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Atomistic model calculations recently revealed that the polarization pattern at the cross section through nanoscale ferroelectric nanodomains in rhombohedral barium titanate shows a clear antiskyrmion attributes such as the net invariant topological charge of minus two. The present work confirms that these topological defects also exist as local minima in the discretized Ginzburg–Landau–Devonshire model, which is widely used in phase-field modeling studies. We explore by phase-field simulations how an electric field can be used to create or move antiskyrmions within a monodomain ferroelectric matrix. The process of field-induced antiskyrmion annihilation reveals the existence of a discrete ladder of intermediate antiskyrmion states with distinct radii but common symmetry, topology, and geometrical properties. [ABSTRACT FROM AUTHOR]

The development of dielectric capacitors toward high voltage and high power density requires materials with excellent insulation and energy storage performances. In this work, a polymer dielectric with polyetherimide (PEI) as the matrix and calcium barium zirconate titanate (BZCT) coated by barium titanate fiber (BT) as the filler (BZCT@BT) was constructed. The (0.5%–10% BZCT@BT/PEI) polymer dielectric has an excellent discharge energy density (Ue) of 6.66 J/cm3 and maintains an advanced charge/discharge efficiency (η) of 93.29% when the BT content was 0.5% and the BZCT particle content was 10%. The addition of BZCT endows the polymer dielectric with a higher relative dielectric constant (εr), while BT, maintaining a lower εr than BZCT, could reduce the electric field (E) distortion caused by the dielectric mismatch between PEI and BZCT. Oriented fiber fillers increase the breakdown strength of the polymer dielectric, ultimately increasing the performance of energy storage. A new strategy for the design of energy storage polymer dielectrics was provided by this work. [ABSTRACT FROM AUTHOR]

Ferroelectric materials play a crucial role in a broad range of technologies due to their unique properties that are deeply connected to the pattern and behavior of their ferroelectric (FE) domains. Chief among them, barium titanate (BaTiO 3 ; BTO) sees widespread applications such as in electronics but equally is a ferroelectric model system for fundamental research, e.g., to study the interplay of such FE domains, the domain walls (DWs), and their macroscopic properties, owed to BTO's multiple and experimentally accessible phase transitions. Here, we employ Second Harmonic Generation Microscopy (SHGM) to in situ investigate the cubic-to-tetragonal (at ∼ 126 ° C) and the tetragonal-to-orthorhombic (at ∼ 5 ° C) phase transition in single-crystalline BTO via three-dimensional (3D) DW mapping. We demonstrate that SHGM imaging provides the direct visualization of FE domain switching as well as the domain dynamics in 3D, shedding light on the interplay of the domain structure and phase transition. These results allow us to extract the different transition temperatures locally, to unveil the hysteresis behavior, and to determine the type of phase transition at play (first/second order) from the recorded SHGM data. The capabilities of SHGM in uncovering these crucial phenomena can easily be applied to other ferroelectrics to provide new possibilities for in situ engineering of advanced ferroic devices. [ABSTRACT FROM AUTHOR]

Oxygen defects are introduced into PbZr0.5Ti0.5O3 films and their impact on ferroelectric behavior, linear dielectric response (LDR), and nonlinear dielectric response (NDR) is studied. Apart from a notable decrease in both polarization and LDR permittivity, the frequency spectra of LDR exhibit a distinctive loss peak. The peak position varies with temperature and oxygen defect concentration. NDR parameters, including the Rayleigh coefficient (α1), the slope (α2) correlating the imaginary part of permittivity with the ac electric field, and the slope (k) between the real and the imaginary parts of permittivity, demonstrate diverse behaviors in response to temperature and oxygen defect concentration. The similarity in the frequency spectra of tanδ and 1/k reveals the correlation between LDR and NDR induced by the presence of oxygen defects. These observations are attributed to the behavior of the single and composite defects associated with oxygen vacancies. [ABSTRACT FROM AUTHOR]

Layered thin films of the ferroelectric perovskite Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) and the ferromagnetic half-metal La0.80Sr0.20MnO3 (LSMO) are well-known multiferroic systems that show promise for spintronic applications. In this work, the structure–property relationships are explored in novel BCZT/LSMO thin film heterostructures with optimized ferroic properties. Epitaxial BCZT/LSMO thin film heterostructures are grown by varying the lattice mismatch strains on single crystal LaAlO3 (LAO) (100) and MgO (100) substrates using the pulsed laser deposition technique. The epitaxial strain in the films gives rise to a tetragonal distortion of the BCZT and LSMO unit cells and significantly affects their magnetotransport and magnetodielectric properties. The BCZT/LSMO/LAO heterostructure exhibits a colossal magnetoresistance effect due to a large out-of-plane tensile strain, which induces enhanced carrier hopping in the LSMO layer as compared to the BCZT/LSMO/MgO film. The larger tetragonal distortion of the BCZT unit cell in BCZT/LSMO/MgO contributes to higher dielectric permittivity, with a greater dielectric maxima temperature and freezing temperature. Magnetodielectric measurements reveal a hitherto unobserved giant magnetodielectric effect in the BCZT/LSMO/MgO film, attributed to a large in-plane strain, which induces interfacial polarization distortion at the interfacial layer. Overall, this work elucidates the unique strain and charge-mediated cross-coupled phenomena of magnetic and electric orders in multiferroic thin film heterostructures, which are critical for their technological applications. [ABSTRACT FROM AUTHOR]

The functional properties of piezoelectric ceramic materials, such as barium titanate, are highly dependent on grain size. Lead-free polycrystalline Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) samples were prepared with a combination of the hydrothermal method and spark plasma sintering to achieve grain sizes from 100 nm to 10 μm by varying the maximum sintering temperature. In this range, a transition from a nearly linear dielectric to a ferroelectric response can be seen in macroscopic electromechanical measurements, demonstrating the importance of grain size on functional properties in BCZT. Furthermore, in situ electric field-dependent synchrotron x-ray diffraction measurements were performed to quantify the intrinsic and extrinsic strain contributions and their variations with grain size. At lower grain sizes, the data revealed a significant loss of extrinsic contributions in the piezoelectric behavior, limiting the response to intrinsic contribution associated with lattice strain. For BCZT, a critical grain size between approximately 0.08 and 0.18 μm is proposed, below which no piezoelectric response was observed. [ABSTRACT FROM AUTHOR]

This study analyzes the regulatory mechanism of oxygen vacancy concentration on tail-to-tail charged domain walls (T–T CDWs), along with the writing time, conduction current magnitude, and retention performance of through-type T–T CDWs. The research results show that the highest density and length of T–T CDWs are achieved when the oxygen vacancy concentration is 1 × 1020 cm−3. Moreover, the successful writing of through-type T–T CDWs is limited to a certain electric field range, which is controlled by oxygen vacancy concentration. An increase in the oxygen vacancy concentration leads to a decrease in the maximum and minimum threshold electric fields required for writing through-type charged domain walls. The writing time and conductivity of through-type T–T CDWs determine the information writing speed and signal strength of domain wall memories, and the oxygen vacancy concentration also plays a regulatory role in both aspects. When the oxygen vacancy concentration is 1 × 1020 cm−3, the through-type T–T CDW exhibits the fastest writing speed, requiring only 8 ns. The magnitude of the conduction current of through-type T–T CDWs is directly proportional to the oxygen vacancy concentration. The through-type T–T CDWs formed by the aggregation of oxygen vacancies exhibit excellent retention performance, making them highly promising for applications in ferroelectric domain wall memories. Our research demonstrates that oxygen vacancies have a significant regulatory effect on the morphology and current response of charged domain walls, opening up new avenues for the study of domain wall memories. [ABSTRACT FROM AUTHOR]

A Landau–Devonshire thermodynamic energy density function for ferroelectric wurtzite aluminum scandium nitride (Al1−xScxN) solid solution is developed. It is parametrized using available experimental and theoretical data, enabling the accurate reproduction of composition-dependent ferroelectric properties, such as spontaneous polarization, dielectric permittivity, and piezoelectric constants, for both bulk and thin films. The maximum concentration of Sc for the wurtzite structure to remain ferroelectric is found to be 61 at. %. A detailed analysis of Al1−xScxN thin films reveals that the ferroelectric phase transition and properties are insensitive to substrate strain. This study lays the foundation for quantitative modeling of novel ferroelectric wurtzite solid solutions. [ABSTRACT FROM AUTHOR]

Ferroelectric transition and polarization characteristics were explored for filled tungsten bronze Ba4Sm2Ti4Nb6O30 ceramics with pinched P–E hysteresis loops. Two dielectric permittivity peaks were observed at around 553 and 486 K on heating and cooling cycles, respectively, with a large thermal hysteresis (∼77 K), indicating the first-order ferroelectric phase transition behavior in the present ceramics. In addition, a low-temperature dielectric relaxation appeared at around 300 K, following the Vogel–Fulcher relationship, which is related to thermal activation related to the polarization in the ab plane. Pinched P–E hysteresis loops were detected in the temperature range of 293–453 K with two pairs of coercive fields, indicating certain polar reversal mechanism, while E1 corresponds to the reversal field needed for all the ferroelectric domains in the system, and E2 is the back switch field from the polar state to the nonpolar state. Therefore, (E1–E2)/2 is the effect coercive field for the polar domain induced by the field transition. Temperature dependence of the coercive fields E1, E2, and (E1–E2)/2 is fitted to the Vopsaroiu model with different activated energies obtained for different temperature ranges, based on which the polarization dynamics of the pinched hysteresis loops are discussed. [ABSTRACT FROM AUTHOR]

The microstructures, leakage conduction and energy storage performances of Gadolinium (Gd3+) modified barium calcium zirconate titanate based thin films [Ba (0.85-x) Ca 0.15 Gd x ][Zr 0.2 Ti 0.8 ]O (3+0.5x) (x = 0, 0.005, 0.0075 and 0.01) prepared on the Pt/Ti/SiO 2 /Si substrates using sol-gel method were characterized and analyzed. The dense and uniform microstructure with fine nanocrystalline grains is obtained in low Gd3+ concentration (x ≤ 0.0075) doped BCGZT thin films with single phase perovskite structure. With the increase of Gd3+ content, the leakage current density of BCGZT films initially decreases to the minimum at x = 0.0075 due to the existing of defect dipoles V Ca ″-V O •• caused by the Gd3+ substitution for A site ions and then increases significantly due to the appearance of impurity phases. With the increase of electric field, the leakage mechanism for each BCGZT film transforms from ohmic conduction and/or SCL conduction to F-N tunneling. The remanent polarization keeps decreasing because of the weakened ferroelectricity of Gd3+ modified BCZT perovskites and the decreasing average grain size as the Gd3+ content increases. The BCGZT thin film with x = 0.0075 possesses an enhanced energy storage density of 55.1 J/cm3 and an acceptable energy storage efficiency of 67.1 % at the ultra-high breakdown field of 4300 kV/cm, which is promising for capacitor applications. [ABSTRACT FROM AUTHOR]

BaTiO3 has been investigated nearly several decades due to its excellent ferroelectric and dielectric properties. However, the property evolution of BaTiO3 with a particle size of sub-10 nm is still unclear because of the difficulty during the fabrication and characterization. Here, a series of BaTiO3 nanoparticles with the average particle sizes of 2.8, 4.5 and 8.1 nm are achieved, and their phase structure, ferroelectric and dielectric properties are skillfully characterized. With the particle size decreasing from 8.1 to 2.8 nm, the nanoparticles show a declining non-centrosymmetry, nonlinear response, ferroelectricity and dielectric constant. Nevertheless, the 2.8 nm BaTiO3 nanoparticles still possess observable second harmonic generation, ferroelectric polarization switching behavior and butterfly loop, showing weak but distinguishable ferroelectricity. This research depicts a detailed ferroelectric and dielectric property evolution in sub-10 nm BaTiO3 nanoparticles, which provides theoretical basis and promising candidate for the future ferroelectric applications. [ABSTRACT FROM AUTHOR]

In this article, BaTiO 3 -xCaCu 3 Ti 4 O 12 /TiO 2 composite ceramics (where x = 0.02, 0.04, 0.06, 0.08, 0.1, 0.2) were successfully prepared by a solid-state technique and sintering at 1100 °C. The XRD results show that a small amount of Ba 2 Ti 5 O 12 and CuO exists in the obtained composite ceramics, originating from CaCu 3 Ti 4 O 12 /TiO 2 (CCTO/TiO 2) decomposition and recombination with the excess TiO 2. The microstructure investigation confirms that the added CCTO/TiO 2 particles have pomegranate-like grain distribution embedding in the matrix of BaTiO 3. The obtained composite ceramics exhibit a giant dielectric constant (3 × 104-1.5 × 105, at 25 Hz) at room temperature, attributed to the synergistic effect of spontaneous polarization of ferroelectric BaTiO 3 , electronic polarization of CCTO, and hierarchical interface polarization. [ABSTRACT FROM AUTHOR]

AbstractThis research utilized higher-order shear deformation theory to model and analyze the thermomechanical vibration buckling behavior of auxetic core layered smart sandwich plates. The surface layers of the smart plate consist of magneto strictive CoFe2O4 (Cobalt Ferrite) and electro elastic BaTiO3 (Barium Titanate) materials. The hexachiral auxetic core layer consists of the metal biomaterial Ti-6Al-4V, which includes various auxetic cell parameters. This study analyses the effects of Auxetic core layer parameters on the thermo-mechanical vibration buckling behavior of the smart sandwich plate, along with the influence of external electrical and magnetic potentials applied to the surface plates over a wide range. The findings demonstrate that the thermo-mechanical buckling behavior of the smart sandwich plate can be regulated by appropriately adjusting the Auxetic cell and applying external electric and magnetic potentials. The findings of this study will facilitate the design of smart electromechanical systems suitable for high-temperature environments. [ABSTRACT FROM AUTHOR]

An Integrated Process Intensification (IPI) technology-based roadmap is proposed for the utilization of renewables (water, air and biomass/unavoidable waste) in the small-scale distributed production of the following primary products: electricity, H2, NH3, HNO3 and symbiotic advanced (SX) fertilizers with CO2 mineralization capacity to achieve negative CO2 emission. Such a production platform is an integrated intensified biorefinery (IIBR), used as an alternative to large-scale centralized production which relies on green electricity and CCUS. Hence, the capacity and availability of the renewable biomass and unavoidable waste were examined. The critical elements of the IIBR include gasification/syngas production; syngas cleaning; electricity generation; and the conversion of clean syngas (which contains H2, CO, CH4, CO2 and N2) to the primary products using nonthermal plasma catalytic reactors with in situ NH3 sequestration for SA fertilizers. The status of these critical elements is critically reviewed with regard to their techno-economics and suitability for industrial applications. Using novel gasifiers powered by a combination of CO2, H2O and O2-enhanced air as the oxidant, it is possible to obtain syngas with high H2 concentration suitable for NH3 synthesis. Gasifier performances for syngas generation and cleaning, electricity production and emissions are evaluated and compared with gasifiers at 50 kWe and 1–2 MWe scales. The catalyst and plasma catalytic reactor systems for NH3 production with or without in situ reactive sequestration are considered in detail. The performance of the catalysts in different plasma reactions is widely different. The high intensity power (HIP) processing of perovskite (barium titanate) and unary/binary spinel oxide catalysts (or their combination) performs best in several syntheses, including NH3 production, NOx from air and fertigation fertilizers from plasma-activated water. These catalysts can be represented as BaTi1−vO3−x{#}yNz (black, piezoelectric barium titanate, bp-{BTO}) and M(1)3−jM(2)kO4−m{#}nNr/SiO2 (unary (k = 0) or a binary (k > 0) silane-coated SiO2-supported spinel oxide catalyst, denoted as M/Si = X) where {#} infers oxygen vacancy. HIP processing in air causes oxygen vacancies, nitrogen substitution, the acquisition of piezoelectric state and porosity and chemical/morphological heterogeneity, all of which make the catalysts highly active. Their morphological evaluation indicates the generation of dust particles (leading to porogenesis), 2D-nano/micro plates and structured ribbons, leading to quantum effects under plasma catalytic synthesis, including the acquisition of high-energy particles from the plasma space to prevent product dissociation as a result of electron impact. M/Si = X (X > 1/2) and bp-{BTO} catalysts generate plasma under microwave irradiation (including pulsed microwave) and hence can be used in a packed bed mode in microwave plasma reactors with plasma on and within the pores of the catalyst. Such reactors are suitable for electric-powered small-scale industrial operations. When combined with the in situ reactive separation of NH3 in the so-called Multi-Reaction Zone Reactor using NH3 sequestration agents to create SA fertilizers, the techno-economics of the plasma catalytic synthesis of fertilizers become favorable due to the elimination of product separation costs and the quality of the SA fertilizers which act as an artificial root system. The SA fertilizers provide soil fertility, biodiversity, high yield, efficient water and nutrient use and carbon sequestration through mineralization. They can prevent environmental damage and help plants and crops to adapt to the emerging harsh environmental and climate conditions through the formation of artificial rhizosphere and rhizosheath. The functions of the SA fertilizers should be taken into account when comparing the techno-economics of SA fertilizers with current fertilizers. [ABSTRACT FROM AUTHOR]

This study presents a detailed comparative analysis of three electron transport layer (ETL) materials for perovskite solar cells (PSCs), namely titanium dioxide (TiO2), barium titanate (BaTiO3 or BTO), and strontium-doped barium titanate (Ba1−xSrxTiO3 or BST), and their impact on the quantum efficiency (QE) and power conversion efficiency (PCE) of CH3NH3PbI3 (MAPbI3) PSCs. The optimized structure demonstrates that devices utilizing BST as an ETL achieved the highest PCE of 29.85%, exhibiting superior thermal stability with the lowest temperature coefficient of − 0.43%/K. This temperature-induced degradation is comparable to that of commercially available silicon cells. Furthermore, BST-based ETLs show 29.50% and 26.48% higher PCE than those of TiO2-based and BTO-based ETLs. The enhanced internal QE and favorable current density–voltage (J–V) characteristics of BST compared with those of TiO2 and BTO are attributed to its improved charge carrier separation, reduced recombination rates, and robust electrical characteristics under varied environmental conditions. Furthermore, the electric field and generation rate of the BST-based ETLs show a more favorable distribution than those of the TiO2-based and BTO-based ETLs. These findings provide significant insights into the role of different ETLs in enhancing QE, indicating that BST is a superior ETL that enhances both the efficiency and stability of PSCs. This study contributes to the understanding of how perovskite-structured ETLs can be used to design and optimize highly efficient and stable photovoltaic devices. [ABSTRACT FROM AUTHOR]

The Curie point of barium titanate (BaTiO3) has been a focal point of research since the discovery of its ferroelectric properties. Exploring methods to elevate the Curie point without relying on Pb as a dopant presents fresh opportunities for lead-free dielectric and/or piezoelectric materials. It is essential to avoid introducing ions like K + and Na + , which could jeopardize the functional ceramic characteristics. This study delves into the stoichiometry of barium titanate, examining how impurities, point defects and doping techniques influence its Curie point, focus on the potential of doping and processing to enhance this property. BaTiO3 nanopowders were synthesized directly with varying Ba:Ti ratios in an ethanol–water solution at 60∘C, followed by sintering at 1280∘C and characterization through dielectric spectroscopy. A comparison was made with samples doped with Si, vapor-doped with Bi and vapor-doped with Pb. Results revealed that even minimal Si doping could boost the ferroelectric properties and elevate the Curie point, while vapor-doping with trace amounts of PbO or Bi2O3 significantly increased the Curie point, particularly in samples with higher Ti content. The impact of vapor dopants of PbO and Bi2O3 was similar, with a nominal doping level of 1 mol% shifting the Curie point above 140∘C. Notably, in samples with a Ba:Ti ratio of 0.95 vapor-doped with PbO, the Curie point rose to 146∘C, a notable increase of 16∘C, surpassing the traditional doping efficiency. This study offers fresh insights into enhancing the Curie point of barium titanate-based materials, exploring the intricate connections among chemical stoichiometry, dopants, point defects and dielectric properties. It highlights the significant influence of chemical composition, impurities, defects and doping strategies on the dielectric characteristics of barium titanate. [ABSTRACT FROM AUTHOR]