BaTiO3 Research Articles

Inhomogeneity-facilitated application of ferroelectric barium titanate thin films in artificial neuromorphic system

Inhomogeneity-facilitated application of ferroelectric barium titanate thin films in artificial neuromorphic system

Superior Charge Density of Triboelectric Nanogenerator via Trap Engineering

AbstractTriboelectric nanogenerator (TENG) offers a novel approach for converting high‐entropy mechanical energy into electrical energy, yet achieving high charge density remains critical. Optimizations using dielectrics with high specific capacitance have mitigated air breakdown, but charge loss within dielectrics persists as a limiting factor. Here, based on poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) with high specific capacitance, (P(VDF‐TrFE‐CFE)) composites’ trap density and energy are engineered using high‐polarity interfaces from barium titanate (BTO) nanoparticles and dense chain segment stacking induced by electrostatic interaction with polyetherimide (PEI) to enhance charge retention capability. With modified high interfacial traps, an ultrahigh charge density of 9.23 mC m−2 is achieved in external charge excitation (ECE) TENG using 0.2 vol% PEI/P(VDF‐TrFE‐CFE) film, marking the highest charge density reported for single‐unit TENGs. This work provides novel material strategies for high‐performance TENGs, paving the way for their large‐scale practical applications.

Heterogeneous Integration of High Endurance Ferroelectric and Piezoelectric Epitaxial BaTiO3 Devices on Si

AbstractIntegrating epitaxial BaTiO3 (BTO) with Si is essential for leveraging its ferroelectric, piezoelectric, and nonlinear optical properties in microelectronics. Recently, heterogeneous integration approaches that involve growth of BTO on ideal substrates followed by transfer to a desired substrate show promise of achieving excellent device‐quality films. However, beyond simple demonstrations of the existence of ferroelectricity, robust devices with high endurance are not yet demonstrated on Si using the latter approach. Here, using a novel two‐step approach to synthesize epitaxial BTO using pulsed laser deposition on water‐soluble Sr3Al2O6 (on SrTiO3 substrates), successful integration of high‐quality BTO capacitors on Si is demonstrated, with remanent polarisation Pr = 7 µC cm−2, coercive field Ec = 150 kV cm−1, ferroelectric and electromechanical endurance of > 106 cycles. The study further addresses the challenge of cracking and disintegration of thicker films by first transferring a large area (5 mm x 5 mm) of the templated layer of BTO (≈30 nm thick) on the desired substrate, followed by the growth of high‐quality BTO on this substrate, as revealed by high‐resolution X‐ray diffraction (HRXRD) and high‐resolution scanning transmission electron microscopy (HRSTEM) measurements. These templated Si substrates offer a versatile platform for integrating any epitaxial complex oxides with diverse functionalities onto any inorganic substrate.

Enhancing Charge–Discharge Speed of Li-Ion Batteries with BaTiO3-Coated LiCoO2

Lithium-ion batteries experience a decrease in capacity as the charge–discharge speed increases. To enhance the charge–discharge speed characteristics, the surface of the LiCoO2 (LCO) cathode material was coated with ferroelectric BaTiO3 (BT) nanodots. The electric field concentration phenomenon occurs at the triple-phase interface of LCO-BT-electrolyte due to the polarizing characteristics of the ferroelectric system. BT coated on the LCO surface acts as a protective layer and promotes the insertion and extraction of Li ions, resulting in a discharge capacity of 131.9 mAh g−1 at 10 C. This value is approximately 333% higher than that of bare LCO, and it enables stable cycling of LCO even at a cut-off voltage of 4.5 V. The study’s findings suggest that coating LCO with BT nanodots can significantly improve the charge–discharge performance of lithium-ion batteries, making them more efficient for high-speed charging applications in portable electronics and electric vehicles.

Microstructural manipulation and enhanced piezo-photocatalytic performance of sol-gel-derived pure BaTiO3 particles

Eco-friendly BaTiO3 (BTO)-based materials have been intensively studied as efficient piezo-photocatalysts for the degradation of contaminants and water remediation. However, studies on pure BTO are limited due to weak light absorption, insufficient piezoelectric polarization, and poor catalytic performance. Herein, we used different liquid-phase methods to prepare pure BTO particles to enhance the piezo-photocatalytic performance through microstructural manipulation. Compared with the BTO prepared via the hydrothermal method (BTO-HT), the BTO-SG (prepared via the sol-gel method) exhibit smaller particles, larger specific surface area, greater concentration of oxygen vacancies, and larger bandgap energy, resulting in more active sites, stronger piezo-photocatalytic ability, improved degradation performance for rhodamine B (97% within 60 min) with a higher degradation rate constant (5.541 × 10-2 min-1) 7.96 times that of the BTO-HT. The catalytic performance of BTO-SG is superior to that of most previously reported BTO-based catalysts. Importantly, synergistic piezo-photocatalysis is much better than single photocatalysis (k = 0.757 × 10-2 min-1) or piezocatalysis (k = 1.703 × 10-2 min-1). In addition, the BTO-SG particles maintained stable degradation performance in environments containing inorganic anions or with various pH values. The degradation mechanism of BTO-SG was proposed in combination with free radical detection and photoelectric tests. This study provides a design thought for exploring other highly efficient BTO-based piezo-photocatalysts for water environment treatment.

Self-Powered UV Photodetectors Based on Hydrothermal Barium Titanate Film Modified With Reduced Graphene Oxide Nanolayer

Self-Powered UV Photodetectors Based on Hydrothermal Barium Titanate Film Modified With Reduced Graphene Oxide Nanolayer

Demonstration of bipolar resistive memory fabricated using an ultra-thin BaTiOx resistive switching layer with a thickness of ∼5 nm

In this study, a high-performance non-volatile bipolar resistive random-access memory (RRAM), which was fabricated using an ultra-thin barium titanate (BaTiOx, BTO) film as a resistive switching (RS) layer, was demonstrated. The BTO RS layers, whose thicknesses were only about 5 nm, were prepared using radio-frequency sputtering under different oxygen flow rates. Introduction of oxygen was used to modify the chemical compositions of the BTO films. Copper was used as the top electrode material to realize a Cu/BTO/n+-Si electrochemical metallization memory, where the resistance switching was triggered by electrochemical reaction of Cu electrode. The RRAM could repeatedly and consistently switch between a high-resistance state and a low-resistance state over 300 cycles. A large memory window of 105 and a long data retention time of >1.5 × 104 s both at room temperature and 85 °C were observed. Moreover, the Cu/BTO/n+-Si RRAM showed high switching speeds of 60–70 ns.

Unlocking Electrostrain in Plastically Deformed Barium Titanate.

Achieving substantial electrostrain alongside a large effective piezoelectric strain coefficient (d33*) in piezoelectric materials remains a formidable challenge for advanced actuator applications. Here, a straightforward approach to enhance these properties by strategically designing the domain structure and controlling the domain switching through the introduction of arrays of ordered {100}<100> dislocations is proposed. This dislocation engineering yields an intrinsic lock-in steady-state electrostrain of 0.69% at a low field of 10kVcm-1 without external stress and an output strain energy density of 5.24Jcm-3 in single-crystal BaTiO3, outperforming the benchmark piezoceramics and relaxor ferroelectric single-crystals. Additionally, applying a compression stress of 6MPa fully unlocks electrostrains exceeding 1%, yielding a remarkable d33* value over 10000pmV-1 and achieving a record-high strain energy density of 11.67Jcm-3. Optical and transmission electron microscopy, paired with laboratory and synchrotron X-ray diffraction, is employed to rationalize the observed electrostrain. Phase-field simulations further elucidate the impact of charged dislocations on domain nucleation and domain switching. These findings present an effective and sustainable strategy for developing high-performance, lead-free piezoelectric materials without the need for additional chemical elements, offering immense potential for actuator technologies.

Plasma-sprayed barium titanate cathode coatings for hydrogen evolution in electrolysis

Plasma-sprayed barium titanate cathode coatings for hydrogen evolution in electrolysis

Wearable Multifunctional Hydrogel for Oral Microenvironment Visualized Sensing Coupled with Sonodynamic Bacterial Elimination and Tooth Whitening.

Bacterial-driven dental caries and tooth discoloration are growing concerns as the most common oral health problems. Current diagnostic methods and treatment strategies hardly allow simultaneous early detection and non-invasive treatment of these oral diseases. Herein, a wearable multifunctional double network hydrogel combined with polyaniline and barium titanate (PANI@BTO) nanoparticles is developed for oral microenvironment visualized sensing and sonodynamic therapy. Due to the colorimetric properties of polyaniline, the hydrogel displays a highly sensitive and selective response for visualized sensing of oral acidic microenvironment. Meanwhile, the barium titanate in the hydrogel efficiently generates reactive oxygen species (ROS) under ultrasound irradiation, realizing non-invasive treatment in the oral cavity. Through bacterial elimination experiments and tooth whitening studies, the hydrogel can achieve the dual effect of effectively inhibiting the growth of cariogenic bacteria and degrading tooth surface pigments. Owing to the visualized sensing of the oral acidic microenvironment and efficient sonodynamic therapy function, the proposed hydrogel system offers a solution for the prevention of caries and tooth whitening, which is promising in developing the biomedical system targeting the simultaneous sensing and therapy for oral diseases.

Unveiling BaTiO3-SrTiO3 as Anodes for Highly Efficient and Stable Lithium-Ion Batteries.

Amidst the swift expansion of the electric vehicle industry, the imperative for alternative battery technologies that balance economic feasibility with sustainability has reached unprecedented importance. Herein, we utilized Perovskite-based oxide compounds barium titanate (BaTiO3) and strontium titanate (SrTiO3) nanoparticles as anode materials for lithium-ion batteries from straightforward and standard carbonate-based electrolyte with 10% fluoroethylene carbonate (FEC) additive [1M LiPF6 (1:1 EC: DEC) + 10% FEC]. SrTiO3 and BaTiO3 electrodes can deliver a high specific capacity of 80 mA h g-1 at a safe and low average working potential of ≈0.6 V vs. Li/Li+ with excellent high-rate performance with specific capacity of ~90 mA h g-1 at low current density of 20 mA g-1 and specific capacity of ~80 mA h g-1 for over 500 cycles at high current density of 100 mA g-1. Our findings pave the way for the direct utilization of perovskite-type materials as anode materials in Li-ion batteries due to their promising potential for Li+ ion storage. This investigation addresses the escalating market demands in a sustainable manner and opens avenues for the investigation of diverse perovskite oxides as advanced anodes for next-generation metal-ion batteries.

Photocurrent in Silic in Silicon/Barium Titanate/Nikel Structures

Photosensitive silicon/barium titanate/nickel structures with undoped barium titanate and doped europium were synthesized using the sol-gel method. The current-voltage characteristics were studied under illumination with a xenon lamp, highlighting a monochromatic line in the range of 400–800 nm and in dark mode. The synthesized structures showed the presence of a photocurrent on the reverse branch of the current-voltage characteristics over the entire studied range of illumination wavelengths. The maximum reverse branch current for a structure with undoped barium titanate was achieved when exposed to radiation with a wavelength of 470 nm and was about 0.6 μA for a bias voltage ranging from 2 to 10 V. Doping barium titanate with europium leads to an increase in the photocurrent by 17–26 %.

Extrinsic dielectric response due to domain wall motion in ferroelectric BaTiO[formula omitted]

BaTiO3 (BTO) is a prototypical perovskite ferroelectric, whose dielectric permittivity and loss spectra – which are strongly temperature and frequency dependent – include contributions from inhomogeneous polarization patterns, with domain walls (DWs) being the most common types. In order to elucidate how DWs influence dielectric response, we utilized a continuum approach based on the Landau–Ginzburg theory to model field-dependent properties of polydomain tetragonal phase of BTO near room temperature and above. A system with 180∘ DWs was evaluated as a case study, with both position-resolved and volume-averaged dielectric susceptibility and loss computed at different temperatures for a range of applied field frequencies and amplitudes. Our results demonstrate that cooperative dipole fluctuations in the vicinity of the DW provide a large (extrinsic) contribution to the system dielectric response relative to the intrinsic contribution stemming from within the domain. Dynamics of the DW profile fluctuations under applied field can be represented by a combination of breathing and sliding vibrational motions, with each exhibiting distinct dependence on the field frequency and amplitude. The implications of this behavior are important for understanding and improving control of coupled functional properties in ferroelectric materials, including their dielectric, electromechanical, and electrooptical responses. Furthermore, this investigation provides a computational benchmark for future studies and can be readily extended to other topological polarization patterns in ferroelectrics.

3D‐Printing of Highly Piezoelectric Barium Titanate Polymer Nanocomposites with Surface‐Modified Nanoparticles at Low Loadings

AbstractThis work describes the development and characterization of tetragonal barium titanate nanoparticles (BTO NPs) and their surface functionalization with dopamine dodecylamine (DDA), a lipophilic organic ligand. The so‐obtained lipophilic NPs (BTO‐DDA) are then formulated at low loadings (&lt; 5 wt.%) into liquid photocurable resins for vat photopolymerization (VP) and 3D printed into solid objects. The printed composites are mechanically characterized in order to assess the effect of the nanomaterial on the mechanical properties of the 3D printed polymer, revealing no significant variations in the mechanical properties (tensile or flexural) of the nanocomposites compared to the original polymer matrix. In light of these results, the printed nanocomposites are studied in terms of their capacity to generate a separation of charge by the piezoelectric effect, typical of the BTO crystal structure. This study reveals that BTO‐loaded nanocomposites display outstanding piezoelectric coefficients as high as 50 pC/N when BTO‐DDA is formulated at 3.0 wt.%, only slightly less than one‐third of the piezoelectric coefficient previously reported for bulk BTO, while preserving the mechanical properties of the polymer matrix.

Controlling the dielectric constant values of nematic liquid crystals using ferroelectric and multiferroic nanoparticles

Notably, the simultaneous manifestation of ferromagnetic and ferroelectric properties at ambient temperature has spurred significant interest in incorporating multiferroic bismuth ferrite nanoparticles (BiFeO3) into liquid crystal matrices. In this study, the parallel and perpendicular dielectric components (ε∥ and ε⊥) and dielectric anisotropy (△ε=ε∥−ε⊥) of two different nanoparticles, barium titanate (BaTiO3) and BiFeO3, doped into E7, were measured at various temperatures and frequencies. Nematic mixture E7, a widely utilized nematic liquid crystal in research and display technologies, is a eutectic mixture composed of four cyanobiphenyl derivatives i.e. 5CB, 7CB, 8OCB, and 5CT. The findings indicate a substantial reduction in dielectric anisotropy upon introducing nanoparticles into the nematic liquid crystal environment. This research highlights the significant influence of barium titanate nanoparticles, which are smaller (approximately 12 nm), on the dielectric constant. This effect was analyzed based on varying concentrations and compared to a nanoparticle with ferroic properties. Moreover, the dielectric constant can be modulated through an alternative approach. Specifically, applying an electric field during the filling process of liquid crystal cells leads to changes in the dielectric constant. These changes, observed for both nanoparticles, were particularly evident at a precise concentration of 0.1 wt%, resulting in a decreased dielectric constant.

Disentangling thermal birefringence and strain in the all-optical switching of ferroelectric polarization

Recent works have demonstrated that the optical excitation of crystalline materials with intense narrow-band infrared pulses, tailored to match the frequencies at which the crystal’s permittivity approaches close to zero, can drive a permanent reversal of magnetic and ferroelectric ordering. However, the physical mechanism that microscopically underpins this effect remains unclear, as well as the precise role of laser-induced heating and macroscopic strains. Here, we explore how infrared pulses can simultaneously give rise to strong temperature-dependent birefringence and strain in ferroelectric barium titanate. We develop a model of these two coexisting effects, allowing us to use polarization microscopy to disentangle them through their spatial distributions, temporal evolutions and spectral dependencies. We experimentally observe strain-induced patterns that are an order of magnitude larger than that which can be accounted for by laser-induced heating alone, suggesting that non-thermal effects must also play a role. Our results reveal the distinct fingerprints of heat- and strain-induced birefringence, shedding new light on the process of all-optical switching of order parameters in the epsilon-near-zero regime.

Submillisecond Electric Field Sensing with an Individual Rare-Earth Doped Ferroelectric Nanocrystal.

Understanding the dynamics of electrical signals within neuronal assemblies is crucial to unraveling complex brain functions. Despite recent advances in employing optically active nanostructures in transmembrane potential sensing, there remains room for improvement in terms of response time and sensitivity. Here, we report the development of such a nanosensor capable of detecting electric fields with a submillisecond response time at the single-particle level. We achieve this by using ferroelectric nanocrystals doped with rare-earth ions that produce upconversion (UC). When such a nanocrystal experiences a variation of surrounding electric potential, its surface charge density changes, inducing electric polarization modifications that vary, via a converse piezoelectric effect, the crystal field around the ions. The latter variation is finally converted into UC spectral changes, enabling optical detection of the electric potential. To develop such a sensor, we synthesized erbium and ytterbium-doped barium titanate crystals of ≈160 nm in size. We observed distinct changes in the UC spectrum when individual nanocrystals were subjected to an external field via a conductive atomic force microscope tip, with a response time of 100 μs. Furthermore, our sensor exhibits a remarkable sensitivity of 4.8 kV/cm/, enabling time-resolved detection of a fast-changing electric field of amplitude comparable to that generated during a neuron action potential.

High‐performance triboelectric nanogenerators boosted by synergistically aligned piezoelectric/conductive composite nanofibers

AbstractTo address the need for efficient, flexible, and wearable power sources for portable electronics, a high performance triboelectric nanogenerator (TENG) was proposed by incorporating vertically‐aligned barium titanate (BaTiO3)/antimony tin oxide (ATO) nanofibers in polydimethylsiloxane (PDMS) negative triboelectric layer, where BaTiO3 served as piezoelectric material, and ATO served as conductive filler. Silver‐coated conductive fabric was used as electrode to ensure integrability and wearability. By strategically coupling the triboelectric effect of PDMS, the piezoelectric effect of BaTiO3 nanofibers, and the charge transfer effect of ATO nanofibers, the TENG exhibited the optimum output voltage and current of approximately 119 V and 28 μA, and power density of 11.74 μW/cm2, respectively. This device demonstrates its potential applications in energy supply by effectively illuminating 174 commercial green LEDs and charging capacitors for powering electronics. Additionally, the successful integration of the TENG into a smart fencing jacket highlights its utility in practical applications.Highlights TENGs with vertically‐aligned BaTiO3/ATO composite nanofibers was constructed. The output performance of TENGs were enhanced by coupling triboelectric and piezoelectric effects. Conductive ATO nanofibers were incorporated to enhance charge transfer for performance enhancement. A smart fencing jacket with scoring system was developed using the wearable TENG.

Enhanced performance of polydimethylsiloxane-based triboelectric nanogenerator using BaTiO3/MWCNTs

Triboelectric nanogenerators (TENGs) that operate in the contact-separation mode are widely utilized for energy harvesting owing to their simple structure, excellent durability, and high energy-conversion efficiency. This study investigated the enhanced performance of TENGs using polydimethylsiloxane (PDMS) incorporating barium titanate (BTO) and multiwalled carbon nanotubes (MWCNTs). The negative triboelectric layer, comprising PDMS with BTO and MWCNTs, and aluminum foil as both the positive triboelectric layer and electrode, were optimized to improve the TENG performance. The optimal composition of PDMS incorporating 0.01 wt% MWCNTs and 10 wt% BTO yielded output voltage and current of 394.75 V and 28.24 µA, respectively. Further enhancement was realized via the application of radio frequency plasma treatment, which increased the surface roughness and fluorine incorporation. Consequently, the output voltage and current improved to 421.06 V and 32.33 µA, respectively, with a peak power density of 4.76 W/m2 at 10 MΩ. The optimized TENG maintained consistent performance over 2000 cycles and successfully illuminated commercial LEDs, thereby demonstrating its potential for practical energy-harvesting applications.

Colossal Dielectric Constant of Nanocrystalline/Amorphous Homo-Composite BaTiO3 Films Deposited via Pulsed Laser Deposition Technique.

We report the pulsed laser deposition (PLD) of nanocrystalline/amorphous homo-composite BaTiO3 (BTO) films exhibiting an unprecedented combination of a colossal dielectric constant (εr) and extremely low dielectric loss (tan δ). By varying the substrate deposition temperature (Td) over a wide range (300-800 °C), we identified Td = 550 °C as the optimal temperature for growing BTO films with an εr as high as ~3060 and a tan δ as low as 0.04 (at 20 kHz). High-resolution transmission electron microscopy revealed that the PLD-BTO films consist of BTO nanocrystals (~20-30 nm size) embedded within an otherwise amorphous BTO matrix. The impressive dielectric behavior is attributed to the combination of highly crystallized small BTO nanograins, which amplify interfacial polarization, and the surrounding amorphous matrix, which effectively isolates the nanograins from charge carrier transport. Our findings could facilitate the development of next-generation integrated dielectric devices.