Ferroelectric Phase Transition Research Articles

Abnormal mechanism of infrared fluorescence intensities in multiple phase transitions of Li+/Er3+:BaTiO3 ferroelectric ceramics

A photoluminescence (PL) method to characterize phase transition processes of Li+/Er3+:BaTiO3 (BLET) ferroelectric ceramics by infrared fluorescence intensities has been proposed. The fluorescence intensities are applied to detect the phase transition of BLET ceramics in multiple phase transition regions. It proves that the change in fluorescence intensities at the phase transition is due to a variation in the radiative transition probability of the 4I13/2 level. A physical mechanism is elucidated considering the relationship between fluorescence properties and the phase structure. Our research benefits an in-depth understanding of the relationship between the PL characteristics and the phase structure of ferroelectric materials and further develops the application potential of PL methods in ferroelectric phase transition detection.

Photocarrier-induced persistent structural polarization in soft-lattice lead halide perovskites.

The success of the lead halide perovskites in diverse optoelectronics has motivated considerable interest in their fundamental photocarrier dynamics. Here we report the discovery of photocarrier-induced persistent structural polarization and local ferroelectricity in lead halide perovskites. Photoconductance studies of thin-film single-crystal CsPbBr3 at 10 K reveal long-lasting persistent photoconductance with an ultralong photocarrier lifetime beyond 106 s. X-ray diffraction studies reveal that photocarrier-induced structural polarization is present up to a critical freezing temperature. Photocapacitance studies at cryogenic temperatures further demonstrate a systematic local phase transition from linear dielectric to paraelectric and relaxor ferroelectric under increasing illumination. Our theoretical investigations highlight the critical role of photocarrier-phonon coupling and large polaron formation in driving the local relaxor ferroelectric phase transition. Our findings show that this photocarrier-induced persistent structural polarization enables the formation of ferroelectric nanodomains at low temperature, which suppress carrier recombination and offer the possibility of exploring intriguing carrier-phonon interplay and the rich polaron photophysics.

Catalytic Activity of BaTiO3 Nanoparticles for Wastewater Treatment: Piezo- or Sono-Driven?

Piezocatalytic reactions are generally excited by ultrasonication and, as such, should occur simultaneously with other catalytic reactions caused by different mechanisms such as sonocatalysis or tribocatalysis. One of the main challenges is how to discriminate between these effects in a catalysis experiment and quantify each contribution. In order to distinguish these effects, we use nano- and micro-particles of piezoelectric barium titanate (BaTiO3) and then compare their catalytic properties below and close to the piezoelectric to non-piezoelectric phase transition temperature at which the crystalline structure changes from the low-temperature tetragonal, piezoelectric phase to the higher-temperature cubic, non-piezoelectric phase. All other parameters, such as particle size, surface termination, etc., remain unaltered. The phase transition in bulk occurs at about 120 °C, but the transition temperature decreases as a function of particle size and reaches room temperature for particle sizes of about 20 nm. Transmission electron microscopy and X-ray diffraction were used to characterize the morphology and crystalline phase of the nanoparticles, respectively. Since the piezoelectric properties and the lattice dynamics are closely related, temperature-dependent Raman spectroscopy provides an even better insight into the nano- and micro-structural properties, allowing the ferroelectric phase transition temperature to be estimated. The catalytic activities of the BaTiO3 nanoparticles were determined by monitoring the optical absorption of a solution containing the model pollutant methyl orange, after ultrasonication of the solution to which were added the dispersed piezoelectric BaTiO3 particles as catalysts. An exponential-like correlation has been found between the catalytic reaction rates and the tetragonal distortion of the crystal structure of the BaTiO3 particles. Our study has also established that while 10% of the catalytic reaction of BaTiO3 is related to either sonocatalysis or tribocatalysis, the remaining 90% of the overall catalytic activity is ascribed to the piezocatalytic contribution.

Publisher's Note: “Unveiling the strain and structural ferroelectric phase transition induced by temperature in lead titanate perovskite modified with 40% of calcium” [J. Appl. Phys. 132, 244101 (2022)

Publisher's Note: “Unveiling the strain and structural ferroelectric phase transition induced by temperature in lead titanate perovskite modified with 40% of calcium” [J. Appl. Phys. 132, 244101 (2022)

Observation of dielectric resonance and negative capacitance in 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 textured thin films

Negative capacitance effect (NCE) in ferroelectric/dielectric thin film heterostructures has received a great deal of interest as it promises to bring down the operational voltage of field-effect transistors below the Boltzmann limit. Here, it has been observed in 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT)/SrRuO3 heterostructures grown on Pt/Ti/SiO2/Si substrate using pulsed laser deposition (PLD) technique. Phase pure PMN-PT thin film with (111) preferred orientation displayed excellent ferroelectric and dielectric properties with PS ∼36.80 μC/cm2, ϵr ∼1900 and tanδ ∼0.06 (at 1 kHz). Interestingly, dielectric resonance was realized around 3 MHz and fitted to Lorentz model. Its temperature variation beyond the ferroelectric phase transition showed clear signature of NCE after resonance frequency. Furthermore, the entire structure exhibited Fano-like resonance. The direct observation of NCE in relaxor ferroelectric, PMN-PT integrated on Si will aid in better understanding of the fundamental aspects of NCE which can trigger another technological revolution in semiconductor industry.

History dependence of avalanche dynamics of ferroelectric phase transition in BaTiO3 under external bias field

A ferroelectric phase transition under an external bias electric field after field cooling and zero field cooling in barium titanate single crystals shows scale invariant nucleation and growth of complex domain structures. The avalanche energy exponents vary with the external bias, depending on the cooling history of the sample under applied field or zero field cooling. After field cooling, resulting in a single domain sample, the energy exponent is near the integrated mean field value of 5/3, namely, 1.68 ± 0.022. The sample after field cooling shows the same exponent with an external bias electric field range of up to 4.5 kV/cm. The exponent of a multi-domain sample, after zero field cooling, decreases from ε = 1.85 to the fixed point of 1.66 under high fields. The different behavior is attributed to the greater complexity of domain patterns in the multi-domain sample, which reduces to a single domain state under strong applied fields. Compared with the single-domain state, the multi-domain state has more domain boundaries and the intersections formed by these domain boundaries. These domain boundaries and their intersections will hinder the movement of the phase boundary and act as a pinning effect on the front of the phase interface. The effect is to generate more small energy signals, making the critical exponent high. At the same time, the aftershock time distribution (Omori law) remains the same for all switching conditions with an Omori exponent near −1 and switching time correlations of −1 ± 0.05 for short times (<1 s) and −2 ± 0.10 for long times (>1 s).

Can the ferroelectric soft mode trigger an antiferromagnetic phase transition?

Type-II multiferroics, where spin interactions induce a ferroelectric polarization, are interesting for new device functionalities due to large magnetoelectric coupling. We report on a new type of multiferroicity in the quadruple-perovskite BiMn3Cr4O12, where an antiferromagnetic phase is induced by the structural change at the ferroelectric phase transition. The displacive nature of the ferroelectric phase transition at 125 K, with a crossover to an order-disorder mechanism, is evidenced by a polar soft phonon in the THz range and a central mode. Dielectric and pyroelectric studies show that the ferroelectric critical temperature corresponds to the previously reported Néel temperature of the Cr3+ spins. An increase in ferroelectric polarization is observed below 48 K, coinciding with the Néel temperature of the Mn3+ spins. This increase in polarization is attributed to an enhanced magnetoelectric coupling, as no change in the crystal symmetry below 48 K is detected from infrared and Raman spectra.

Potassium–Sodium Ceramics Modified with Metal Oxide Additives: Synthesis, Microstructure, and Properties

Single phase ceramic samples of new compounds (1 − x)(K0.5Na0.5)NbO3−xLa(Ag0.5Sb0.5)O3 (x = 0–0.15), modified by metal oxide additives ZnO, CuO, and MnO2, are prepared via a solid state reaction. The crystal structure, microstructure, and dielectric and ferroelectric properties of the samples are studied. It is established that a phase with a perovskite structure and an orthorhombic unit cell formed in each sample. Ferroelectric phase transitions are confirmed via dielectric spectroscopy. Generation of the second harmonic is observed, along with a drop in the temperature of transitions from the ferroelectric orthorhombic phase to the ferroelectric tetragonal phase, and then to the cubic paraelectric phase.

Three-dimensional porous borocarbonitride composed of pentagonal motifs as a high-performance pyroelectric material.

Pyroelectric materials have been attracting significant attention due to their intrinsic and permanent polarization, where the induced polarization is not associated with specific conditions, such as ferroelectric phase transition, strain gradient, dopants, and electric field. Thus, these materials have great potential for wide applications in energy conversion. Here, we propose a new 3D porous borocarbonitride termed PH-BCN, which is composed of pentagonal motifs with intrinsic polarization along the [0001] direction. Based on first-principles calculations, we show that PH-BCN possesses a record high longitudinal electromechanical coupling coefficient with the value of k33 = 97.99%, a remarkably strong SHG response (χ(2)xzx(0) = χ(2)yzy(0) = χ(2)zxx(0) = χ(2)zyy(0) = -6.23 pm V-1 and χ(2)zzz(0) = 21.21 pm V-1), and a record high shift current value of 908.58 μA V-2 due to the intrinsic vertical polarization. This study expands the family of pentagon-based materials, and may open a new frontier in the design of high-performance pyroelectric materials as well.

Superspace approach helps: determination of proton dynamics in the phase transition of modulated supramolecular ferroelectrics: 5,5′-dimethyl-2,2′-bipyridine and bromanilic acid

For the first time, the superspace approach describes the relation between four ferroelectric-paraelectric phases, by using a unique superspace group and analyzing intermolecular interactions in terms of t-plots. The proton dynamic has a dominant role in phase transitions.

Electron transport, ferroelectric, piezoelectric and optical properties of two-dimensional In2Te3: a first-principles study.

Two-dimensional (2D) materials have garnered significant interest in the fields of optoelectronics and electronics due to their unique and diverse properties. In this work, the electron transport, ferroelectric, piezoelectric, and optical properties of 2D In2Te3 were systematically investigated using first-principles based on density functional theory. The analysis of the phonon spectrum and elastic modulus of the Born effective criterion indicates that the structure of the novel 2D In2Te3 is dynamically stable. The calculation results show that 2D In2Te3 exhibits a carrier mobility as high as 3680.99 cm2 V-1 s-1 (y direction), a high in-plane polarization of 2.428 × 10-10 C m-1, and an excellent ferroelectric phase transition barrier (52.847 meV) and piezoelectric properties (e11 = 1.52 × 10-10 C m-1). The higher carrier mobility is attributed to the band degeneracy and small carrier effective mass. In addition, biaxial strain is an effective way to modulate the band gap and optical properties of 2D In2Te3. These properties indicate that 2D In2Te3 is a promising candidate material for flexible electronic devices and ferroelectric photovoltaic devices.

Superior Energy and Power Density Realized in Pb(Hf 1- x Ti x )O 3 System at Low Electric Field

The development of antiferroelectric materials with large energy density and fast discharge speed makes dielectric capacitors possess great prospects for applications in pulsed power technology. Here, the PbHfO 3 -based ceramics with compositions of Pb(Hf 1- x Ti x )O 3 (PHT, 0.01 ≤ x ≤ 0.05) were synthesized, and their antiferroelectricity and phase transition behavior were studied. According to the tests of x-ray diffraction, dielectric spectrum, and polarization–electric field hysteresis loops, PHT ceramics gradually transition from an orthorhombic symmetric antiferroelectric phase to a hexagonal symmetric ferroelectric phase at room temperature as Ti 4+ concentration increases. The forward phase switching field of antiferroelectric to ferroelectric phase transition can be markedly regulated by the introduction of Ti 4+ , and the optimal energy storage performance was obtained in Pb(Hf 0.98 Ti 0.02 )O 3 ceramics with a large recoverable energy storage density of W rec ~ 4.15 J/cm 3 and efficiency of η ~ 65.3% only at a low electric field of 190 kV/cm. Furthermore, the outstanding charge–discharge properties with an ultrafast discharge time (71 ns), remarkable discharged energy density (2.84 J/cm 3 ), impressive current density (1,190 A/cm 2 ), and ultrahigh power density (101 MW/cm 3 ) at a low electric field of 170 kV/cm were obtained in studied ceramics. The excellent energy storage performance of PHT ceramics provides a promising platform for the application of dielectric capacitors.

Процессы переключения в керамике твердых растворов на основе Ca-=SUB=-0.3-=/SUB=-Ba-=SUB=-0.7-=/SUB=-Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-

In this work, ceramic samples with a structure of the type of tetragonal tungsten bronzes, composition Са0.3Ba0.7Nb2O6 (CBN30) pure and with modifying additives SrTiO3, KTaO3 or LiTaO3 (5 mass %) were studied by the oscillographic method. It is shown that the introduction of modifying additives into CBN30 ceramics leads to an increase in the reversal polarization and to a decrease in dielectric losses, both at room temperature and at high temperatures. The introduction of LiTaO3 impurity into the CBN30 composition leads to the greatest increase in the reversal polarization. In contrast to ceramics based on lead zirconate titanate, which have a perovskite type structure, the introduction of SrTiO3 into CBN30 (having the structure of tetragonal tungsten bronzes) does not significantly improve the ferroelectric properties. It has been found that at temperatures above 100 °C for pure CBN30 ceramics, above 165 °C for CBN30 + 5% SrTiO3 and CBN30 + 5% KTaO3, and above 200 оС for CBN30 + 5% LiTaO3, there is a strong increase in dielectric losses. The contribution of dielectric losses to switching processes makes it impossible to determine the temperature of the ferroelectric phase transition for solid solutions based on CBN30 from the temperature dependences of dielectric hysteresis loops.

Local Probing ErCrO3

Local distortions in perovskite-like orthochromites are of extreme importance for the properties they exhibit. Here, we present the results of structural and DC magnetisation measurements combined with local probe studies in polycrystalline ErCrO3. The electric field gradient (EFG) parameters’ evolution with temperature shows two clear signals of local environment changes, one at the ferroelectric phase transition (TFE) and the other below 250 K. At the claimed TFE, the EFG changed from a slightly distorted axial symmetric to an EFG with axial symmetry (evidence that the local point-symmetry of the crystal might have changed). At a temperature around 250 K, we observed the development of a magnetic hyperfine field (MHF) and a change in the EFG to an axial slightly distorted one. These observations are rather in line with our magnetisation measurements, as a relatively strong coercive field was observed well above the Cr sub-lattice ordering temperature.

Элекрофизические свойства керамических твёрдых растворов Li0,03Na0,97TayNb1–yO3 со структурой перовскита, принадлежащих морфотропным областям

The temperature dependences of the complex permittivity and the dielectric loss tangent of ferroelectric solid solutions Li0.03Na0.97TayNb1–yO3 (y = 0.1–0.7) with the perovskite structure have been studied. It has been found that Li0.03Na0.97TayNb1–yO3 solid solutions undergo three phase transitions in the studied temperature range. The temperatures of ferroelectric phase transitions have been determined, and it has been established that an increase in the tantalum concentration leads to a decrease in this temperature. It is revealed that the studied solid solutions at room temperature have high values of εʹ in the low frequency region.

Unveiling the strain and structural ferroelectric phase transition induced by temperature in lead titanate perovskite modified with 40% of calcium

Structurally correlated ferroelectric phase transitions induced by temperature are reported for the solid solution Pb0.6Ca0.4TiO3 compound. Such phase transitions were analyzed by considering different parameters, such as lattice parameters, microstrain, dielectric properties, and thermal analysis. Synchrotron x-ray diffraction and Rietveld refinement studies revealed a tetragonal symmetry from room temperature up to ∼550 K and uniaxial microstrain from room temperature to ∼400 K. The first thermally driven phase transition observed was from displacive ferroelectric tetragonal symmetry to another non-displacive tetragonal symmetry. The next phase transition was from the tetragonal to cubic. The electric permittivity as a function of temperature for frequency from 1 kHz to 1 MHz and the differential scanning calorimetry report features typical of ferroelectric–paraelectric phase transition only around 400 K, and no other abrupt change in properties is observed at 550 K, indicating the sequence of first- and then second-order phase transition.

Abstracts

In this article, the effect of Zr addition on the crystalline structure, ferroelectric and piezoelectric properties of Barium Strontium Titanate (BST) ceramic have been studied. Zr was doped in the range of 0 ≤ x ≤ 0.20 in Ba0.90Sr0.10Ti1-xZrxO3 (BSZT) and it was prepared via solid state reaction technique. From the characterization studies, it was realized that Zr addition in BSZT ceramics results in slight modification of BSZT lattice, but due to diffusion of Zr into the lattice, the crystallite size as well as the microstructure of combined BSZT system got modified drastically. Zr addition in BSZT ceramics results in increase of lattice parameter due to larger ionic radius of Zr ions compared to Ti ions. Reduction of grain and crystallite size was also observed, which affects the ferroelectric behaviour of BSZT ceramic by influencing the polarization contribution from individual domains. This causes a slow transformation of sharp paraelectric-ferroelectric transition to diffusive ferroelectric phase transition and it also introduces relaxation phenomenon in the system at higher Zr compostion, which convert it to a relaxor ferroelectric. At relaxor phase a decreased spontaneous polarization and slimmer P–E hysteresis loop was observed with increasing Zr content. The main reason behind this conversion and modification in microstructural properties is because of the presence of strain in BSZT lattice which is due to replacement of Zr4+ (0.72 Å) inplace of smaller Ti4+ (0.609 Å) in more than a tolerable limit. Substitution of Zr4+ for Ti4+ in BaSrTiO3 introduces structural disorder, causing perturbations like local electric and strain fields. These perturbations reduce the long-range polar order resulting in relaxor behavior.

Effect of Zr substitution on electrical properties of Ba0.90Sr0.10Ti1−xZrxO3 (0 ≤ x ≤ 0.20) ceramics

In this article, the effect of Zr addition on the crystalline structure, ferroelectric and piezoelectric properties of Barium Strontium Titanate (BST) ceramic have been studied. Zr was doped in the range of 0 ≤ x ≤ 0.20 in Ba0.90Sr0.10Ti1-xZrxO3 (BSZT) and it was prepared via solid state reaction technique. From the characterization studies, it was realized that Zr addition in BSZT ceramics results in slight modification of BSZT lattice, but due to diffusion of Zr into the lattice, the crystallite size as well as the microstructure of combined BSZT system got modified drastically. Zr addition in BSZT ceramics results in increase of lattice parameter due to larger ionic radius of Zr ions compared to Ti ions. Reduction of grain and crystallite size was also observed, which affects the ferroelectric behaviour of BSZT ceramic by influencing the polarization contribution from individual domains. This causes a slow transformation of sharp paraelectric-ferroelectric transition to diffusive ferroelectric phase transition and it also introduces relaxation phenomenon in the system at higher Zr compostion, which convert it to a relaxor ferroelectric. At relaxor phase a decreased spontaneous polarization and slimmer P–E hysteresis loop was observed with increasing Zr content. The main reason behind this conversion and modification in microstructural properties is because of the presence of strain in BSZT lattice which is due to replacement of Zr4+ (0.72 Å) inplace of smaller Ti4+ (0.609 Å) in more than a tolerable limit. Substitution of Zr4+ for Ti4+ in BaSrTiO3 introduces structural disorder, causing perturbations like local electric and strain fields. These perturbations reduce the long-range polar order resulting in relaxor behavior.

Dynamical mean-field study of a photon-mediated ferroelectric phase transition

The interplay of light and matter gives rise to intriguing cooperative effects in quantum many-body systems. This is even true in thermal equilibrium, where the electromagnetic field can hybridize with collective modes of matter, and virtual photons can induce interactions in the solid. Here, we show how these light-mediated interactions can be treated using the dynamical mean-field theory formalism. We consider a minimal model of a two-dimensional material that couples to a surface plasmon polariton mode of a metal-dielectric interface. Within the mean-field approximation, the system exhibits a ferroelectric phase transition that is unaffected by the light-matter coupling. Bosonic dynamical mean-field theory provides a more accurate description and reveals that the photon-mediated interactions enhance the ferroelectric order and stabilize the ferroelectric phase.

Modeling polar order in compressively strained SrTiO3

Strontium titanate is an incipient ferroelectric in which superconductivity emerges at exceptionally low doping levels. Remarkably, stabilizing the polar phase through strain or chemical substitution has been shown to significantly enhance the superconducting critical temperature, and the polar instability plays a pivotal role in the majority of proposed superconducting pairing mechanisms. A rigorous understanding of ferroelectricity is therefore essential to elucidate the electron pairing mechanism in this material. To investigate the nature of the polar order in strontium titanate, we develop a simplified free energy model that only includes the degrees of freedom necessary to capture the relevant physics in a biaxially compressively strained system. Our model is able to calculate the energies of large, disordered systems with near DFT-level accuracy. We simulate the ferroelectric and antiferrodistortive phase transitions using the Monte Carlo method and discuss the coupling between various order parameters. Finally, we assess the character of the polar transition, which we find to be neither strictly displacive nor order-disorder.