BaTiO3 Shell Research Articles

CoFe2O4-BaTiO3 core-shell-embedded flexible polymer composite as an efficient magnetoelectric energy harvester

Flexible magnetoelectric (ME) generators gained immense interest due to the broad applications in wearable and Internet of Things (IoT)-based devices. The key to achieving high energy conversion performance of 0–3 type ME composite films is the prevention of filler aggregation in the polymer matrix and accessing the full potential of intrinsic properties of filler. To achieve high performance, a flexible ME composite film was fabricated by homogeneous distribution of magnetostrictive CoFe2O4-BaTiO3 core-shell (CBCS) fillers into piezoelectric polyvinylidene fluoride (PVDF) polymer. The ME composite film generates an enhanced energy conversion efficiency by optimizing the shell thickness of CBCS and maximizing the electroactive β-phase at the BaTiO3 shell-PVDF interfacial region. The observed ME coefficient of the film reached up to 710 mV/cm∙Oe. Multiphysics simulations based on the finite element analysis were adopted to investigate the role of BaTiO3 shell thickness on the performance of ME film. This study paves the way to achieve higher filler loading content in the ME composite films to develop an efficient, flexible ME generator for eco-friendly permanent power sources.

Cobalt Ferrite@Barium titanate core-shell nanoparticles empowered triboelectric electromagnetic coupled nanogenerator for self-powered electronics

In pursuing sustainable energy solutions for wearable technology and Internet of Things (IoT) devices, achieving high power in self-powered electronics is a significant challenge. This study introduces a novel hybrid nanogenerator by integrating a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) to achieve both high voltage and high current outputs simultaneously. The cobalt ferrite barium titanate (CoFe2O4@ BaTiO3) core–shell nanoparticles (NPs) were chosen for their unique ability to enhance the system’s performance by combining triboelectric, piezoelectric, and electromagnetic properties. The BaTiO3 shell exhibited robust triboelectric and piezoelectric properties essential for TENG operation, while the CoFe2O4 core, influenced by the EMG’s magnetic field, induces additional static charges, significantly boosting overall energy conversion efficiency. The TENG and EMG in the combined system operate together in a contact-separation mode, where their in-phase output signals are seamlessly combined via a double bridge rectifier, resulting in a robust power output of 37.7 mW and a power density of 1.86 mW/cm2, with cycling stability of over 10,000 cycles. The uniquely designed TENG-EMG combined nanogenerator (C-TENG) exhibited striking adaptability, effectively operating across different low-to-high frequencies and load situations while constantly powering portable electronic devices. This innovative approach meets the high energy demands of modern self-powered electronics with exceptional efficiency, durability, and high-power density, positioning it as a versatile solution for wearable biomechanical energy harvesting.

Achieving Excellent Dielectric and Energy Storage Performance in Core-Double-Shell-Structured Polyetherimide Nanocomposites.

The development of pulse power systems and electric power transmission systems urgently require the innovation of dielectric materials possessing high-temperature durability, high energy storage density, and efficient charge-discharge performance. This study introduces a core-double-shell-structured iron(II,III) oxide@barium titanate@silicon dioxide/polyetherimide (Fe3O4@BaTiO3@SiO2/PEI) nanocomposite, where the highly conductive Fe3O4 core provides the foundation for the formation of microcapacitor structures within the material. The inclusion of the ferroelectric ceramic BaTiO3 shell enhances the composite's polarization and interfacial polarization strength while impeding free charge transfer. The outer insulating SiO2 shell contributes excellent interface compatibility and charge isolation effects. With a filler content of 9 wt%, the Fe3O4@BaTiO3@SiO2/PEI nanocomposite achieves a dielectric constant of 10.6, a dielectric loss of 0.017, a high energy density of 5.82 J cm-3, and a charge-discharge efficiency (η) of 72%. The innovative aspect of this research is the design of nanoparticles with a core-double-shell structure and their PEI-based nanocomposites, effectively enhancing the dielectric and energy storage performance. This study provides new insights and experimental evidence for the design and development of high-performance dielectric materials, offering significant implications for the fields of electronic devices and energy storage.

In situ activation of flexible magnetoelectric membrane enhances bone defect repair

For bone defect repair under co-morbidity conditions, the use of biomaterials that can be non-invasively regulated is highly desirable to avoid further complications and to promote osteogenesis. However, it remains a formidable challenge in clinical applications to achieve efficient osteogenesis with stimuli-responsive materials. Here, we develop polarized CoFe2O4@BaTiO3/poly(vinylidene fluoridetrifluoroethylene) [P(VDF-TrFE)] core-shell particle-incorporated composite membranes with high magnetoelectric conversion efficiency for activating bone regeneration. An external magnetic field force conduct on the CoFe2O4 core can increase charge density on the BaTiO3 shell and strengthens the β-phase transition in the P(VDF-TrFE) matrix. This energy conversion increases the membrane surface potential, which hence activates osteogenesis. Skull defect experiments on male rats showed that repeated magnetic field applications on the membranes enhanced bone defect repair, even when osteogenesis repression is elicited by dexamethasone or lipopolysaccharide-induced inflammation. This study provides a strategy of utilizing stimuli-responsive magnetoelectric membranes to efficiently activate osteogenesis in situ.

Thermally controlled structural strain reduction in core shell magnetoelectric nanocomposite

In this research, we have presented detailed studies of the effect of temperature-controlled hydrothermal fabrication techniques on the morphology and structural strain in magnetoelectric core-shell nanocomposite having magnetic CoFe2O4 core coated with a piezoelectric BaTiO3 shell. We have presented the effect of controlled cooling rate during annealing process of synthesis on the structural integrity and structural strain of the core-shell hetero-nanostructure. Using temperature controlled hydrothermal method, it has been observed that controlling the cooling rate to 20 °C/min while annealing process leads to low structural strain on the deposited BaTiO3 shell. This also leads to high structural integrity of the fabricated heterostructure nanocomposite. To measure the strain distribution in the coated shell, geometric phase analysis was performed on the high-resolution transmission electron microscopic image of the fabricated core-shell nanostructure. Semi quantitative Energy-dispersive X-ray spectroscopy line scan elemental mapping have confirmed the elemental distribution throughout the nanostructure and formation of the core–shell structure. Moreover, through the geometric phase analysis, the core and the shell can be distinctively visualized which confirms the homogeneity of the coating of single crystalline BaTiO3 shell on the CoFe2O4 core.

Piezo-photoelectric all-in-one coaxial hierarchical TiO2-BaTiO3-CuInS2 heterostructure for synergistic water splitting

Rational multiple-field coupling, component control, and microarchitectures design for utilization of multiform driving forces as well as benefiting charge-carrier separation and migration is considered to be an outstanding approach to improve water splitting efficiency for alleviating increasing environmental problems. Herein, a novel piezo-photoelectric catalyst, coaxial TiO2-BaTiO3-CuInS2 heterostructures, was designed for efficient hydrogen production, synergistically driven by mechanical force, electricity, and light. The vertical growth of TiO2 nanorods guarantees sufficient generation of photoinduced charges and their fast migration. Electric field generated by the piezoelectric BaTiO3 shell under a mechanical driving force will promote the separation and transfer of photogenerated charge carriers, thereby minimizing the probability of charge recombination. The further incorporation of the outermost layer of CuInS2 is beneficial to broaden light harvesting. Of particular importance is the cascade band arrangement of the three different functional components, which greatly enhances the transfer of photo- and piezoelectrically induced charges. With the synergy of enhanced light harvesting, energy band engineering, and nanostructure interfacial design, the fabricated TiO2-BaTiO3-CuInS2 photoelectrode has achieved significant enhancement of piezo-photoelectric hydrogen evolution efficiency and could be expanded for pollutant decomposition. This simple yet general strategy provides valuable guidance for cooperatively capitalizing on piezoelectricity to engineer high-performing energy conversion and environmental protection.

A long-standing polarized electric field in TiO2@BaTiO3/CdS nanocomposite for effective photocatalytic hydrogen evolution

Ferroelectrics have the advantage of spatially separating the photogenerated charge carriers via the spontaneous polarized electric field, although the strength of the polarized electric field may suffer from the influence of the electrostatic shielding effect, which could reduce the charge carrier separation without mechanical stress. Herein, we developed a novel CdS decorated TiO2@BaTiO3 core–shell nanocomposite, where the optimal ratio of TiO2, BaTiO3 and CdS are 53.43, 37.37 and 9.20 wt%, respectively, for the best photocatalytic activity. The TiO2@BaTiO3/CdS nanocomposite reported in this work offers a persistent electric field in the ferroelectric BaTiO3 shell, due to the limited shielding effect in an asymmetrically polarized field. With the built-in electric field as the driving force, the photogenerated electrons and holes flowed into the CdS surface and the TiO2 core, respectively, with improved charge separation to participate in water-splitting reactions. The measured charge carrier lifetime of TiO2@BaTiO3/CdS nanocomposite via transient fluorescence spectrum is 0.42 ns, which is much longer than the TiO2 (0.25 ns) and TiO2@BaTiO3 (0.31 ns) samples. The TiO2@BaTiO3/CdS nanocomposite shows an enhanced photocatalytic hydrogen evolution rate of 13.22 mmol/g∙h under visible light illumination with an AQE of 52.50 % at 405 nm monochromatic light. This is much better than their components and binary composites, including TiO2/Pt (0.63 mmol/g∙h), CdS (1.23 mmol/g∙h), TiO2@BaTiO3 (0.03 mmol/g∙h), TiO2/CdS (0.53 mmol/g∙h), and BaTiO3/CdS (2.62 mmol/g∙h). This work provides an effective strategy for the construction of a ferroelectric photocatalyst with much-improved charge separation by the permanent internal electric field.

Construction of ternary core-shell Fe3O4@BaTiO3/PVDF nanocomposites with enhanced permittivity and breakdown strength for energy storage

Introducing conductive nanoparticles into ferroelectric polymers gives rise to significant enhancement of permittivity (ε), making these composites practically promising for energy storage devices. However, the breakdown strength (EB) of such composites is reduced with few exceptions, which limits high-performance applications. Here we study the energy storage behavior of well-designed Fe3O4@BaTiO3 core-shell nanoparticle/poly(vinylidene fluoride) (PVDF) nanocomposites in which conductive Fe3O4 nanoparticles (NPs) are coated by ferroelectric BaTiO3 (BT), together with the PVDF matrix, forming the ternary nanocomposite films with high energy storage performance. Notably, the permittivity is enhanced by increasing the volume fraction of the Fe3O4@BT NPs, reaching 38 with 2 vol% Fe3O4@BT NPs and remaining low dielectric loss (~0.066). In particular, the nanocomposites exhibit moderate breakdown strength (~430 kV/mm), which is attributed to the “voltage dispersion layer” (the BaTiO3 shell) between the polymer matrix and Fe3O4 NPs. The finite element simulation substantiates the experimental results and further confirms the positive correlation of the breakdown strength and the permittivity of the “voltage dispersion layer”. With the synergistic effect of both breakdown strength and electric displacement, a remarkable energy density (16 J/cc, at 430 kV/mm) is obtained.

Stable high thermal conductivities in BaTiO3 ceramic composites utilizing core-shell Ag@BaTiO3 particles

Ceramic/metal composites have drawn much attention in heat dissipations due to excellent performances, however, issues rise with the uncontrollable architecture and unstable properties resulting from metal-particle fusions at the high-temperature sintering. This study reports a BaTiO3 (BT) composite at a high Ag loading of 60 vol% with a stable composite architecture achieved by utilizing core-shell Ag@BT particles. Conformal-coated Ag@BT particles are prepared by simultaneous hydrolysis. The BT shell is vital in keeping Ag particles separately distributed and the shape well-retained in the BT matrix before and after the sintering to exhibit controllable structures. A high thermal conductivity of 84 W/mK is obtained in the composite at 25 °C, 35-fold enhanced compared with that of the BT ceramic of 2.4 W/mK. Low thermal barrier resistances as well as the nonpercolative behavior attributing to high thermal conductivities are owing to the unique composite architecture. The composite exhibits small fractures at Ag-BT interfaces while no macro fractures across the material are observed after the thermal cycling test. This study presents a BT/Ag@BT composite for various heat dissipation applications.

Magnetic and magnetoelectric response of Gd doped nickel ferrite and barium titanate nanocomposites

Composites of NiFe2O4 (NFO)–BaTiO3 (BTO) and NiGd0.01Fe1.99O4 (G0.01)–BTO were investigated by x-ray diffraction, magnetization, transmission electron microscopy, magnetocapacitance, and ferroelectric studies. NFO and G0.01 nanoparticles were synthesized by the sol-gel method. The crystallite size of the nanoparticles estimated from the x-ray diffraction patterns is 20–22 nm. The average crystallite sizes of NFO and G0.01 nanoparticles were estimated from the transmission electron micrographs as 26 (1) nm and 22.3 (0.3) nm, respectively. These nanoparticles were encapsulated in a BTO shell, resulting in the formation of nanocomposites. Room temperature magnetization (at 60 kOe) of G0.01 nanoparticles was found to be slightly higher than that of NFO nanoparticles, due to the larger moment of Gd3+ than that of Fe3+. Also, the magnetization of G0.01–BTO is more than that of NFO–BTO nanocomposites. The magnetoelectric effect was observed with a magnetocapacitance value of approximately −10% at 10 kHz in both the composites.

Photoacoustic behavior of CoFe2O4 and CoFe2O4-BaTiO3 core-shell magnetoelectric nanoparticles

Targeted drug delivery has become an increasingly popular field of research over the past decade as the desire for more discriminatory methods of treatment has risen. Photoacoustic-mediated drug delivery utilizing core-shell magnetoelectric nanocomposites has the potential to provide localized administration of medicine or even induce apoptosis via irreversible cellular electroporation. To design these systems, the suitability of specific materials must be assessed and quantified. This work reports on the photoacoustic properties found in ferromagnetic CoFe2O4 nanoparticles and magnetoelectric CoFe2O4-BaTiO3 nanocomposites, as well as the impact of core size on the photoacoustic spectra measured. The photoacoustic response of the core-shell nanocomposites was found to be significantly attenuated when compared to the pure CoFe2O4 nanoparticles. This indicates the ferroelectric BaTiO3 shell is absorbing a percentage of the generated acoustic waves, demonstrating the capability to implement these nanocomposites in a photoacoustic-mediated drug delivery system.

Applying BaTiO3-coated TiO2 core–shell nanoparticles films as scaffold layers to optimize interfaces for better-performing perovskite solar cells

In this paper, we replaced mesoporous TiO2 nanoparticles scaffold layers by BaTiO3-coated TiO2 core–shell nanoparticles films which obtained by treating pure mesoporous TiO2 layers with 1.0 wt% barium nitrate solution, successfully realized the aim of optimizing interfaces bonding at TiO2/CH3NH3PbI3. Ultrathin BaTiO3 shell layer can combine better with CH3NH3PbI3 layer so as to reduce the existence of carrier recombination centers. Moreover, better optical absorption and larger fill factor were obtained in this manner by the reason of larger CH3NH3PbI3 grain size and fewer crystal boundaries. Furthermore, photoluminescence spectra and electrochemical impedance spectroscopy verified that our core–shell scaffold material contributes to accelerate carrier separation and retard carrier recombination. As a result, average power conversion efficiency enhanced from 11.20 to 13.76% under ambient conditions, which realized almost a quarter improvement than the devices based on pure mesoporous TiO2 layers. Such results have a certain guiding effect on solving interface defects and carrier recombination.

A strategy for design of non-percolative composites with stable giant dielectric constants and high energy densities

Materials with high dielectric constants can be fabricated into electrostatic capacitors for energy storage. Traditional percolative dielectrics such as epoxy/Ag and BaTiO3/Ni have limited energy densities due to the limited breakdown strengths. Here, a strategy for design of non-percolative composites is reported having stable giant dielectric constants and high breakdown strengths simultaneously, and thus, exhibiting high energy densities. A composite is fabricated by using a core-shell type Ag@BaTiO3 fillers where the BaTiO3 shell helps to completely separate the Ag cores with other cores in a sintered BaTiO3 matrix. The composite possesses a stable giant dielectric constant (εr~51,800, εr/εm = 15.6) over wide ranges of frequencies and temperatures while retaining a small dielectric loss (tanδ < 0.02) and a high breakdown strength (Eb > 43 kV cm–1). With the giant εr and the high Eb, the composite exhibits a high energy density (Ue~4.35 J cm–3) which is much enhanced compared with that of percolative composites and neat BaTiO3. Our comparative study with existing composite models reveals that the dielectric behavior in this composite is governed by an interfacial polarization mechanism rather than the power law for percolative dielectrics. This study successfully demonstrated very high k, Eb and energy density of a BT composite by incorporating Ag@BaTiO3 core-shell fillers.

Tailoring the functional properties of PLZT-BaTiO3 composite ceramics by core-shell approach

In the present work, composite ceramics of BaTiO3 with La0.08Pb0.92Ti0.20Zr0.80O3 were prepared from powders synthesized by two different methods: (a) PLZT@BT ceramics from core-shell powders with PLZT-core and BaTiO3 shell and (b) PLZT-BT ceramic composites from mixed PLZT and BaTiO3 powders. In core-shell ceramics, a thin conductive layer of BaPbO3 was formed that resulted in an increased effective permittivity with relatively low losses (tan δ &amp;lt; 0.7 in kHz regions). The extrinsic contributions play an important role in both ceramics, but they are more evident in core-shell samples due to the large number of interfaces. These results show that novel functional properties can be tailored by the controlled chemical reaction at interfaces.

Two step synthesis and enhanced microwave absorption properties of polycrystalline BaTiO3 coated Ni nanocomposites

The core-shell Ni@BaTiO3 nanocomposites were synthesized by a facile two-step approach. The synthetic parameters on the microstructure and morphology as well as microwave absorption properties of Ni@BaTiO3 nanocomposites were investigated. High resolution transmission electron microscopy studies reveal that as-prepared Ni@BaTiO3 nanocomposites consist of the Ni nanoparticles core and polycrystalline BaTiO3 shell. The BaTiO3 coated Ni nanocomposites absorbent present significantly enhanced microwave absorption compared with the as-prepared pristine Ni nanoparticles. The optimal reflection loss (RL) of Ni@BaTiO3-parrafin composites are −42.3 dB at 10.6 GHz with an absorbent thickness of 1.88 mm and the absorption bandwidth of those below −10 dB is 6.75 GHz only with absorbent thicknesses of 1.7–2.5 mm. The RL values below −20 dB can be obtained in frequency range of 2.98–12.21 GHz for Ni@BaTiO3-parrafin composites but 7.96–14.09 GHz for Ni-paraffin composites, corresponding to absorbent layer thickness of 1.7–5.5 mm. Moreover the RL values of Ni@BaTiO3 nanocomposites absorbent exceeding −10 dB are about 1.4–3 times of those of the Ni nanoparticles absorbent at absorbent thicknesses of 1.7–5.5 mm. Furthermore, the minimum RL of Ni@BaTiO3-parrafin composite shifts to the lower frequency, compared with that of Ni-parrafin composite. These results show that microwave absorption ability of the Ni@BaTiO3 nanocomposites is superior to Ni nanoparticles and the core-shell type Ni@BaTiO3 nanocomposites are great potential microwave absorbents for practical applications.

BaTiO3 Coated CoFe2O4–Core-Shell Magnetoelectric Nanoparticles (CSMEN) Characterization

Multiferroic behavior of magnetoelectric nanoparticles exhibiting both ferromagnetic and ferroelectric properties find significance in various applications. In this study, core-shell magnetoelectric nanoparticles (CSMEN) have been fabricated by coating CoFe2O4 nanoparticles with BaTiO3 by weight using hydro-thermal method. The core-shell structure was confirmed by electron microscopy and topographic scanning probe microscopic measurements were performed for further structural analysis. While magnetic force microscopy and ferromagnetic hysteresis loop measurements substantiated ferromagnetic behavior of the core, piezo response force microscopy confirmed ferroelectric behavior and single crystalline nature of BaTiO3 shell. As analyzed by TEM diffraction pattern both core and shell are in cubic phase with their respective diffraction spots depicting their single crystalline nature.

Preparation and dielectric properties of X9R core–shell BaTiO3 ceramics coated by BiAlO3–BaTiO3

The typical “core–shell” structure in BT ceramics can easily obtain double dielectric anomalies, which greatly improve the dielectric temperature stability for multilayer ceramic capacitors. In this paper, BaTiO3 particles were coated with 0.3BiAlO3–0.7BaTiO3 shell [xBT@(0.3BA–0.7BT)] by a sol–gel method. Core–shell structure was proved to exist in ceramic grains by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). High-temperature X9R dielectrics were obtained when x=0.3 and 0.2, with a high dielectric constant (~1200) and low dielectric loss (<2.0%). Furthermore, the impedance data was fitted by an effective 4RC equivalent circuit, which could be assigned to the core, the shell, the grain boundary, and the ceramic/internal electrode interface regions. The activation energy of the core was found to decrease with x decreasing, while opposite tendency exists in the shell and the grain boundary.

Synthesis of TiN–BaTiO3 core–shell structured ceramics: A new approach to ferroelectric thin-film formation

This is the first report of the topotaxial growth of perovskite BaTiO3 on TiN by a solid-state reaction between BaCO3 and TiN. The sintering of the BaTiO3 powder in a conventional controlled-atmosphere continuous furnace is also quite unique in the sense that it mainly involves the mass transfer of BaTiO3 shell layers by diffusion. Consequently, the TiN core does not actually contribute to the sintering process, as its diffusion activity is very low. Thus, the obtained core–shell structured TiN–BaTiO3 ceramic is rather unique in having a retained TiN core that can act as a noncontact metallic electrode.

Decoration of In2O3 nanowires with BaTiO3 nanoparticles for enhancement of magnetic properties

We have fabricated the composite nanowires consisting of In2O3 core and BaTiO3 shell, via a two-step method. The BaTiO3 shell has been deposited on core In2O3 core nanowires by means of pulsed laser deposition technique. X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy were employed to analyze the structure and morphology of the products. While SEM confirmed that the products maintained the one dimensional morphology, the shell layer corresponded to the nanoparticles of the hexagonal BaTiO3 phase. With bare In2O3 nanowires exhibiting weak ferromagnetism, the ferromagnetic behavior was enhanced by decorating the In2O3 nanowires with BaTiO3 nanoparticles. The shell coating enhanced the ferromagnetic behavior at both 5 and 300 K, in terms of the increase of coercive field, remanent magnetization, and saturation magnetization values in the hysteresis curves. We suggested that the generation of BaTiO3 nanoparticles and oxygen vacancies during the high-temperature shell coating process played a role in enhancing the ferromagnetic properties of the nanowires.

Hydrothermal synthesis and properties of NiFe2O4@BaTiO3 composites with well-matched interface

NiFe2O4@BaTiO3 multiferroic composite particles were produced by a simple hydrothermal method in two steps: preparing NiFe2O4 nanoparticles and then synthesizing core-shell nanocomposites. Multiferroic composite ceramics were sintered from these powders. X-ray diffraction, Raman scattering and energy dispersive x-ray analyses indicated that the core-shell composites with a NiFe2O4 core and BaTiO3 shell were formed in the hydrothermal environment. Different types of sharp interfaces were self-assembled owing to the minimization of direct elastic energy. The saturation magnetization of the composites linearly increased with the NiFe2O4 content while the dielectric constant decreased. A dielectric peak appeared at around 460 °C because of the oxygen vacancies in the BaTiO3 ceramics. It resulted in an enhancement of magnetic permeability in the composites, indicating magnetoelectric coupling that was also observed by direct magnetoelectric measurements.