BaTiO3 Research Articles

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.

Evaluating the Efficacy of Lead-Free Piezoelectric Materials in Microcantilever Based Vibration Energy Harvesters

Abstract The piezoelectric materials have been extensively utilized in various applications, such as sensors, actuators, and energy harvesters. This study evaluates the performance of six lead-free piezoelectric materials- aluminium nitride (AlN), barium titanate (BaTiO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), polyvinylidene fluoride (PVDF), and zinc oxide (ZnO) in MEMS-based piezoelectric vibration energy harvesters (PVEHs) using cantilever configurations. Finite element analysis via COMSOL Multiphysics was employed to assess the deflection, voltage, and power outputs of these materials at their resonance frequencies, both with and without proof masses. The results indicate that BaTiO3 and PVDF cantilevers exhibited the highest voltage outputs, reaching 207.14 mV and 202.07 mV, respectively, with AlN also showing comparable performance at 184.72 mV. ZnO-based cantilevers demonstrated the highest power output of 1.35 nW without proof masses and 190.5 nW with proof masses, indicating its potential for high-power applications. The addition of proof masses generally reduced resonant frequencies but enhanced power outputs, like for ZnO. This comprehensive analysis underscores the critical impact of material selection and structural modifications on the efficiency of PVEHs, with BaTiO3, PVDF, and ZnO emerging as the most promising candidates for optimizing energy harvesting devices. This research lays a foundation for further advancements in piezoelectric MEMS technology, aiming for more efficient energy harvesting solutions.

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 (< 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.

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.

Investigation on barrier layers of Pt/BaTiO3/Pt based thin film capacitors

Barium titanate is a ferroelectric material used as a dielectric in thin film capacitors owing to its high dielectric constant. Barrier layers are utilized in these capacitors to improve the capacitors' performance. In this paper, zinc oxide and aluminium oxide are kept on both sides of BaTiO3 as barrier layers in Pt/BT/Pt capacitors and different dielectric properties are studied. The parameters such as capacitance density, leakage current, ESR, dielectric loss and dielectric strength of Pt/BT/Pt capacitors with barrier layers of different sizes are simulated using COMSOL Multiphysics modeling software. Aluminum oxide of 2 nm thickness as a barrier layer gives optimal performance. The leakage current, dielectric loss, capacitance density, equivalent series resistance and dielectric strength of Pt/BT/Pt capacitor are found to be 0.519 mA, 9.62x10‐12, 172.8 fF/µm2, 9.62 kΩ, 108 V/m respectively whereas that of Pt/ALO/BT/ALO/Pt capacitor are found to be 1.56x10‐18A, 7.81x10‐18, 11.6 fF/µm2, 9.01x1015 Ω, 5.05x109 V/m respectively. The low capacitance in Pt/ALO/BT/ALO/Pt capacitor is due to the low dielectric constant of Al2O3 layer. The reduced leakage current and increased equivalent series resistance is due to the low conductivity of the Al2O3 layer. The use of aluminium layer can reduce the electric field leading to improved dielectric strength.

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.

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.

Boosting triboelectric performance of PDMS-based nanogenerators through dual-filler embedded triboelectric layers

Triboelectric nanogenerators (TENGs) provide an effective method for harvesting mechanical energy and converting it into electrical power. Polydimethylsiloxane (PDMS)-based TENGs are particularly advantageous due to their excellent mechanical properties, high flexibility, simple manufacturing process, and low cost. In this study, we suggest a PDMS-based TENG by integrating surface-modified carbon nanotubes (SMCs) prepared by pulsed laser ablation (PLA), along with high-permittivity BaTiO3 (BTO) nanoparticles. The combination of SMCs' superior electrical conductivity and BTO's high dielectric constant has synergistically enhanced the TENG's performance. Compared to pristine PDMS-based TENGs, the TENG incorporating 0.05 wt% SMCs and 7 wt% BTO demonstrated a remarkable 200 % increase in voltage (432.44 V) and a 324 % increase in current (39.23 μA). Also, plasma treatment further boosts the triboelectric performance, achieving a voltage of 468 V, a current of 43.04 μA, and a power density of 7.83 W/m².

Multifunctional electrically switchable metalens

Here, we propose three all-solid-state, electrically switchable, transmissive, and multifunctional metalens arrays comprising tunable metal-oxide material BaTiO3 (BTO) nanopillars with different structural parameters. To produce the required phase profile for each metalens, the rectangular nanopillars, as the unit cell of the BTO structure, are developed to support arbitrary combinations of two independent phase shifts (0−2π) with bias voltage states of 0 V and 60 V, at first. Second, the structure parameters of different functional metalens arrays are generated efficiently and accurately based on the dual-phase modulation characteristics of a single structure. Finally, we use the finite-difference time-domain method to simulate the three kinds of switchable metalenses. The results show that the three metalenses can realize the function of adjustable focus position, switchable beam focusing and beam deflection, and switchable beam focusing and beam splitting.

The Introduction of a BaTiO3 Polarized Coating as an Interface Modification Strategy for Zinc-Ion Batteries: A Theoretical Study.

Aqueous zinc-ion batteries (AZIBs) have become a promising and cost-effective alternative to lithium-ion batteries due to their low cost, high energy, and high safety. However, dendrite growth, hydrogen evolution reactions (HERs), and corrosion significantly restrict the performance and scalability of AZIBs. We propose the introduction of a BaTiO3 (BTO) piezoelectric polarized coating as an interface modification strategy for ZIBs. The low surface energy of the BTO (110) crystal plane ensures its thermodynamic preference during crystal growth in experimental processes and exhibits very low reactivity toward oxidation and corrosion. Calculations of interlayer coupling mechanisms reveal a stable junction between BTO (110) and Zn (002), ensuring system stability. Furthermore, the BTO (110) coating also effectively inhibits HERs. Diffusion kinetics studies of Zn ions demonstrate that BTO effectively suppresses the dendrite growth of Zn due to its piezoelectric effect, ensuring uniform zinc deposition. Our work proposes the introduction of a piezoelectric material coating into AZIBs for interface modification, which provides an important theoretical perspective for the mechanism of inhibiting dendrite growth and side reactions in AZIBs.

Fabrication and in vitro biological properties of hydroxyapatite-sodium potassium niobate-barium titanate piezoelectric bioceramics

The utilization of piezoelectric materials in bone implants is appealing due to the inherent piezoelectric property of natural bone. The intrinsic electrical characteristics of piezoelectric biomaterials enhance antibacterial activities, biocompatibility, and bioactivity properties. This study delves into investigating the antibacterial properties, biocompatibility, and bioactivity of three-component biocomposites: sodium potassium niobate (KNN)-barium titanate (BT)-hydroxyapatite (HA). The combination of sodium potassium niobate and barium titanate, possessing suitable piezoelectric properties, with hydroxyapatite, known for its favorable biological properties, enhances the requisite properties for a bone implant. Among the various compositions studied, the combination comprising 70 wt% of the piezoelectric component (KNN-BT) and 30 wt% hydroxyapatite, labeled as 30HKB, emerged as the most optimal blend in terms of density, morphotropic phase boundary, and other biological tests conducted. Following polarization, the antibacterial efficacy of 30HKB against S. aureus bacteria cells increased by 61 %. Furthermore, the growth and adhesion of MC3T3-E1 osteoblast cells suggest enhanced biocompatibility of the 30HKB composite attributed to surface polarization. The surface charges generated by polarization facilitated the absorption of Ca2+ ions, as well as the interaction of HPO4 - and OH- ions with the precipitated Ca2+ ions, leading to the formation of the CaP layer. Hence, polarized piezoelectric ceramics exhibit heightened bioactivity compared to their non-polarized counterparts.

Active learning-based automated construction of Hamiltonian for structural phase transitions: A case study on BaTiO3.

The effective Hamiltonians have been widely applied to simulate the phase transitions in polarizable materials, with coefficients obtained by fitting to accurate first-principles calculations. However, it is tedious to generate distorted structures with symmetry constraints, in particular when high-ordered terms are considered. In this work, we implement and apply a Bayesian optimization-based approach to sample the potential energy surface, automating the Hamiltonian construction by selecting&#xD;distorted structures via active learning. Taking BaTiO3 (BTO) as an example, we demonstrate that the Hamiltonian can be obtained using fewer than 30 distorted structures. Follow-up Monte Carlo simulations can reproduce the structural phase&#xD;transition temperatures of BTO, comparable to experimental values with an error < 10%. Our approach can be straightforwardly applied on other polarizable materials and paves the way for quantitative atomistic modelling of diffusionless phase transitions.

High-Performance Flexible PLA/BTO-Based Pressure Sensor for Motion Monitoring and Human-Computer Interaction.

Flexible electronics show wide application prospects in electronic skin, health monitoring, and human-machine interfacing. As an essential part of flexible electronics, flexible pressure sensors have become a compelling subject of academic research. There is an urgent need to develop piezoelectric sensors with high sensitivity and stability. In this work, the high flexibility of polylactic acid (PLA) film and the excellent ferroelectric properties and high dielectric constant of tetragonal barium titanate (BTO) led to their use as filling materials to fabricate flexible piezoelectric composite films by spinning coating. PLA is used to produce flexible binding substrates, and BTO is added to the composite to enhance its electrical output by improving its piezoelectric performance. The peak output voltage of the PLA/BTO tetragonal piezoelectric film is 22.57 V, and the maximum short-circuit current was 3041 nA. Durability tests showed that during 40,000 s of continuous operation, in the range of 15~120 kPa, the linear relationship between pressure and the film was excellent, the sensitivity for the output voltage is 0.176 V/kPa, and the output current is 27.77 nA/kPa. The piezoelectric pressure sensor (PPS) also enables accurate motion detection, and the extensive capabilities of the PENG highlight its potential in advancing motion sensing and human-computer interactions.

A study on BaTiO3 – NiFe2O4 composite; microstructure, multiferroic and magnetodielectric properties

The lead-free x NiFe2O4 – (1-x) BaTiO3 (x = 0, 0.05, 0.1, 0.15) multiferroic composites were prepared via the solid-state sintering technique. Microstructure, multiferroic, and magnetodielectric properties of composites were investigated. According to the XRD data (from x = 5 to 15 wt%), the tetragonality factor (cT/aT) and unit cell volume of the BaTiO3 (BTO) crystal system diminished. Based on SEM images, ferromagnetic NiFe2O4 (NFO) grains are uniformly dispersed in the ferroelectric BTO matrix without additional reaction in the interfaces of two phases. The highest values of dielectric (dielectric constant (εr) ∼ 1905 and dielectric loss factor (tan δ) ∼ 0.049) and ferroelectric properties (saturation polarization (PS) ∼ 13 μC/cm2 and remnant polarization (Pr) ∼ 10 μC/cm2) are attained for x = 5 wt% due to the lowest NFO (non-ferroelectric) concentration. Also, with increasing ferrite concentration (up to 15 wt%), the ferroelectric properties of the composites show a gradual decrease. The saturation magnetization (MS) values rise due to increasing ferrite concentration (from 2 to 5 emu/g for x = 5 to 15 wt%). Moreover, coercivity (HC) drops from 150 to 110 Oe. The simultaneous observation of the ferroelectric and ferromagnetic characteristic hysteresis loops confirmed the multiferroic effect for x = 5, 10, and 15 wt%. The highest magnetodielectric constant (3 %) is obtained for x = 15 wt% multiferroic composite at the applied magnetic field of 6 kOe.

Probing ferroelectric phase transitions in barium titanate single crystals via in situ second harmonic generation microscopy

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 (BaTiO3; 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.

Exploring Structural and Optical Properties of Nanoparticles of Barium Titanate and Iron doped Barium Titanate and Their Potential Application in Antibacterial Activity

Background: Barium Titanate (BaTiO3) is a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Methods: Pure and doped Barium Titanate (BTO) nanoparticles have been synthesized by the sol-gel method. Barium hydroxide octahydrate (Ba (OH)2.8H2O) and titanium (IV) iso-propoxide (Ti {OCH[CH3]2}4) were used as starting materials. Apart from pure Barium Titanate nanoparticles, Fe-doped BaTiO3 nanoparticles of three different concentrations: 0.1, 0.2 and 0.3 in mol% were prepared and characterized using X-ray diffraction (XRD), UV visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR). Results: From the X-ray diffraction pattern, the particle size was found to be varied in a range of 17-25nm. By using UV visible spectroscopy it was observed that the band gap energy of pure BaTiO3 NP is 3.2eV. As the pure BaTiO3 nanoparticles are doped with 0.1% Fe, the band gap reduces to 3.175eV. For BaTiO3 doped with 0.2% and 0.3% Fe, the band gap energy values are 2.709 and 2.652 respectively. FTIR spectra were used to analyze the vibrational modes of BaTiO3. From the result obtained from FTIR, we can see that the absorption spectrum ranges from 450cm-1-4000cm-1. The prominent peak of pure BaTiO3 is at 500cm-1 which is due to the vibration of the Ti-O band in crystal lattice. For BaTiO3 doped with Fe2O3, the wave number of the absorption peak is shifted from 500cm-1 in pure BaTiO3. The antibacterial studies were conducted on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Conclusion: Both pure and iron-doped Barium Titanate showed significant antibacterial properties, confirming the antibacterial property of Barium Titanate nanoparticles.

Thermodynamic and dielectric properties of hexagonal barium titanate near the phase transitions

The critical behavior of the thermodynamic quantities is studied for the two phase transitions near the transition temperatures (74 K and 222 K) in the hexagonal (h) BaTiO3. A linear relationship has been established between the variations of the frequency shifts and of the dielectric constant by using the literature data in h-BaTiO3. Temperature and pressure dependence of the mode Grüneisen parameters ( γp and γT ) are also described by a power-law formula as the other thermodynamic parameters near Tpt in h-BaTiO3. Our results show that they explain the observed behavior adequately, in particular soft-mode frequency, dielectric constant, thermal expansion, the excess specific heat and the entropy near Tpt in h-BaTiO3. Temperature dependence of the isobaric mode Grüneisen parameter ( γp ), enthalpy and the Gibbs free energy, which we have evaluated, can be compared with experiments in h-BaTiO3.