐scale perspective of the domain structures and the corresponding piezoelectric response helps in understanding the ultra‐high piezoelectric performance for PMN‐PT single crystals near MPB.

Pyroelectric sensor based on Pb(Mg1/3Nb2/3)1-xTixO3 single crystals for solid state hydrogen storage reactors

The pyroelectric effect is commonly used to construct infrared radiation detectors. To pay attention to the possibility of using this phenomenon in materials based on relaxor-ferroelectric such as Pb(Mg1/3Nb2/3)1-xTixO3 (lead titanium-lead magnesium niobate), single crystals from solid solution were grown using modified Bridgman method with x taken three different range (x = 0.25, 0.33 and 0.40).In this work the operation principles for pyroelectric sensor and their properties are presented, with a brief review on the temperature stability of the Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT) single crystals. It was shown that the pyroelectric and dielectric properties are strongly dependent on composition (PT content), as well as the temperature variation. The investigations have revealed that the best choice for pyroelectric performances is <111>oriented PMN–0.25 PT, although, the PMN–0.33 PT and PMN–0.40 PT owns much better temperature stability, and higher Curie temperature Tc.The PMN–xPT single crystals showed promising pyroelectric performances, they can be used as thermal sensors and may be associated with temperature management systems to improve the performance of solid state hydrogen reactors.

Linear optical properties and second-harmonic generation of (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 single crystals

Transmission spectrum and refractive index of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-xPT) single crystals were studied and second-harmonic generation signal of the crystal powder was measured in order to characterize the nonlinear optical properties of the crystals. The poling procedure led to increase in the optical transmittance in visible spectral region. PMN-xPT single crystals were optically negative and the refractive index increased with PT concentration. Moreover, PMN-xPT crystals proved to have high nonlinear optical properties and the second-harmonic generation signal measured in powder of PMN-0.39PT crystal was greater than that of KH2PO4, KTiOPO4, and LiNbO3.

Synthesis and band-gap tuning of (Co, Bi) doped PbTiO3 for photoferroelectrics applications

In this study, We demonstrate the development of 0.40Bi (CoyTi1-y)O3–0.60PbTiO3 (BCT-60PT) ferroelectric samples using the conventional solid-state reaction technique . Phase identification and structural characterization of BCT-60PT powders were made by X-Ray diffraction technique. Significant effect of Co concentration on the structural and optical properties of the BCT-60PT has been observed. We have investigated the variation of the band gap with calcination temperature. The band gap tuning is done by varying the doping percentage of Co (y = 0.45, 0.5, 0.55, 0.60) in 0.40Bi (CoyTi1-y) O3–0.60PbTiO3. The optical band gap is found to reduce from 2.84 eV to 1.65 eV as the Co concentration increases in BCT-60PT. The reduced band gap makes the (1 -x)Bi(Co1/2Ti1/2)O3–xPbTiO3 promising multiferroic material for photoferrovoltaics applications.

Numerical modelling and experimental validation of a regenerative electrocaloric cooler

This paper reports on the research and development of a cooling device with an active electrocaloric regenerator (AER) based on the bulk ceramic material (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-100xPT). For the purposes of the study a 2D transient numerical model of the AER was developed. This model makes it possible to investigate the cooling characteristics of a device with an AER while considering the effect of the hysteresis of the electrocaloric material and the effect of the electric-energy recovery related to the polarization/depolarization process. The results of the numerical analyses show that the degree of electric energy recovery has a major impact on the efficiency of the device. By considering an idealised system for electric-energy recovery the energy efficiency (expressed by the coefficient of performance) of the device could be increased by up to ten times. A validation of the numerical model was performed through the design, construction and experiments on an improved AER cooling device. The results revealed a maximum specific cooling power of 16 W kg−1 and a maximum temperature span of 3.1 K for the new device.

Fabrication of PMN-PT/Epoxy 2–2 Composite Ultrasonic Transducers and Analysis Based on Equivalent Circuit Model

Single-crystal (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT) has great potential for use in ultrasonic applications; however, it is challenging to achieve both broad bandwidth and high sensitivity owing to the mismatch in acoustic impedance between the piezoelectric materials and loading medium. Fabrication of a matching layer for transducers is challenging owing to the increase in the center frequency of the transducer. In this study, a 2–2 PMN-PT-crystal composite was designed and fabricated, exhibiting desirable piezoelectric properties and lower acoustic impedance compared with single-crystal PMN-PT. Transducers based on the 2–2 PMN-PT composite were fabricated and analyzed in detail to investigate their sensitivity and bandwidth. Moreover, the effects of a backing layer on the transducer were investigated. The measured results showed that the bandwidth improved from 21.28% to 35.54% at the cost of reduced sensitivity of the transducer. Systematic analysis of this phenomenon using an equivalent circuit based on the Mason model is presented.

Electrophysical Properties of the PMN⁻PT⁻PS Solid Solution.

The (1 − y) ((1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3)–yPbSnO3 solid solution (PMN–PT–PS) was obtained and investigated in the present paper. For the analysis of the influence of the PbSnO3 component on the electrophysical parameters, the compositions from the rhombohedral phase, tetragonal phase, and a mixture of these phases were selected. The six compositions of the PMN–PT have been obtained using sol–gel methods (for values of x equal to 0.25, 0.28, 0.31, 0.34, 0.37, and 0.40). The ceramic samples of the 0.9(PMN–PT)–0.1(PS) solid solution have been obtained using the conventional ceramic route. X-ray diffraction (XRD), energy dispersive spectrometry (EDS), and microstructure measurements were performed, as well as tests regarding the dielectric, ferroelectric, piezoelectric properties and electric conductivity of the PMN–PT–PS ceramic samples versus temperature. Results of the measurements show that the obtained PMN–PT–PS materials have good electrophysical properties and are well suited for use in micromechatronic and microelectronic applications.