BaTiO3 Particles Research Articles

Size effect of submicron barium titanate particles on dielectric properties of smectic A liquid crystal 4-nitrophenyl 4‘-decyloxy benzoate

ABSTRACTThe influence of barium titanate (BaTiO3) particles with sizes of 100, 200 and 400 nm on the dielectric properties of smectic A liquid crystal (LC) 4-nitrophenyl 4‘-decyloxy benzoate (10 NF) was investigated by low-frequency dielectric spectroscopy. It is shown that BaTiO3 particles increase the longitudinal component of the dielectric permittivity of the LC more strongly than the transversal component. In other words, the anisotropy of dielectric permittivity is increased, which is crucial for improving the performance of electro-optic effect in LC. This is the result of the coupling of the polar axis of ferroelectric particles with the director at the moment of formation of the smectic A phase from the isotropic phase. The effect is maximal for particles with a size of 200 nm, which may be related to the monodomain structure of these particles. BaTiO3 particles also affect the dielectric dispersion of LCs, which can be explained on the basis of the local field concept.

Fractal texture and dielectric properties of BaTiO3/poly-vinylidene fluoride composites

The effects of the dispersion state of BaTiO3 ceramic fillers, which significantly improve the dielectric constant of BaTiO3/polyvinylidene fluoride composites, were investigated. To understand the microscopic and macroscopic features of the obtained composite textures, we have attempted a multifractal analysis of the microstructure of composite materials. The fractal nature of the composite material texture was investigated using multifractal parameters (the qth-moment dimension D(q) and scaling exponent τq) in the formation of fractal aggregates of BaTiO3 (BT) particles in polyvinylidene fluoride (PVDF) composites. In the plots of D(q) and τ(q) vs q, the obtained results confirmed that q > 0 could be quantitatively evaluated as local characteristics (morphology, arrangement, and dispersion), whereas q < 0 could be quantitatively evaluated as global characteristics (aggregate network structure formation). As a result of evaluating the internal energies and entropies of the micro- and macro-regions from the plot of τq vs q, the aggregate formation energy (E1), aggregate network formation energy (E2), and interaction energy between the aggregates (Eint) had a relationship of E2 = E1 + Eint. The configuration entropy for the aggregate network formation (S2), particle arrangement entropy (S1), and aggregate configuration entropy (Sint) had a relationship of S2 = S1 + Sint. At q > 0, the increase in the aggregate formation energy with the amount of additive indicates the formation of particle groups. At q < 0, the generation of the interaction energy between the aggregates (Eint) suggests that the particle groups interact to form an aggregate network. Similarly, at q > 0, the increase in the arrangement entropy with the amount of additive is related to the arrangement of particles, while at q < 0, the generation of the configuration entropy (Sint) is related to the formation of the particle group network. It was clarified from the multifractal analysis that the formation of particle groups and their network structure are strongly related to the piezoelectric characteristics in this BT/PVDF system. It was revealed that the Eint and Sint obtained from the plots of D(q) and τ(q) vs q of the multifractal analysis could be related to the formation of particle groups (local interaction) and occurrence of network structure (global interaction). Therefore, the plots of D(q) and τ(q) vs q are effective means of characterizing self-organization from the fractal nature and are expected to be applied in more general research fields other than material and condensed matter.

Scalable, flexible BaTiO3/PVDF piezocomposites prepared via supersonic spraying for use in energy harvesting and integrated energy storage devices

Flexible piezoelectric nanogenerators (PENGs) are emerging as sustainable power sources for self-charging wearable electronic devices owing to their ability to harvest ambient mechanical energy. The use of piezopolymer polyvinylidene fluoride (PVDF) and piezoceramic barium titanate (BaTiO3) as flexible composite materials for PENGs deposited using the supersonic cold-spraying technique was investigated in this study. The PENG with an optimized concentration of BaTiO3 to PVDF generated a piezoelectric voltage of 11.5 V when subjected to a tapping force of 5 N for 15,000 cycles. Scanning electron microscopy images captured after cycling confirm the robustness of the BaTiO3 and PVDF composite films. A maximum power of 28.7 μW was achieved at an impedance-matching resistance of 0.7 MΩ. A flexible-PENG bending test of 3000 cycles with a bending radius of 0.8 cm confirmed the durability when an optimal PVDF matrix accommodated well-dispersed BaTiO3 particles. Furthermore, the ferroelectric characteristics of BaTiO3 and PVDF were activated by electrical poling for 14 h, thereby increasing an open circuit voltage to 37.5 V, indicating the possibility of a 3.3-times enhancement after poling.

A Coupled Electro-Mechanical Homogenization-Based Model for PVDF-Based Piezo-Composites Considering α → β Phase Transition and Interfacial Damage.

Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is a piezoelectric semi-crystalline polymer whose electro-mechanical properties may be modulated via strain-induced α → β phase transition and the incorporation of polarized inorganic particles. The present work focuses on the constitutive representation of PVDF-based piezo-composites developed within the continuum-based micromechanical framework and considering the combined effects of particle reinforcement, α → β phase transition, and debonding along the interface between the PVDF matrix and the particles under increasing deformation. The micromechanics-based model is applied to available experimental data of PVDF filled with various concentrations of barium titanate (BaTiO3) particles. After its identification and predictability verification, the model is used to provide a better understanding of the separate and synergistic effects of BaTiO3 particle reinforcement and the micromechanical deformation processes on the electro-mechanical properties of PVDF-based piezo-composites.

Preparation of High-k Polymeric Composites Based on Low-k Boron Nitride Nanosheets with High-Connectivity Lamellar Structure.

Typically, the basic method to enhance the dielectric response of polymer-based composites is to fill giant dielectric ceramic fillers, such as BaTiO3 and CaCu3Ti4O12, into the polymer matrix. Here, by using low-k boron nitride (BN) with well-controlled microstructure and surface, we successfully prepared a high-k polymeric composite, where the improvement in the dielectric constant of the composite even exceeds that of composites containing BaTiO3 and CaCu3Ti4O12 particles at the same weight percent. First, a lamellar boron nitride nanosheet (BNNS) aerogel was prepared by bidirectional freezing and freeze drying, respectively, and then the aerogel was calcined at 1000 °C to obtain the lamellar BNNS skeleton with some hydroxyl groups. Finally, the epoxy resin (EP) was vacuum impregnated into the BNNS skeleton and cured inside to prepare the lamellar-structured BNNSs/EP (LBE) composites. Interestingly, the dielectric constants of LBE with a 10 wt % BNNS content reached 8.5 at 103 Hz, which was higher by 2.7 times than that of pure EP. The experimental data and the finite element simulations suggested that the increased dielectric constants of LBE resulted from the combination of two factors, namely, the lamellar microstructure and the hydroxyl groups. The stacking of the BNNS phase into a highly connected lamellar skeleton significantly increased the internal electric field and the polarization intensity, while the introduction of hydroxyl groups on the BNNS surface further improved the polarization of the composite, resulting in a significant increase in the dielectric constant of the LBE. This work provides a new strategy for improving the dielectric constant through the microstructure design of composites.

In English

Nanocomposites containing components with semiconductor, ferroelectric, and ferromagnetic properties have attracted considerable attention of specialists due to the range of possible applications, including catalysis and electrocatalysis, electrode materials for solar and fuel cells, capacitors, electrical and biosensors, anti-corrosion coatings and much more. In recent years, both fundamental and applied interest in this direction of research is due to the possibility of creating a new type of controlled microwave devices and tools. The aim of the work is to develop methods for the synthesis of nanostructured NiCo composites based on BaTiO3 and TiO2, as well as to find the differences and regularities of their physicochemical properties. Two series of samples with different content of NiCo nanoparticles based on titanium oxide (TiO2) and barium titanate (BaTiO3) were obtained. NiCo particles were obtained by the method of chemical precipitation of nickel and cobalt carbonates in equal parts from a hydrazine hydrate solution at the temperature of 350 K. The results of X-ray phase analysis indicate the chemical purity of the obtained samples. The values of ε′, ε″ at a frequency of 9 GHz for the NiCo/BaTiO3 system are twice as high compared to NiCo/TiO2 for the corresponding values of the NiCo content, which is due to the higher values of ε′, ε″ of the initial barium titanate. Electrical conductivity of NiCo/BaTiO3 system changes by six orders of magnitude, which indicates the formation of a continuous percolation cluster of metal particles on the surface of dielectric BaTiO3 particles. The composites are heat-resistant up to 630K, as shown by the method of thermogravimetry and pronounced magnetic properties. The program for calculating frequency dependences of reflection and absorption coefficients in a complex form has been developed. EMF absorption for composites from the radiation frequency and the position of the minima of these characteristics, which agree satisfactorily with the experiment. The obtained composites can be promising components for obtaining composite systems and paints for protection against electromagnetic radiation.

BaTiO3/CeO2 heterojunction photocatalysts: design, construction and a novel application for the photocatalytic degradation of oxytetracycline hydrochloride

Abstract A polyacrylamide gel method combined with low temperature calcination technology has been developed to synthesize the BaTiO3/CeO2 heterojunction photocatalysts, which were formed by hybriding the large BaTiO3 particles and fine CeO2 nanoparticles with varied mass percent of CeO2. Various characterization methods have been used to determine the phase structure, functional group information, elemental composition, microstructure, optical and photocatalytic activity of BaTiO3/CeO2 heterojunction photocatalysts. The introduction of CeO2 into the host lattice of BaTiO3 does not change the optical band gap value (Eg = 3.20 eV) of the host lattice. As expected, the BaTiO3/CeO2 heterojunction photocatalysts exhibit highly enhanced and CeO2 composition-dependent photocatalytic activity for the degradation of oxytetracycline hydrochloride under simulated sunlight irradiation. The BaTiO3/5 wt% CeO2, BaTiO3/10 wt% CeO2, and BaTiO3/15 wt% CeO2 showed lower photocatalytic activity, while BaTiO3/20 wt% CeO2 showed highest photocatalytic activity (96.89 %) over the single component BaTiO3 and CeO2 photocatalysts with the initial oxytetracycline hydrochloride concentration, photocatalyst content and irradiation time were 100 mg/L, 1.5 g/L and 120 min, respectively. The enhanced photocatalytic activity of BaTiO3/20 wt% CeO2 heterojunction photocatalysts is ascribed to the cooperation between Ce3+ and Ce4+, improved charge transfer and separation of electron-hole pairs generated on irradiation with simulated sunlight and proper amount of surface defects or oxygen vacancies on the BaTiO3/CeO2 heterojunction photocatalysts.

Low electric field induction in BaTiO3-epoxy nanocomposites

Epoxy is widely used material, but epoxy has limitations in terms of brittleness in failure, and thus researchers explore toughening and strengthening options such as adding a second phase or using electromagnetic fields to tailor toughness and strength, on demand and nearly instantaneously. Such approach falls into the category of active toughening but has not been extensively investigated. In this research, Si-BaTiO3 nanoparticles were used to modify the electro-mechanical properties of a high-performance aerospace-grade epoxy so as to study its response to electric fields, specifically low field strengths. To promote uniform dispersion and distribution, the Si-BaTiO3 nanoparticles were functionalised with silane coupling agents and mixed in the epoxy Araldite LY1564 at different content loads (1, 5, 10 wt%), which was then associated with its curing agent Aradur 3487. Real-time measurements were conducted using Raman spectroscopy while applying electric fields to the nanocomposite specimens. The Raman data showed a consistent trend of increasing intensity and peak broadening under the increasing electric field strength and Si-BaTiO3 contents. This was attributed to the BaTiO3 particles’ dipolar displacement in the high-content nanocomposites (i.e., 5 wt% and 10 wt%). The study offers valuable insights on how electric field stimulation can actively enhance the mechanical properties in epoxy composites, specifically in relatively low fields and thin, high-aspect-ratio composite layers which would require in-situ mechanical testing equipped with electric field application, an ongoing investigation of the current research.

Dual-Mode Stretchable Sensor Array with Integrated Capacitive and Mechanoluminescent Sensor Unit for Static and Dynamic Strain Mapping

Electronic skin (e-skin) has the potential to detect large-scale strain, which is typically achieved by integrating multiple strain sensors into an array. However, the latency and limited resolution of sensing have hindered its large-scale sensing applications. Here, we have developed a high-resolution detection sensing system capable of detecting static and dynamic strain with a simple fabrication process by combining capacitive and mechanoluminescent (ML) sensor units. An elastic polydimethylsiloxane (PDMS) composite film doped with ZnS:Cu and BaTiO3(BT) particles are fabricated as the functional film of the capacitive sensor. In contrast, the transparent electrode was fabricated on the surface of the as-prepared film. By incorporating BT nanoparticles into the elastic substrate, the ML intensity of the ZnS:Cu was improved up to 2.89 times that without BT addition, and the sensitivity of the capacitive sensor was increased as well. The capacitive part of the sensor presented a GF of 0.9 and good stability, while the ML part exhibited excellent performance, making it suitable for both static and dynamic sensing. Furthermore, the strain sensor integrated by 10 × 10 sensing units is demonstrated to detect large-scale strain with high resolution. Moreover, finger joint strain distribution tracking is achieved by attaching the strain sensor unit to the finger joint. With these characteristics, the e-skin may have great potential for bio-motion monitoring and human-computer interaction applications.

Piezoelectric Nanogenerators Based On BaTiO3/PDMS Composites for High-Frequency Applications.

A series of highly flexible and environmentally friendly composites based on polydimethylsiloxane (PDMS) filled with 200 nm size ferroelectric BaTiO3 (BTO) particles at different concentrations (from 7 to 23 vol %) have been fabricated by a simple dispersion method. The dielectric, piezoelectric, and ultrasonic properties have been studied. The ferroelectric state of BTO was confirmed by differential scanning calorimetry and ultrasonic spectroscopy. The addition of BTO into PDMS strongly affects the dielectric properties of the composites. At low temperatures close to 160 K, the PDMS matrix exhibits a dielectric anomaly related to a dynamic glass transition, which shifts to higher temperatures as the BTO content increases due to the strong interaction between polymer chains and nanoparticles. Ultrasonic measurements demonstrate the appearance of a piezoelectric voltage signal on a thin plate of the composite with the highest available filler concentration (23 vol %) under longitudinal stress applied by a 10 MHz ultrasonic wave. As a result, at room temperature, the detected signal is characterized by output voltage and specific stored energy values of 10 mV and 367.3 MeV/m2, respectively, followed by a further increase with cooling to 35 mV at 150 K. The proposed BTO/PDMS composite system is thus a potential candidate for nanogenerators, namely, a simple, flexible, and lead-free device converting high-frequency (10 MHz) mechanical vibrations into electrical voltage.

Atom probe analysis of BaTiO3 enabled by metallic shielding

Atom probe tomography has been raising in prominence as a microscopy and microanalysis technique to gain sub-nanoscale information from technologically-relevant materials. However, the analysis of some functional ceramics, particularly perovskites, has remained challenging with extremely low yield and success rate. This seems particularly problematic for materials with high piezoelectric activity, which may be difficult to express at the low temperatures necessary for satisfactory atom probe analysis. Here, we demonstrate the analysis of commercial BaTiO3 particles embedded in a metallic matrix. Density-functional theory shows that a metallic coating prevents charge penetration of the electrostatic field, and thereby suppresses the associated volume change linked to the piezoelectric effect.

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

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

Enhancing Photodetection Ability of MoS2 Nanoscrolls via Interface Engineering.

Van der Waals semiconductors have been really confirmed in two-dimensional (2D) layered systems beyond the traditional limits of lattice-matching requirements. The extension of this concept to the 1D atomic level may generate intriguing physical functionalities due to its non-covalent bonding surface. However, whether the curvature of the lattice in such rolled-up structures affects their optoelectronic features or the performance of devices established on them remains an open question. Here, MoS2-based nanoscrolls were obtained by virtue of an alkaline solution-assisted method and the 0D/1D (BaTiO3/MoS2) strategy to tune their optoelectronic properties and improve the light sensing performance was explored. The capillary force generated by a drop of NaHCO3 solution could drive the delamination of nanosheets from the underlying substrate and a spontaneous rolling-up process. The package of BaTiO3 particles in MoS2 nanoscrolls has been evident by TEM image, and the optical characterizations were mirrored via micro-Raman spectroscopy and photoluminescence. These bare MoS2 nanoscrolls reveal a reduced photoresponse compared to the plane structures due to the curvature of the lattice. However, such BaTiO3/MoS2 nanoscrolls exhibit a significantly improved photodetection (Rhybrid = 73.9 A/W vs Ronly = 1.1 A/W and R2D = 1.5 A/W at 470 nm, 0.58 mW·cm-2), potentially due to the carrier extraction/injection occurring between BaTiO3 and MoS2. This study thereby provides an insight into 1D van der Waals material community and demonstrates a general approach to fabricate high-performance 1D van der Waals optoelectronic devices.

Solvothermal synthesis of nanoscale BaTiO3 in benzyl alcohol-water mixtures and effects of manganese oxide coating to enhance the PTCR effect.

A solvothermal method using various benzyl alcohol/water solvent mixtures has been used to synthesise phase pure nanocrystalline BaTiO3 samples with varying particle sizes in the range of 11-139 nm. The crystallite/particle size of BaTiO3 shows an overall decrease as the benzyl alcohol percentage increases, especially at higher percentages (≥80%) of benzyl alcohol. The decrease in crystallite/particle size can be attributed to the increased viscosity of the solvent mixture when raising the percentage of benzyl alcohol. A manganese oxide coating applied to the BaTiO3 surface had a negligible impact on its microstructure and morphology, but significantly enhanced the observed positive temperature coefficient of resistance. This research has been carried out to allow the development of smaller BaTiO3 particles for use in new battery, capacitor and thermistor technologies, whilst maintaining the PTCR property of the material that is typically observed in larger particle sizes.

Comment on “Enhancing the output performance of hybrid nanogenerators based on Al-doped BaTiO3 composite films: a self-powered utility system for portable electronics”, by B. Dudem, L. K. Bharat, H. Patnam, A. R. Mule and J. S. Yu, J. Mater. Chem. A, 2018, 6, 16101

This Comment discusses a lack of proof for the relationship of the nanogenerator performance reported in J. Mater. Chem. A, 2018, 6, 16101 to the enhanced piezoelectricity and to the Al-doping of BaTiO3 particles used as the nanogenerator core.

Large Magnetodielectric Effect of BaTiO3-BaFe12O19 Composites in a Low Magnetic Field.

A microwave sintering procedure has been developed to achieve high quality multiferroic composites of (1 - x)BaTiO3-xBaFe12O19 (x = 0.05, 0.10, 0.15, and 0.20). X-ray diffraction, scanning electron microscopy, and impedance spectra indicate that BaFe12O19 particles are isolated homogeneously by BaTiO3 particles. In a 1.8 T magnetic field, a large room temperature magnetodielectric effect over 4.3% is observed in the 0.8BaTiO3-0.2BaFe12O19 composite. The total mechanical energy dissipation (Q -1) for the BaTiO3-BaFe12O19 composites was composed of the mechanical damping of BaFe12O19, the mechanical damping of BaTiO3, and the loss at the interface. The mechanical damping of BaFe12O19 plays the dominant role in the variation of Q -1.

Biomass-based functional film integrated with nitrogen-coordinating boronic ester and cellulose-barium titanate nanohybrids

Although renewable and biodegradable biomaterials have received considerable attention as sustainable alternatives to traditional petrochemical plastics, their production and application have been limited due to insufficient mechanical properties and high hydrophilicity. In this study, we report a green and facile strategy for the preparation of a gelatin-based film with enhanced mechanical strength, water resistance, and electrochemical properties. The nitrogen-coordinating boronic ester (BN), prepared from diethanolamine and boronic acid, acted as a dynamic glue linkage. Introducing hydrophobic long-chain fatty acids of stearic acid (SA) formed a cross-linked network with BN and gelatin through bioconjugation, effectively improving the film’s water resistance. Moreover, nanofibrillated cellulose assisted the dispersion of BaTiO3 particles as a hybrid enhancement nanophase to enhance the performance of the composite film. The toughness and tensile strength of the as-prepared composites reached 22.35 MJ/m3 and 23.30 MPa, which were 424.6 % and 193.1 % higher than the neat gelatin film. Attractively, incorporating BaTiO3 nanoparticles with a high-dielectric constant endowed the film with excellent electrochemical performance. In addition, the hybrid film exhibited substantially enhanced ultraviolet-blocking properties and thermal stability. This multifunctional gelatin-based film is expected to significantly advance the industrial production and application of biomaterials in hydrogels, adhesives, and coatings.

Characterization of a Biocomposite of Electrospun PVDF Membranes with Embedded BaTiO3 Micro- and Nanoparticles

Damage to bone tissue is a common health issue that tends to increase in severity with age and other underlying conditions. To take advantage of the piezoelectric effect on bone remodulation, piezoelectric materials can be used to fill patients bone defects. Polyvinylidene fluoride (PVDF) and barium titanate (BaTiO3) are both well-known polymeric and ceramic biomaterials, respectively, as well as piezoelectric at room temperature. To mimic the extracellular matrix, PVDF membranes were produced by electrospinning onto a rotating drum to promote the alignment of fibers and micro- and nano-sized tetragonal BaTiO3 particles were embedded into these membranes to try to enhance the piezoelectric response and, therefore, bioactivity. After defining the best deposition parameters to produce pure PVDF membranes, the same parameters were carried over for the embedded membranes and both were characterized, revealing that the proposed method for obtaining β-phase PVDF (the polymer phase with highest piezoelectric coefficient) through electrospinning is viable, producing fibers with coherent diameters and alignment. The presence of barium titanate conferred bioactivity to the membranes and caused a decrease in fibers’ diameter and in superficial charge density.

Tailoring Thermal and Electrical Properties of Jeffamine Segmented Polyetherimide Composite Films Containing BaTiO3 particles.

The continuous advancement of materials science has highlighted the ongoing need for additional studies on the main composite materials topics, particularly in the field of multifunctional nano-composites, towards improving their capability to meet multifaceted requirements in order to stimulate both scientific and technological development. In this study, we report the preparation and characterization of polyetherimides (PEIs) derived from 4,4'-(4,4'-isopropylidenediphenoxy) bis (phthalic anhydride) following a two-step polycondensation reaction using either 4,4'-(1,3-phenylenedioxy) dianiline, or Jeffamine ED-600 as comonomers, or a mixture of the two diamines. Based on the PEI containing flexible Jeffamine segments, polymer composite films were developed by incorporating BaTiO3 particles. The chemical structure and morphology of the composite films were investigated by FTIR spectroscopy and scanning electron microscopy. Thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry. The influence of Jeffamine segments on the thermal decomposition process was investigated by TG/MS/FTIR measurements under air and nitrogen atmospheres. Based on the obtained data, the thermal decomposition mechanism was established and is discussed in accordance with the chemical structures of the polymers. The surface properties of the PEI and PEI-composite films were characterized by performing contact angle measurements. The addition of BaTiO3 increased the wettability of the surfaces. The dielectric characteristics of polymer composite films were investigated by broad band dielectric spectroscopy measurements. It was noticed that the addition of BaTiO3 nanoparticles to the copolymer matrix gradually enhanced the dielectric constant of the composites.

Flexoelectricity on the photovoltaic and pyroelectric effect and ferroelectric memory of 3D-printed BaTiO3/PVDF nanocomposite

Ferroelectric memories show great potential in applications of portable electronics due to low power consumption, high reliability and fast response speed. Therefore, non-destructive readout of ferroelectric memories using the ferroelectric photovoltaic effect attracted tremendous research attention. In this investigation, flexoelectric-enhanced photovoltaic effect (FPV effect) were systematically investigated in curved 3D-printed BaTiO3/PVDF composite films. In the bending process, a strain gradient field was formed between the BaTiO3 (BTO) particles, which led to a relatively large flexoelectric effect. Compared with that of pristine PVDF, the flexoelectric coefficient of BTO/PVDF-15 (15% BTO) was increased 3.7-fold to 2.65 × 10−9 C/m. Furthermore, we found that the photovoltaic current Ipv of the BTO/PVDF-15 (15% BTO) composite film increased by 3.4 times compared with the pristine PVDF film at the same curvature. This is mainly attributed to the FPV effect. In addition, “polarization channels” were found for the first time inside nanocomposite materials using the flexoelectricity effect through 2D phase-field simulations, and the channels can be artificially controlled by simply bending the film. Most importantly, the BTO/PVDF-based composite film was designed as flexible ferroelectric memories. We demonstrated for the first time that the intensity difference of the signal for 0 and 1 of the BTO/PVDF-based memories were more than 10 times, which can be read directly using a laser. This investigation shows great promise that flexoelectricity in piezoelectric polymer nanocomposite can greatly benefit the nondestructive readout of ferroelectric memory devices.