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Recently, significant interest has been shown in using ferroelectric or piezoelectric energy harvesting to collect mechanical energy from the surrounding atmosphere to power next-generation wearable electronic sensors and devices. Due to their pyroelectric and piezoelectric capabilities and high permittivity for energy storage, ferroelectrics are a significant class of electroactive materials. As a result of its low price and high usability, piezoelectric energy harvesters have seen rapid development over the last decade. When used as part of a larger energy harvesting strategy, ferroelectric/ferroelastic switching may significantly boost energy density. Hence, this study suggests the Stable Diffusion Model-based Composite Layered Ferroelectric Ceramic Materials (SDM-CLFCM) for effective energy harvesting under the background of Meta-Universe. The highest output current and peak power density shown by the composite layered porous piezoelectric composite energy harvester are much greater than those reported for existing porous piezoelectric materials. [ABSTRACT FROM AUTHOR]

The author pays attention to the preparation and research of nanofiber membrane, which is a kind of indoor environment purification material, and has obtained a Electrospinning process that can produce nanofiber membrane materials with excellent performance through experiments. By adjusting the spinning solution, solvent, voltage, speed and other conditions, various structures of polylactic acid (PLA) fibers were prepared. The fiber was characterized by Scanning electron microscope and Transmission electron microscopy, and its filtration efficiency and filtration life were tested. The experimental results indicate that, the optimal spinning process is: voltage 20 kV, internal needle injection speed 2.0 mL/h, external needle injection speed 8.0 mL/h, temperature 25 °C, humidity 50%, receiving distance 20 cm, receiving substrate and covering layer made of polypropylene non-woven fabric, covering weight 2.0 g/m2, and filtering efficiency up to 99.47%. The characterization and testing results were analyzed, proving the ideal preparation process. [ABSTRACT FROM AUTHOR]

In the present study, particular aspects of the large-signal switching properties and electromechanical hysteresis of the lead zirconate titanate (PZT)-type porous piezoceramics were studied in comparison with the dense piezoceramics of the same composition. Large-signal ferroelectric polarization and strain hysteresis loops were recorded at the bipolar electric fields in the range of 0 ÷ 5 kV/mm and in the frequency range of 0.01 ÷ 5 Hz. Measurements and analysis were performed by means of the electromechanical measurement system (STEPHV) and electromechanical response characterization program (STEP), combining large-signal modeling of the mechanical and electrical behavior of ferroelectric materials. [ABSTRACT FROM AUTHOR]

The substitution of fossil energy for green-energy sources is a world demand. Photovoltaic devices are a well-known safety solution to convert solar energy into electricity. Ferroelectric materials are one of the most promising candidates for substituting Si-based compounds in solar-energy conversion devices due to their relatively low cost and bulk photovoltaic effect instead of the classical p-n junction. In this work, (K,Ba)(Nb,Ni)O3 single crystal was grown by vertical Bridgman-Stockbarger method, and structural, chemical, and optical properties of the as-grown material were characterized. Growth parameters were chosen based on the thermal properties of the precursor oxide and on theoretical models. [ABSTRACT FROM AUTHOR]

A comprehensive investigation has been conducted on Ba(2-x)Sr(x)GdFeNb4O15 powders. These powders were synthesized through the conventional solid-state reaction. X-ray diffraction analysis at room temperature has demonstrated that the samples adopt the TTB-structure, exhibiting the space-group P4/mbm. The Raman spectra of the samples exhibit remarkable similarity, yet distinct bands at different wave numbers, indicative of the varying modes of the MO6 octahedra. The dielectric studies have uncovered intriguing findings, including a high dielectric constant and a broad permittivity peak. Remarkably, the Curie temperature varies with the substitution rate, yet remains frequency-independent, a clear indication of these materials' classical ferroelectric behavior. [ABSTRACT FROM AUTHOR]

Today, great emphasis is placed on the creation of lead-free compounds that may be used in multi-functional equipment. This report describes the synthesis (through the solid-state technique) and physical characteristics (structural, electrical, and ferroelectric) of a polycrystalline Sr3Bi2WO9 compound (SBWO). A monoclinic crystal structure with cell parameters; a = 9.0285 Å, b = 16.6457 Å, c = 5.6787 Å with β = 93.13° is studied by analysis of X-ray diffraction method (crystallite size 100.77 nm). The purity, morphology, and elementary composition of elements were studied by SEM (grain size 0.582 μm) and EDX. The temperature-frequency variation of εr, tan δ, and σac were investigated. The drop in grain resistance value with increasing temperature demonstrates the NTCR property of the compound. It has been reported that the conduction process of the compound is based on a study of the modulus spectrum. SBWO is a possible choice for devices because it exhibits outstanding temperature-independent εr characteristics and reduced tanδ. Ferroelectric properties of the material (Ec=0.2655 kV/cm, Pr=0.00454 μC/cm2, Emax=2.478 kV/cm, and Pmax=0.0367 μC/cm2) shown by the electric field-dependent polarization at 25 °C. [ABSTRACT FROM AUTHOR]

Today, great emphasis is placed on the creation of lead-free compounds that may be used in multi-functional equipment. This report describes the synthesis (through the solid-state technique) and physical characteristics (structural, electrical, and ferroelectric) of a polycrystalline Sr3Bi2WO9 compound (SBWO). A monoclinic crystal structure with cell parameters; a = 9.0285 Å, b = 16.6457 Å, c = 5.6787 Å with β = 93.13° is studied by analysis of X-ray diffraction method (crystallite size 100.77 nm). The purity, morphology, and elementary composition of elements were studied by SEM (grain size 0.582 μm) and EDX. The temperature-frequency variation of εr, tan δ, and σac were investigated. The drop in grain resistance value with increasing temperature demonstrates the NTCR property of the compound. It has been reported that the conduction process of the compound is based on a study of the modulus spectrum. SBWO is a possible choice for devices because it exhibits outstanding temperature-independent εr characteristics and reduced tanδ. Ferroelectric properties of the material (Ec=0.2655 kV/cm, Pr=0.00454 μC/cm2, Emax=2.478 kV/cm, and Pmax=0.0367 μC/cm2) shown by the electric field-dependent polarization at 25 °C. [ABSTRACT FROM AUTHOR]

The Nd and Ti doped bismuth ferrite compound (Bi0.85Nd0.15)(Fe0.5Ti0.5)O3 has been synthesized through a solid state reaction method. Its various properties, such as structural, dielectric and ferroelectric features were thoroughly investigated. The XRD analysis confirms the phase formation with monoclinic symmetry of the compound. The field effect scanning electron microscope (FE-SEM) micrograph/image shows the surface morphology and uniformly distributed grains over its surface. Energy dispersive X-ray (EDX) suggests the presence of all ingredients with appropriate purity (constituent elements are in well ratios of their atomic and weight percentage). Investigation of impedance and dielectric data was carried out in an extensive range of temperature and frequency. Prepared material data expose a significant improvement in the electrical and dielectric characteristics. Frequency dependent ac-conductivity diagram/plot of present material obeys Jonscher's universal power law. The PE loop tracer study confirms the ferroelectric nature of the material. Present study offers several interesting features of the material for further device applications. [ABSTRACT FROM AUTHOR]

Ferroelectric materials are getting great interest due to their large applications in modern electronics technology such as memory devices, pyroelectric detectors, modulators, and so on, rubidium dihydrogen phosphate (RDP) is a member of Potassium dihydrogen phosphate family of ferroelectric crystals. In De Gennes–Kobayashi pseudospin model few extra terms like phonon anharmonic terms, extra spin phonon interaction terms, four body interaction terms and electric field terms are included. Dielectric properties have been investigated. Statistical Green function method of Zubarev is employed to derive excitation frequency, capacittivity, and dissipation factor for RDP. Theoretical data are compared to experimental data of other workers for RDP. [ABSTRACT FROM AUTHOR]

The Nd and Ti doped bismuth ferrite compound (Bi0.85Nd0.15)(Fe0.5Ti0.5)O3 has been synthesized through a solid state reaction method. Its various properties, such as structural, dielectric and ferroelectric features were thoroughly investigated. The XRD analysis confirms the phase formation with monoclinic symmetry of the compound. The field effect scanning electron microscope (FE-SEM) micrograph/image shows the surface morphology and uniformly distributed grains over its surface. Energy dispersive X-ray (EDX) suggests the presence of all ingredients with appropriate purity (constituent elements are in well ratios of their atomic and weight percentage). Investigation of impedance and dielectric data was carried out in an extensive range of temperature and frequency. Prepared material data expose a significant improvement in the electrical and dielectric characteristics. Frequency dependent ac-conductivity diagram/plot of present material obeys Jonscher's universal power law. The PE loop tracer study confirms the ferroelectric nature of the material. Present study offers several interesting features of the material for further device applications. [ABSTRACT FROM AUTHOR]

In the present study Al/a-Si:H/SiO2/n-Si/Al based bottom gate thin film transistor (BGTFT) was fabricated using remote plasma enhanced chemical vapor deposited (RPCVD) SiO2 and PECVD a-Si:H. The Al/a-Si:H/SiO2/n-Si/Al based bottom gate thin film transistor was studied with an intension to apply it for bio-sensing application. The transfer characteristics of BGTFT were studied. The values of Gdd are 3.14 × 10−7 S, 1.38 × 10−7 S, 3.34 × 10−8 S, 4.84 × 10−9 S & 1.57 × 10−10 S for gate voltage Vg = −2, −1, 0, 1 & 2 V respectively. The Gdd values are found to decrease with the increase of gate voltage (Vg). The values of Gdg are 5.36 × 10−8 S, 5.98 × 10−9 S, 7.28 × 10−7 S, 2.40 × 10−7 & 5.00 × 10−9 respectively for Vd = −2, −1, 0, 1 & 2 V. The present current level and the conductance of BGTFT is so large that it is not possible to detect the proteins and antibody as these bio-molecules have charge of the order of nano amps. Therefore it requires a needed focus to study the ferroelectric or high k material as the active material instead of a-Si:H for BGTFT for bio-sensing application as the ferroelectric materials have low conductance and channel current. This will be our future work to use ferroelectric or high k materials as the active materials of BGTFT. [ABSTRACT FROM AUTHOR]

Ferroelectric materials have been studied over the last three decades due to their exceptional physical properties, which make them promissory for several applications, such as pyroelectric sensors, nonvolatile memories, electro-optical devices, capacitors, etc. Among them, lead titanate (PbTiO3, PT), which has a tetragonal (P4mm) perovskite structure, has been considered a promising material for infrared detector applications (in both thin films and ceramic forms) and, therefore, it has been up today under the interest of many researches from the scientific community. In fact, recent advances in the synthesis methods for obtaining PT-based materials have promoted very interesting and intriguing phenomena in their micro(structural) properties, which still remains not fully understood. In this context, this work aims the investigation of the structural properties of PbTiO3 thin films, studied through X-ray diffraction and Raman spectroscopy techniques. In particular, the influence of the synthesis parameters, such as pyrolysis temperature, has been considered. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes is a new ferroelectric material exhibiting large piezoelectric properties and has desirable attention in biosensors and the healthcare field. A set of wearable belt was developed using PVDF films of 28 μm as sensitive element and conductive silver as the electrodes. The equipment was designed such that it can sense vibration which could be compatible to those produced by human sleep signal (SS) in a noninvasive way. The prototype of the wearable belt which has 1 × 24 parallel curved slender beams (CSBs) as sensing element using 28 μm thickness PVDF film was fabricated. The element is an assembly of layered media. The base of the sensitive element is a hyperelastic inferior arc polyhedron, on which a PVDF film with silver electrode patches, two 5 μm copper-clad signal interfaces attached to both sides of the PVDF film using conductive adhesive, and a protective surface layer of polyester film for insulation are stacked in sequence. The role of the polyhedron, copper surface end and parallel CSBs design to enhance detection signals, and the capability of the sensor to faithfully detect the SS were experimentally evaluated. Results showed that the new wearable belt (WB) has been manufactured to sense the SS including heartbeat rate (HR), respiration rate (RR) as well as postural signal (PS), and its sensitivity to external mechanical force or vibration is 1.5 times higher than that of a sheet sensitive structure device. All these experimental set-up proposed and developed by us showed the remarkable contribution of the sensitivity and repeatability (98.6%) in SS monitoring depending on signal characteristics such as frequency and amplitude. [ABSTRACT FROM AUTHOR]

Tuning the photoluminescence (PL) properties of lanthanide ions not only provides a deeper understanding of the luminescence mechanism, but also promotes its potential applications in lighting industry, volumetric 3 D display, biological assaying, and medical imaging. The traditional chemical strategies, such as changing the types or concentration of doped ions, changing the composition of host materials, changing the preparation process, etc, can easily adjust the photo excitation, energy transfer and emission processes, which have been widely employed. In spite of the strong ability to tune luminescence intensity and wavelength, these chemical methods are irreversible, which is difficult to observe the dynamic luminescence process and unfavorable for real applications. Recently, enabling in-situ, real-time and reversibly control PL response by the application of electric field has been realized through doping lanthanide ions into ferroelectric host materials. Herein, the electric field control of PL response in lanthanide doped ferroelectric bulks and thin films is summarized. The intrinsic luminescence mechanism under electric field and possible application directions in the future are discussed. [ABSTRACT FROM AUTHOR]

The electrocaloric effect (ECE) of Tin Titanate (SnTiO3) has been investigated in the present manuscript. A phenomenological model has been adopted for predicting electric polarization variation with temperature to examine electrocaloric properties such as entropy change, heat capacity change and relative cooling power. The results indicate the potential of this ferroelectric compound to achieve the ECE near Curie temperature (TC). It is useful as prospective candidate for cooling system in a wide temperature interval. The maximum change in entropy near TC obtained by phenomenological model has been compared with the value procured by Tarnaoui et al. [1]. The results confirm that the phenomenological model is undoubtedly beneficial for the prediction of the electrocaloric effect of ferroelectric materials. [ABSTRACT FROM AUTHOR]

The electrocaloric effect (ECE) of Tin Titanate (SnTiO3) has been investigated in the present manuscript. A phenomenological model has been adopted for predicting electric polarization variation with temperature to examine electrocaloric properties such as entropy change, heat capacity change and relative cooling power. The results indicate the potential of this ferroelectric compound to achieve the ECE near Curie temperature (TC). It is useful as prospective candidate for cooling system in a wide temperature interval. The maximum change in entropy near TC obtained by phenomenological model has been compared with the value procured by Tarnaoui et al. [1]. The results confirm that the phenomenological model is undoubtedly beneficial for the prediction of the electrocaloric effect of ferroelectric materials. [ABSTRACT FROM AUTHOR]

In this work, electrophysical features of the hard ferroelectric material PKP-35 are studied in a wide temperature range. Research object is a solid solution of lead zirconate-titanate (PZT) modified with some additives prepared by the conventional solid-state sintering method. The temperature dependences of the dielectric permittivity and dielectric losses in weak fields at frequencies of 1, 10, and 1000 Hz are obtained. The dielectric hysteresis loops at different temperatures are studied, the material features are revealed, the scope of application is determined. [ABSTRACT FROM AUTHOR]

Direct electrocaloric effect of BaTiO3-based ceramic materials was measured during poling and partial reverse poling using a square-wave electric field. A strong influence of the amplitude of the reverse bias field on the electrocaloric response was found. With increasing amplitude of the reverse bias field, the electrocaloric response was suppressed depending on the coercive field of the material and nature of the ferroelectric-to-paraelectric phase transition. [ABSTRACT FROM AUTHOR]

Boris A. Strukov, a former professor at Moscow State University, passed away in Munich, Germany at the age of 88. He made significant discoveries in the field of ferroelectric materials, particularly in observing phase transition phenomena. He authored a textbook on ferroelectrics and had a warm heart for helping young researchers. Strukov had a deep relationship with Japan, visiting the country multiple times and promoting joint research. After retiring, he lived a peaceful life in Munich with his family. [Extracted from the article]

In this paper, iterative optimization is carried out within the allowable range of mismatch of the crystal lattice, and the density of states, energy band, differential charge density and effective mass of the cell-electrode interface are calculated and analyzed. It is proposed to improve the application of ferroelectric LiNbO3-based electric-optic modulators with a better choice of electrodes, and can provide a carrier-transfer basis for the ferroelectric materials. And the calculation of the interface offered selection for the new materials electrode, to improve the efficiency in the electric-optic transfer and the storage efficiency in the future. [ABSTRACT FROM AUTHOR]

Epitaxial (Pb0.9La0.1)(Zi0.4Ti0.6)O3 (PLZT) film was prepared with Pt as the upper electrode and La0.5Sr0.5CoO3(LSCO) as the bottom electrode on (001) STO substrate by radio frequency (RF) magnetron sputtering. The dynamic hysteresis scaling behavior of the film, including the variation of remanent polarization (Pr), coercive field (Ec), and loop area () with external field (E0) and frequency (f) , was systematically studied. The evolution of scaling behavior in the PLZT film can be divided into two stages: minor loops and major loops, which are in the low and high E0 regions, respectively. The scaling relations take form of < A > ∝ f − 0.11 E 0 2.72 and < A > ∝ f − 0.03 E 0 1.27 in minor loops and major loops, respectively. The results show that the domain structure and domain reversal play an important role in the dynamic hysteresis behavior of ferroelectric materials. [ABSTRACT FROM AUTHOR]

The discrete Preisach model is popular to describe the hysteresis of smart materials, such as the piezoelectric and ferroelectric material. Re-explaining the discrete Preisach model of antiferroelectric materials after introducing an extended Preisach function, the special multilayer perceptrons with only two input nodes was designed intrinsically to satisfy the anticommutative property of hysteresis without superfluous hidden nodes (called aMLP), where its output equals to the difference between two predictive results that two signals in the normal and reverse sequence are imported to the aMLP model. Several training algorithms, including the normal/hybrid generic algorithm (GA) and the normal/hybrid particle swarm optimization (PSO), were used to adjust the parameters of the aMLP model, respectively. The comparing results indicate that the aMLP models designed with the winner operation function pair of [tanh, ReLU] and trained by both normal and hybrid PSO algorithms suggest the better performance when applying the working voltages more than 50 V according to the experimental data. It provides another accurate way for an aMLP model to estimate the anticommutative property of hysteresis of smart materials. [ABSTRACT FROM AUTHOR]

This investigation focuses on the phase structures, dielectric, ferroelectric and piezoelectric performances of (1−x)BiFe0.97Ga0.03O3–xBaTiO3 (x, 0.24–0.38) ceramics. A phase transition from rhombohedral to pseudocubic phase was identified as x increases. The morphotropic phase boundary (MPB) of rhombohedral–pseudocubic phase coexistence locates in a broad range of 0.26 ≤x ≤ 0.33. Particularly, both piezoelectric and ferroelectric performances of the materials near MPB were improved. For instance, high remanent polarization Pr of 23.3 μC/cm2 and piezoelectric coefficient d33 up to 173 pC/N were observed for 0.68BiFe0.97Ga0.03O3–0.32BaTiO3 ceramics. Furthermore, the ceramics near MPB has higher Curie temperature than that of the conventional Pb-based piezoceramics. [ABSTRACT FROM AUTHOR]

Nature has always amused us; sometimes it holds us in awe and sometimes it leaves us spellbound with its mysterious and inscrutable ways of working. The most significant and fundamental understanding of materials observed today is based on their constituent elements and position of the elements in the periodic table; which decides their property, behavior, reactivity and affinity with other elements. Given this primary aspects what comes secondary is the specificity or the multiplicity of functions that can be achieved from a material. In the present era, there is an incredible and massive increase in the number of functional materials to meet the ever-increasing need of electronic devices and their miniaturization. Functional materials have carved a special niche for itself in the field of material science. This review is exclusively intended to highlight and satiate the academic curiosity of novices about functional aspects of ferroelectric materials. It explores the various intricate and inherent principles and mechanisms which underpins the functional dimensions of ferroelectric materials. Ferroelectrics span a huge fraction of functional materials. Phenomenon like photovoltaic effect in ferroelectric materials, ferroelectric emission of electrons and their multifaceated applications are also discussed. Low dimensional ferroelectrics and their multifunctional prospects are also briefly covered in this review. It also includes brief idea of ferroelectric meta-materials, dielectric super-capacitors and its advantage over other preexisting ones. It is mostly informative and resourceful in providing multifunctional aspects of ferroelectrics. This review assures researchers who are genuinely interested in broadening their information base along with getting a fresh perspective into this emerging field of ferroelectrics as functional materials. [ABSTRACT FROM AUTHOR]

Václav Janovec, Czech theoretical physicist and enthusiastic promoter of symmetry approach to ferroic phase transitions and domain boundaries, passed away on Wednesday, February 16th, 2022, just a few days before his 92nd birthday. The most groundbreaking contribution of Václav Janovec was formulated in his publications devoted to the symmetry of domain walls (V. Janovec, Czech. His most cited work is a joint publication with J. Fousek, covering rules for the identification of all permissible planar ferroelectric walls (J. Fousek and V. Janovec, J. App. Phys. [Extracted from the article]

The results of studying ferroelectric materials obtained at the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences in 1973-2020 are reported. Mechanisms of the photovoltaic effect and photorefraction, emergence and role of polar regions in ferroelectric crystals, methods of detection of polar regions, and mechanisms of manifestation of the displacive and order-disorder phase transitions in various ferroelectrics are discussed. The results of experimental and theoretical investigations allow one to conclude that imperfections of a crystal structure play a key role in phenomena observed in ferroelectrics. [ABSTRACT FROM AUTHOR]

The present paper is devoted to the study on the dielectric properties and microstructure of samples of multicomponent ceramics of the PZT system with various Curie temperatures. The coexistence of two ferroelectric phases is shown. They behave differently during the poling process. The temperature dependence of the dielectric permittivity of pooled samples of compositions near the morphotropic phase boundary exhibits anomalies below the Curie temperature. [ABSTRACT FROM AUTHOR]

Barium titanate (BaTiO3) is a ferroelectric and piezoelectric material with excellent components. Barium titanate film success fully made with various concentration of CeO2 0%, 2%, 4%, and 6% through Chemical Solution Deposition (CSD) method in annealed process at 550 °C for 23.5 hours and the spin coating technique with a speed of 8000 rpm. The results of the crystal properties test showed that the lattice parameters with various concentration of CeO2 0%, 2%, 4%, 6% respectively a = b = 4.0491 Å and c = 4.0258 Å; a = b = 4.06267 Å and c = 4.0355 Å; a = b = 4.0549 Å and c = 4.0249 Å; a = b = 4.0547 Å and c = 4.0385 Å so that the crystal structure is tetragonal. The results of the optical properties test that the index refractive resulted in 1.4842, 1.4508, 1.4917, and 1.5175. The piezoelectric response test gets results of the piezoelectric voltage constant in the range 33.3322–43.1052 Vm/N, piezoelectric charge constants in the range 1.4700 × 10−7–1.9074 × 10−7 C/N and mechanical strain in the range 166.0147 to 329.1333. Based on characterization results and tested, cerium oxide doped barium titanate film have potential to develop being piezoelectric sensor. [ABSTRACT FROM AUTHOR]

The motion of domain walls and phase fronts in ferroelectric and ferroelastic materials displays discrete, impulsive jumps, i.e. jerks, as indicators of avalanches on a broad range of scales. Several experimental techniques used to characterise these avalanches show that they are power law distributed and share some statistical similarities with the avalanches observed during the compression of porous materials. Simulations attribute their origin to kinks and needle domains pinned by junctions between domain walls and show their evolution with the amplitude of the driving field. Recent studies on conductive and polar domain walls prove promising for the development of domain wall engineering. [ABSTRACT FROM AUTHOR]

The article presents a new method of electromechanical characterization of ferroelectric materials. The measurements of the complex elastic, electromechanical, and piezoelectric parameters of ferroelectric ceramics were fulfilled using the piezoelectric resonance analysis method. To study nonlinear processes occurring in ferroelectric ceramics under the external influences the dc electric field, dependencies of the complex electromechanical parameters of the PZT type piezoceramics were measured and analyzed. [ABSTRACT FROM AUTHOR]

A ferroelectric material (Bi0.5Na0.5)0.935Ba0.065TiO3 (BNBT) with a perovskite structure was poled and characterized by electrical impedance spectroscopy as a function of temperature, X-ray diffraction, and Rietveld refinement. The ac conductivity showed a low-frequency dispersion, supporting the idea of heterogeneous potential wells favored by Bi3+, Na+, and Ba2+ on the A site of the perovskite type of structure. The activation energies for ac conduction depende on the studied frequency. The permittivity and electrical modulus showed a distribution of the relaxation time associated with the delay in the orientation of the dipoles and an important contribution to the short-range conductivity. [ABSTRACT FROM AUTHOR]

Gold clusters are considered as widely used catalyst for chemical industry, but the efficiency of catalyst has been limited by the aggregation of the gold atoms, since the active sites are only located on the surface of the catalyst particles. In this paper the surface distribution of gold clusters influenced by spontaneous polarization and temperature is discussed. The morphology of the gold particle on different ferroelectric surface was simulated by the dissipative particle dynamics method, and the results are examined by pulsed laser deposition and Atomic Force Microscopy. The negatively poled surface with temperature adjustment could grow more dispersed gold clusters and offer a new progress to select the ferroelectric materials as the substrates for metal catalyst. [ABSTRACT FROM AUTHOR]

Pb(Sc1/2Nb1/2)O3 (PSN) with a perovskite structure is a well-known ferroelectric material. The rapidly quenched PSN (PSN-D) shows a B-site disordered structure, and exhibits the noncanonical relaxor behavior with Tmax=around 351 K. The well-annealed PSN (PSN-O) exhibits a B-site 1:1 ordered structure, and undergoes a normal ferroelectric phase transition at TC= about 346 K, while, the introduction of vacancies may lead to the broadening of dielectric peak with frequency dispersion down to low temperatures, typical of relaxor nature. It was reported that as-sintered ordered PSN (PSN-OV) with Pb/oxygen vacancies exhibits relaxor ferroelectric behavior with TC= about 292 K. In this work, the elastic anomaly of a longitudinal acoustic (LA) mode and the central peak of a PSN-OV crystal were studied by Brillouin scattering. The temperature dependences of the frequency shift and the width of the LA mode along the [100] direction were investigated. A broad elastic anomaly and a broad slowing down of the relaxation time were observed at the ferroelectric phase transition. The elastic anomaly of PSN-OV is compared with those of PSN-D and PSN-O crystals reported in our previous studies. It is found that the relaxor nature of PSN-OV caused by vacancies is stronger than that of PSN-D caused by the B-site disorder. [ABSTRACT FROM AUTHOR]

Nowadays, environment highly encounters various pollutants including toxic gases, organic volatiles and water pollutant. Many scientists have taken the effort to reduce or eliminate pollutant using photocatalytic materials. Due to good ferroelectric property in ferroelastic crystal as a result of the reduction in symmetry between the paraelastic and ferroelastic phases, it makes bismuth vanadate (BiVO4) one of attractive ferroelectric materials. In addition, BiVO4 with low optical band gap could be activated by visible light illumination so that it would be a potential candidate as a visible light driven photocatalyst. This work was carried out to synthesize BiVO4 nanoparticles by simple but effective method via sonochemical process through chemical route assisted by ultrasonic irradiation. The crystalline structure and surface morphologies of the synthesized products were observed by X-ray diffraction technique and Scanning Electron Microscope, respectively. Raman spectroscopy and Fourier Transform Infrared spectroscopy were used to approve the BiVO4 chemical bonding and relevant crystalline formation. Photocatalytic activity was studied by mean of the degradation of organic dye assigned as organic compound under visible light irradiation. [ABSTRACT FROM AUTHOR]

Strontium titanate (SrTiO3) which belongs to the ferroelectric material is very sensitive to wavelength. Therefore research on the effect of wavelengths on light absorbed by strontium titanate is very important. The results showed that the wavelength affected to the percentage adsorbed by the Strontium Titanate Trioxide linearly at various levels of concentration of Rudenium Oxide. The addition of the ARIMA Error model can improve the accuracy of the model. [ABSTRACT FROM AUTHOR]

Ferroelectric materials with tailored domain structures are promising "smart" substrates providing additional degrees of functionality for the graphene-based devices. We demonstrate the effect of periodical domain structure in lithium niobate substrate on the electrical properties of graphene studied by Raman spectroscopy. The spatial variations of the charge carriers and Fermi levels in graphene corresponding to oppositely polarized domains have been elucidated. The observed effects are supposed to be driven by the lateral component of electric field at the surface related to the gradient of spontaneous polarization. The five orders of magnitude decay of charge density in graphene is due to screening of depolarization field. [ABSTRACT FROM AUTHOR]

The presence of a finite conductivity results in the appearance of an electric current proportional to the strength of the electric field. In turn, this current leads to the appearance of a magnetic field. For the thermodynamic description of these phenomena, it is proposed to consider the free energy of a ferroelectric material containing both scalar and vector potentials in accordance with the Landau theory. The heat equation is derived, which includes both the conductivity itself and its temperature derivative. It is shown that the main contribution of conductivity is the existence of Joule heat. [ABSTRACT FROM AUTHOR]

The electrophysical and mechanical properties of a piezoceramic material based on a PZT are studied. Several features in the behavior of the electrophysical properties of the material in the temperature range located substantially lower than the low-frequency (1 kHz) maximum of the permittivity are revealed. The obtained results indicate the closeness of the material studied to ferroelectrics-relaxors, in particular, due to the low coercive field significant dependence of on the frequency and amplitude of the measuring field, and also the behavior of the velocity of longitudinal ultrasonic waves in the studied ceramics. [ABSTRACT FROM AUTHOR]

Lead-free ceramics of potassium-bismuth titanate K0.5Bi0.5TiO3 were obtained by a conventional sintering method under various technological conditions. The dielectric permittivity (ε) and dielectric loss (tan(δ)) measurements for these ceramics were carried out in the temperature range from 293 K to 873 K with the frequency range from 0.1 kHz to 2 MHz. An increase in dielectric permittivity with an increasing sintering temperature was observed. For the sample obtained at 1313 K and a 3.5-hour sintering time, the value of ε was about 4.55·103 (f = 100 kHz) which is twice higher than the value of ε for the sample obtained at a temperature of 1298 K and a 7-hour s sintering time. For all samples, the maximum value of dielectric permittivity was shifted towards higher temperatures with an increasing frequency, which is a characteristic feature s of ferroelectric relaxor materials. The dielectric properties of all materials were very similar, especially in the case of dielectric loss. The values of tan(δ) at room temperature varied from about 0.07 at 0.1 kHz to 0.1 at 2 MHz. The Raman studies were performed at room temperature. No significant changes were observed for different sintering temperatures and times for all samples. The presented material can be a starting point for the development of new ferroelectric relaxor materials. [ABSTRACT FROM AUTHOR]

Barium titanate BaTiO3 (BT) is one of the widely applied lead-free ferroelectric materials due to relatively high permittivity and low cost. Lead zinc-niobate Pb(Zn1/3Nb2/3)O3 (PZN) belongs to a class of disordered and inhomogeneous materials, i.e. is a relaxor. Low-lead (1-x)BT-xPZN ceramics (x = 0, 0.025, 0.05, 0.075, 0.1, 0.125 and 0.15) were prepared by two-step conventional oxide mixed sintering process. Thermal conductivity (κ) of these ceramics was measured for the first time (except for x = 0) from room temperature to 200 °C. It was shown that the thermal conductivity decreases with both decreasing temperature and with increasing PZN content. κ(T) curves show anomaly at Curie temperature, which is connected with change of specific heat. Obtained results indicated that thermal conductivity of investigated samples is mainly related to phonons scattering by lattice defects and by atomic mass fluctuation resulted from PZN incorporation to BT. [ABSTRACT FROM AUTHOR]

Multiferroic materials with magnetoelectric properties, due to their coupling between the electrical and magnetic properties have attracted the attention of many researchers. Perovskite structured materials based on BiFeO3 are a class of materials largely considered in these studies. In this work, Bi1-xNdxFe0.99Co0.01O3 (x = 0.05, 0.10 and 0.20) compositions were synthesized aiming a better understanding of the crystal and electronic structure role in ferroic properties of these materials. Structural studies were made by X-ray diffraction and Rietveld refinement; evidencing the rhombohedral symmetry of the samples with space group R3c. Electron density calculations were performed by the maximum entropy method. These studies showed that Nd3+ substitution causes distortions in the unit cell, which have influence on the magnetic properties. Also, the electron density maps showed the bonds between the iron and oxygen ions did not changed a lot. But the Minimum Electron Density observations were enough to conclude that the ferroelectric and the dielectric properties of Bi1-xNdxFe0.99Co0.01O3 compositions would be modified with the Nd3+ substitution. [ABSTRACT FROM AUTHOR]

BaTiO3-ceramics is a porous material made out of grains and pores. Such a structure is best explained by fractal nature approach. There is a strong porosity influence on microelectronic properties, so a pore itself acts as a microcapacitor with traces of inductivity. A cluster of pores than makes an integral impedance with an equivalent circuit scheme. Fractal nature theory approach helps modeling such microimpedance. The experimental data are acquired using SEM micro-graphs of the selected specimens. Further method is based on fractal analytic procedures based on extraction of fractal dimension and involving this as a key parameter. Such an approach, in combination with methods developed by the authors completes the extensive method for determination of relationship between microelectronic properties of sintered barium-titanate ceramics and technological parameters used in the sintering process. The issue of additives is also considered due the fact that dopants have considerable influence on electronic characteristics. Fractal analyzes and fractal dimension materials characterization are very important as a new tool with in the materials, electronic ceramics, and concretely ferroelectric applications. In this paper we applied fractal Cantor set and also developed fractal curvature tensor product. This enlighten new frontiers in electroceramics materials surface characterization. [ABSTRACT FROM AUTHOR]

During the last decades, increasing progresses have been made on the theoretical study of ferroelectric materials since the discovery of the barium titanate (BaTiO3). The ab-initio methods are based on quantum mechanics, which takes into account only fundamental physical constants. This work aims the study of the electronics properties of perovskite oxides based on BaTiO3, considering the inclusion of rare-earth ions as impurities into the structure, by using the density functional theory (DFT). The presence of structural defects, such as vacancies, as well as their influence on the physical properties, has been investigated. [ABSTRACT FROM AUTHOR]

The method of preparation of [NH3(CH2)3NH3]CuCl4 and [NH3(CH2)3NH3]CdBr4 crystals is given, and optical and dilatometric studies are presented. Optical polarized microscopic observation revealed multidomain states at room temperature orthorhombic phase with domain walls in (101) and (10-1) planes. The temperature dependence of the linear birefringence and the thermal expansion coefficient were measured and critical indices α and β were determined for the [NH3(CH2)3NH3]CdBr4 crystal. The linear birefringence and domain structure studies revealed the single first order transition in the [NH3(CH2)3NH3]CuCl4 crystal. [ABSTRACT FROM AUTHOR]

Local polarization exists in ferroelectric materials with diffuse phase transition even above the temperature at which the dielectric permittivity reaches its maximum (TM). The net polarization only cancels above the so-called Burns temperature (Td). In this work, polarization vs. temperature curves of Pb1−xCaxTiO3 (PCT) ceramics, with 0.35 ≤ x ≤ 0.55, were determined from experimental data of thermal expansion, considering strain and polarization relations and assuming that the electrostriction coefficient is constant in the paraelectric state. The Burns temperature was determined and compared to TM for each composition, and the achieved results indicate that a crossover from normal to diffuse phase transition occurs at x∼0.475. [ABSTRACT FROM AUTHOR]

Random electric fields (RF) due to charge disorder are at the origin of polar nanoregions (PNR) in the cubic relaxor PbMg1/3Nb2/3O3. They initiate Lacroix-Béné-type Cole-Cole semicircles, which achieve Cole-Davidson skew and dynamic power law criticality upon approaching superdipolar glass freezing. Below Tg ≈ 240 K percolation of PNR into microdomains is evidenced by interfacial creep and relaxation via Cole-Cole diagrams. Similar behavior occurs in uniaxial Sr0.8Ba0.2Nb2O6 (Tg ≈ 301 K). In contrast, matrix isolated ferromagnetic nanoparticles in CoFe/Al2O3 multilayers without RF interaction lack all of these effects except superglassy critical dynamics at Tg ≈ 46 K. [ABSTRACT FROM AUTHOR]

The static domain structure of ferroic Fe3B7O13I, (abbreviated as Fe-I) synthetic boracite crystals has been analyzed by polarized-light microscopy (PLM) and by field emission scanning electron microscopy (FE-SEM) at room temperature. As for most boracites, Fe-I shows dielectric, elastic, magnetic and optical properties of unusual interest. Upon cooling, Fe-I boracite shows a sequence of structural phase transitions from the cubic -43m to the orthorhombic mm2 (Tc = 348K), the monoclinic m (Tc = 218 K) and the trigonal 3m phases (Tc = 191 K). At room temperature, the Fe-I crystals present an orthorhombic domain structure which consists of six ferroic domains. Our results show that both techniques: PLM and FE-SEM are complementary for the visualization of ferroic domains. [ABSTRACT FROM AUTHOR]

Polarization-electric field hysteresis loops in 0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3 have been investigated near the ferroelectric critical temperature in the bipolar field applied along the [001]c direction in the pseudo-cubic coordinate. The double hysteresis loop has been observed above the transition temperature indicating the field induced transition, and the ferroelectric critical endpoint has been found at 192 °C and 1.6 kV/cm. The temperature field phase diagram under the electric field applied along the [001]c direction has been clarified. [ABSTRACT FROM AUTHOR]

Lithium tantalate is a well-known optical crystal. The dispersion relation of phonon-polaritons was studied in ferroelectric lithium tantalate crystals. The reflectivity spectra of E//x and E//z polarizations, which are related to E(x,y) and A1(z) symmetry modes respectively, were measured by the FT-IR measurement in the far- and mid-IR regions. The dispersion relation of phonon-polariton frequency against real and imaginary parts of polariton wavevector was determined. E(x,y) and A1(z) symmetry polariton modes were also studied by forward Raman scattering. By the combination with the observed polariton dispersion relation determined by forward Raman scattering and terahertz time-domain spectroscopy, the broadband polariton frequency dispersion was determined between 10 cm−1 and 1200 cm−1. [ABSTRACT FROM AUTHOR]