BaTiO3 Nanowires Research Articles

Formation mechanism of BaTiO3 nanowire through heterogeneous nucleation using K2Ti4O9 as template

This work demonstrates a mechanism of heterogeneous nucleation for the synthesis of BaTiO3 nanowires utilizing K2Ti4O9 as template by manipulating alkalinity, temperature and reaction time. Results suggest that the synthesis of BaTiO3 does not occur through a hydrothermal ion-exchange, instead, the predominant mechanism observed is the heterogeneous of dissolution-crystallization. The consistency of crystallographic orientation for BaTiO3 nanowires is affected by the hydrothermal conditions. BaTiO3 nanowires synthesized at 190 °C/0.2 M exhibit a uniform (100)/(001) crystallographic orientation, albeit not consistently along the length of the nanowires, while BaTiO3 crystal grains no longer have the same crystallographic orientation at 190 °C/0.8 M. By investigating the reaction mechanism of BaTiO3, this work may have great significance for the synthesis of perovskite-type MTiO3 (M = Ba,Ca, Sr, Pb) utilizing layered titanates.

Ultrahigh energy density in dielectric nanocomposites by modulating nanofiller orientation and polymer crystallization behavior

High-energy density dielectrics for electrostatic capacitors are in urgent demand for advanced electronics and electrical power systems. Poly(vinylidene fluoride) (PVDF) based nanocomposites have attracted remarkable attention by intrinsic high polarization, flexibility, low density, and outstanding processability. However, it is still challenging to achieve significant improvement in energy density due to the common contradictions between electric polarization and breakdown strength. Here, we proposed a novel facile strategy that simultaneously achieves the construction of in-plane oriented BaTiO3 nanowires and crystallization modulation of PVDF matrix via an in-situ uniaxial stretch process. The polar phase transition and enhanced Young's modulus facilitate the synergetic improvement of electric polarization and voltage endurance capability for PVDF matrix. Additionally, the aligned distribution of nanowires could reduce the contact probability of nanowire tips, thus alleviating electric field concentration and hindering the conductive path. Finally, a record high energy density of 38.3 ​J/cm3 and 40.9 ​J/cm3 are achieved for single layer and optimized sandwich-structured nanocomposite, respectively. This work provides a unique structural design and universal method for dielectric nanocomposites with ultrahigh energy density, which presents a promising prospect of practical application for modern energy storage systems.

Hydrothermal synthesis and morphology control mechanism of BaTiO3 from NaTi3O6(OH)(H2O)2 precursors

We present a study on the hydrothermal synthesis of BaTiO3 utilizing NaTi3O6(OH)- (H2O)2 nanowires, which was conducted by controlling temperature, alkalinity and time. Initially, increased temperature has promoted the synthesis of BaTiO3 and induce a change in the morphology. When the temperature increases within the range of 90 °C–210 °C, the morphology of the product transitions from nanoparticle to spindle-shaped to nanowires. Then, a time-dependent experiment was conducted to investigate the mechanisms involved in the transformation of the morphology. The formation of nanoparticle occurs through the process of dissolution-crystallization, while the formation of BaTiO3 nanowires is attributed to hydrothermal ion exchange. Also, the hydrothermal process is characterized by grain aggregation and grain growth. By investigating the synthesis and morphology evolution of BaTiO3, this work holds significant potential for the synthesis of BaTiO3 nanowires or other perovskite-type MTiO3 employing titanate as a precursor.

Design and preparation of ternary polymer nanocomposites for high energy density film capacitors

High discharge energy density (Ue) film capacitors are important for miniaturization and integration in power electronic applications. The Ue of a polymer film is mainly dependent on Weibull's breakdown strength (Eb) and dielectric constant (εr). This work aims to develop ternary nanocomposites composed of polycarbonate (PC), Al2O3 nanoparticles (Al2O3 NPs) and BaTiO3 nanowires (BT NWs) for capacitive energy-storage. Al2O3 NPs have a wide bandgap and are expected to enhance Eb owing to their insulating nature, while BaTiO3 nanowires (BT NWs) are ferroelectric and are expected to provide a high εr. To overcome local electric-field distortion at the interface due to the mismatch in εr, core-shell structured BT@SiO2 NWs are prepared. The Eb of the composite containing 1.0 wt% Al2O3 NPs and 6.0 wt% BT@SiO2 NWs can reach 626 MV/m while that of the pure PC is 465 MV/m. As a result, its Ue reaches 12.12 J/cm3, which is improved by 211% that of the pure PC. Its discharge efficiency is 83.5%. A finite element analysis corroborates the superiority of the ternary polymer nanocomposites for dielectric energy-storage.

Sonophotocatalytic water splitting by BaTiO3@SrTiO3 core shell nanowires

Sonophotocatalysis has garnered significant attention due to its potential to enhance advanced oxidation processes, particularly water splitting, by employing materials with combined sonocatalytic and photocatalytic properties. In this study, we synthesized and investigated core–shell BaTiO3@SrTiO3 nanowires (BST NWs) with varying Sr/Ba molar ratios (2.5:7.5, 5.0:5.0, 7.5:2.5 mM, denoted as BST-1, BST-2, and BST-3, respectively) as catalysts for hydrogen production through water splitting. The piezoelectric nanowires demonstrated hydrogen evolution via both sonocatalysis and photocatalysis. In the sonophotocatalysis process, the ultrasonic vibration induced mechanical forces on the BST nanowires, thereby establishing a built-in electric field. This built-in electric field facilitated the effective separation of photo-generated charge carriers and prolonged their lifetimes, leading to a synergistic enhancement of hydrogen evolution. The pristine BaTiO3 and SrTiO3 nanowires exhibited relatively low hydrogen evolution rates (HER) of 7.0 and 6.0 µmol·g−1min−1, respectively. In contrast, the core–shell nanowires exhibited a substantial improvement in the hydrogen evolution rate. The HER increased with the addition of Sr, and BST-1, BST-2, and BST-3 achieved HERs of 12.0, 13.5, and 18.0 µmol·g−1min−1, respectively. The superior performance of BST-3 nanowires can be attributed to their highest piezoelectric potential and largest surface area. Additionally, BST-3 nanowires demonstrated remarkable stability over multiple cycles, validating their practical applicability as efficient photocatalysts.

Composition-driven morphological evolution of BaTiO3 nanowires for efficient piezocatalytic hydrogen production

Hydrogen production from water by piezocatalysis is very attractive owing to its high energy efficiency and novelty. BaTiO3, a highly piezoelectric material, is particularly suitable for this application due to its high piezoelectric potential, non-toxic nature, and physicochemical stability. Owing to the critical role of morphology on properties, one-dimensional (1D) materials are expected to exhibit superior water-splitting performance and thus there is a need to optimise the processing conditions to develop outstanding piezocatalysts. In the present work, piezoelectric BaTiO3 nanowires (NWs) were hydrothermally synthesised with precursor Ba:Ti molar ratios of 1:1, 2:1, and 4:1. The morphology, defect chemistry, and hydrogen evolution reaction (HER) efficiency of the as-synthesised BaTiO3 NWs were systematically investigated. The results showed that the morphological features, aspect ratio, structural stability and defect contents of the 1D morphologies collectively have a significant impact on the HER efficiency. The morphological evolution mechanism of the 1D structures were described in terms of ion exchange and dissolution-growth processes of template-grown BaTiO3 NWs for different Ba:Ti molar ratios. Notably, the BaTiO3 NWs synthesised with Ba:Ti molar ratio of 2:1 displayed high crystallinity, good defect concentrations, and good structural integrity under ultrasonication, resulting in an outstanding HER efficiency of 149.24 μmol h−1g−1 which is the highest obtained for nanowire morphologies. These results highlight the importance of synthesis conditions for BaTiO3 NWs for generating excellent piezocatalytic water splitting performance. Additionally, post-ultrasonication tested BaTiO3 NWs demonstrated unexpected photocatalytic activity, with the BTO-1 sample (1:1 Ba:Ti) exhibiting 56% photodegradation of RhB in 2 h of UV irradiation.

Intrinsically morphological effect of perovskite BaTiO3 boosting piezocatalytic uranium extraction efficiency and mechanism investigation

Developing a convenient, efficient and eco-friendly approach for the recovery of U(VI) ion is a key measure to solve the environmental problems arising from the utilization of nuclear energy. Herein, the high efficiency of uranium extraction is realized by the piezo property of perovskite BaTiO3, revealing the intrinsically morphological engineering effect on the piezocatalytic performance. Especially, BaTiO3 nanowires (BTO NWs) exhibit not only an excellent piezocatalytic activity with U(VI) extraction rate of 96.8% in a UO2(NO3)2 aqueous solution compared to 71.3% of BaTiO3 nanoparticles (BTO NPs), but also a promising piezocatalyst for U extraction in a real U-mining wastewater with various pH ranges. Piezo response force microscopy and finite elemental simulation show that the piezo response of BTO NWs is much higher than BTO NPs. Additionally, some factors (pH, various ions, different powers) are explored on piezocatalytic efficiency for U(VI) extraction. The results from electron spin resonance and the charge/radical capture experiments confirm that the active species (e-, •O2-, •OH) stemmed from the piezo induction of BTO NWs and BTO NPs in the piezocatalytic U(VI) reduction process. The present work reveals the structure-performance correlation during piezocatalysis and highlights the crucial role of piezocatalysis in dealing with environmental problems.

Flexible and highly piezoelectric nanofibers with organic–inorganic coaxial structure for self-powered physiological multimodal sensing

The relatively low sensitivity of flexible piezoelectric nanogenerators (PENG) is the most urgent problem to be solved for their applications in internet of things and artificial intelligences. To improve the piezoelectricity of polymeric fibers without discount of flexibility, BaTiO3 nanowire (BTNW) with high aspect ratio is introduced into the piezoelectric P(VDF-TrFE) (denoted as PT) electrospun fibers to form coaxial composite nanofibers for improving the sensitivity towards external mechanical loads. To reinforce the organic–inorganic interfacial interaction for the improvement of the piezoelectric response, a nanolayer of polydopamine (PDA) is uniformly coated on the surface of BTNW (denoted as pBTNW) to form PT/pBTNW nanofibers. The introduction of 7 wt% pBTNW into the fibers significantly improves the polymeric β-phase conformation and mechanical properties, simultaneously, resulting in an optimal piezoelectric output of 18.2 V under an impact force of 5 N with excellent sensitivity of 4.3 V N−1. Through both theoretical simulation and experimental characterization, the PT/pBTNW-based PENG exhibits a higher electrical output than the equivalent nanoparticle-based PENG. The optimized PENG sensor can be used for self-powered and sensitive biomonitoring of physiological movements, finger identification and voice recognition. Overall, this work offers a reliable method for enhancing piezoelectricity of flexible polymeric nanofiber and designing high-performance PENG for wearable fabric-based sensors.

Assembly of highly-sensitive capacitive flexible pressure sensor based on BTO NWs -TPU porous composites film

In this paper, an effective strategy for fabricating high-sensitive flexible capacitive pressure sensors is proposed. By combining the BaTiO3 nanowires (BTO NWs), which have an ultra-high aspect ratio, with thermoplastic polyurethane (TPU), a flexible porous dielectric layer is constructed for the construction of a high-sensitive capacitive pressure sensor, and the sensor's sensing performance was also explored deeply. Results show that the functionalized BTO NWs uniformly disperse in the polymer matrix, which can be beneficial to increasing the permittivity of the composites, thus enhancing the performance of the capacitive pressure sensor. The fabricated porous BTO-TPU capacitive pressure sensor exhibits a high sensitivity (∼1.47 kPa−1) at the pressure range of 0–10 kPa, fast response (∼86 ms), and excellent durability under 10,000 cycles, suggesting that the porous dielectric helps to improve the capacitance variation of the device. Furthermore, the sensing behavior of the sensor is verified for human activities monitoring by attaching the sensor to the joints of the human. In addition, this work also reveals the expansive application prospect of BTO NWs in flexible wearable electronics.

Polyimide/BaTiO3/NiNWs composites with enhanced dielectric properties

High dielectric constant and low dielectric loss are the target researchers strive to achieve simultaneously. In this work, BaTiO3 and nickel nanowires (NiNWs) were dispersed in polyimide (PI) by solution blending and magnetic field orientation. The NiNWs interspersed between BaTiO3 and insulating PI matrix provide polarization centers and heterojunctions, which can effectively improve the dielectric constant and inhibit the generation of conductive paths. In addition, this work also investigated the effect of magnetic field induced NiNWs orientation, such as parallel orientation and vertical orientation, on the dielectric properties. It was suggested that vertical orientated NiNWs could increase dielectric constant and suppress dielectric loss due to the vertical oriented NiNWs.

PVDF-based matrix with covalent bonded BaTiO3 nanowires enabled ultrahigh energy density and dielectric properties

The covalent bonded cross-linked inorganic-polymer nanocomposites were designed by using high-k amine modified BaTiO3 nanowire (NH2-BTNW) and ferroelectric poly(vinylidene fluoride-co-hexafluoropropylene)-graft-poly(glycid methacrylate) (V-H-G). Compared with the fluoropolymer and physical mixed nanocomposite, increased dielectric constant, suppressed dielectric loss, and elevated breakdown strength were achieved for NH2-BTNW/V-H-G due to the formation of trapping centers arising from the networks and improved dispersity of nanofiller in the matrix. The optimal sample of 15-NH2-BTNW/V-H-G (15 wt% nanofiller loading) displayed ultrahigh energy density of 20.78 J/cm3 at the breakdown strength of 580 MV/m. This covalent bonded cross-linked inorganic-polymer nanocomposite would provide alternative strategy to design high performance dielectric materials.

Covalently modified and hierarchically structured corn-like BNNs@BT/benzoxazole composites with enhanced dielectric properties over an ultra-wide temperature range

Polymer dielectric material is widely used in pulsed power technology and high-energy weapon systems. However, enhanced dielectric constant of polymer is accompanied by suppressed breakdown strength with the addition of dielectric ceramic. Herein, we report an efficient method to prepare functional corn-like hybrids which consist of BaTiO3 nanowires (BT) and BNNs nanosheets based on surface modification and high temperature ceramization. It is demonstrated that the outer BNNs not only optimizes the intrinsic dielectric difference matching, but also effectively suppress the loss caused by carrier migration. Especially, an increasement for operating temperature is achieved with the help of the poly-p-phenylene benzobisoxazole (PBO). Under 4 wt% filling, the composites have the highest discharged energy density (Ud = 2.24 J cm−3). Meanwhile, it also has high charge and discharge efficiency (η = 85 %) and an ultra-wide temperature dielectric stability (25 ℃-200 ℃). This work provides a promising dielectric nanocomposite candidate for high temperatures applications.

Bilayer structured PVDF-based composites via integrating BaTiO3 nanowire arrays and BN nanosheets for high energy density capacitors

Polymer based dielectric nanocomposites with high energy density are highly desirable to satisfy the lightweight and integration of electrostatic capacitors in electronic and electrical equipment. Recently, it is proved that polymer incorporated with aligned nanowire array represents an effective strategy for significantly improving the permittivity due to largely enhanced space charge and orientation polarization. Nevertheless, it is still a great challenge to overcome the contradictory relationship between permittivity and electric breakdown strength. In this work, a unique spatial design in bilayer structured PVDF based nanocomposites are proposed by incorporating BaTiO3 nanowire array with high-permittivity and BN nanosheets with wide-band gap, respectively. The bottom BaTiO3/PVDF layer and upper BN/PVDF layer are constructed for the synergy ascension of permittivity and breakdown strength by the optimization of BN nanosheet content. As a consequence, the dielectric permittivity of BaTiO3/BN-PVDF nanocomposite reaches 35.3 at 1 kHz, which is higher than that of 33.9 for BaTiO3/PVDF nanocomposite and 9.1 for pristine PVDF film, respectively. Also, the significantly increased electric displacement, e.g., 12.1 μC cm−2, enhanced Eb, e.g., 500.3 kV mm−1 and suppressed leakage current density are obtained in BaTiO3/BN-PVDF nanocomposites. The highest discharged energy density reaches 16.1 J cm−3, which shows a great improvement comparing to that of commercial biaxially oriented polypropylene (BOPP) film. This work demonstrates a unique design of spatial structure integrating various anisotropic nanofillers in polymer-based nanocomposite, whose outstanding energy storage performance makes it as a promising candidate for high-performance electrostatic capacitors application.

Remarkably enhanced piezo-photocatalytic performance in BaTiO3/CuO heterostructures for organic pollutant degradation

Introducing polarization field of piezoelectric materials is an effective strategy to improve photocatalytic performance. In this study, a new type of BaTiO3/CuO heterostructure catalyst was designed and synthesized to achieve high piezo-photocatalytic activity through the synergy of heterojunction and piezoelectric effect. The BaTiO3/CuO heterostructure shows a significantly enhanced piezo-photocatalytic degradation efficiency of organic pollutants compared with the individual BaTiO3 nanowires (NWs) and CuO nanoparticles (NPs). Under the co-excitation of ultrasonic vibration and ultraviolet radiation, the optimal degradation reaction rate constant k of polarized BaTiO3/CuO heterostructure on methyl orange (MO) dye can reach 0.05 min−1, which is 6.1 times of photocatalytic rate and 7 times of piezocatalytic rate. The BaTiO3/CuO heterostructure with remarkable piezo-photocatalytic behavior provides a promising strategy for the development of high-efficiency catalysts for wastewater purification, and it also helps understand the coupling mechanism between piezoelectric effect and photocatalysis.

An ultra-high aspect ratio BTO nanowires synthesized via slowing the release of barium ions

Normally, the synthesis of the BaTiO3 nanowires is via the ion exchange of K2Ti8O17 nanowires with Ba2+ under hydrothermal conditions. The concentration of the Ba2+ should be maintained at a low concentration to slow the ion exchange for preventing the crush of templates, thus reducing the quality and yield of the nanowires. In this paper, insoluble barium salt, that is, barium carbonate (BaCO3) powder was used as a Ba2+ sustained release agent, which can release a sufficient amount of Ba2+ and keep the low concentration of Ba2+ for ion exchange. The BaTiO3 nanowires with an ultra-high aspect ratio were prepared by this strategy. Thereafter, XRD, SEM, etc. Were used to characterize the as-obtained samples. Results showed that the obtained nanowires possess an average diameter of 11.6 nm and length up to several microns. Compared with other easily soluble barium salts, BaCO3 can reduce the cation exchange rate and increase the nucleation and growth of BaTiO3 nanowires. Additionally, reliable and reproducible experimental phenomenon showed that the above method has obvious advantages in large-scale production and high consistency, which provides an essential strategy for the application of BaTiO3 nanowires in flexible electronic devices, especially in capacitive sensors, film-type capacitors, and energy-storage devices.

High-temperature PMIA dielectric composites with enhanced thermal conductivity utilizing functionalized BaTiO3 nanowires–carbon nanotubes fillers

This study reports that a novel high-temperature poly (m-phenyleneisophthalamide) (PMIA) composite with enhanced dielectric constant and thermal conductivity was prepared by filling with BaTiO3 nanowires–carbon nanotubes (BTCNs) fillers. Due to effective functionalization of BaTiO3 nanowires (BTNWs) and multi-wall carbon nanotubes (MWCNTs), the fabricated BTCNs fillers were homogeneously dispersed in PMIA matrix. The consequence displays that the dielectric constant of PMIA composite with 15 wt % BTNWs fillers increases to 27.6 at 103 Hz, which is about nine times higher than that of pure PMIA. Moreover, owing to the high thermal conductivity of MWCNTs, the thermal conductivity of PMIA with 15 wt% BTNWs fillers increases to 1.01 W/(mK). The enhanced thermal conductivity is beneficial for BTCNs/PMIA composite to dissipate the generated heat by dielectric loss. Considering these merits, this research would provide new methods and ideas for preparation of high-temperature dielectric polymer composites and reducing the internal thermal effect.

Composite of aromatic polythiourea/BaTiO3 nanowires with high energy density and high discharge efficiency for energy storage applications

Ceramic/polymer nanocomposites have shown great potential in high energy storage density capacitors for pulsed power applications. However, due to the difference in surface energy between inorganic fillers and polymers, the discharge energy density and efficiency of nanocomposites are limited. In this article, the BaTiO3 (BT) nanowires (NWs) modified with dopamine (Dopa) was introduced into aromatic polythiourea (ArPTU) polymer matrix as composite for high-performance dielectrics. This is a new path about the introduction of a high dielectric constant ceramic into high dipole moment linear polymers (HDMLP), which produces the polymer composite with high energy storage density and high discharge efficiency. The composite ArPTU/BT NWs shows an energy density of 7.5 J cm−3 and high efficiency more than 90% is obtained under an electric field of 250 MV m−1. It also has been found that the modification of BT NWs with the Dopa reduces the dielectric loss of composite effectively due to the good synergistic effective between ArPTU and BT NWs, and high stability of composite for energy storage is also achieved. This work provides an effective solution for achieving high energy storage density and high discharge efficiency in polymer dielectrics for practical capacitor applications.

High Energy Storage Performance of PMMA Nanocomposites Utilizing Hierarchically Structured Nanowires Based on Interface Engineering.

To overcome the inherent high hysteresis loss of ferroelectric polymer-based nanocomposites, non-ferroelectric linear dielectric poly(methyl methacrylate) (PMMA) is adopted as the polymer matrix for high discharge efficiency. At the same time, slender ferroelectric BaTiO3 nanowires (BT NWs) with a high dielectric constant are selected as the nanofiller for high energy density. To avoid the agglomeration of BT NWs and enhance the strength of interfaces, dopamine is used as organic coatings to tailor the interface. The BT@dopa NWs/PMMA nanocomposites exhibit excellent interface compatibility between the BT NWs and PMMA matrix and a very good microstructure uniformity. Based on this, hierarchically structured BT@SiO2@dopa NWs are designed and prepared to overcome the uneven electric field distribution at the interface, resulting from the dielectric constant mismatch. The discharged energy density (Ue) can be largely enhanced from 3.76 J/cm3 for pure PMMA films to 11.78 J/cm3 for PMMA-based nanocomposites by incorporating 5.0 wt % BT@SiO2@dopa NWs. In addition, a high discharging efficiency (η) of 91% is obtained simultaneously in the nanocomposites. Both experimental and theoretical simulations demonstrate that the double core-shell structure nanowire fillers can effectively alleviate the local field distortion, inhibit leakage current, and suppress remnant electric displacement, leading to the high Ue and η. These findings are significant in facilitating the development of high-performance film dielectric capacitor materials using PMMA-based nanocomposites toward high energy storage density.

Strontium Barium Titanates Nanowires Sensors: Preparation and Application in Prediction of Cancers by Exhaled Biomarkers

Sr0.6Ba0.4TiO3, SrTiO3, BaTiO3 nanowires were synthesized by hydrothermal method with all-inorganic raw materials and without any pH adjustment, organic precursors or templates, high temperature. The width of nanowires is 25-150 nm, the length is ten to hundred of micrometers. The array of sensors based on Sr0.6Ba0.4TiO3, SrTiO3 and BaTiO3 nanowires was designed without any organic modifier.

Effect of BaTiO3 nanowire on effective permittivity of the PVDF composites

With the increasing application of barium titanate (BaTiO3) in polyvinylidene fluoride (PVDF), the evaluation of its dielectric properties has attracted the attention of many frontier scholars. In this paper, from the theoretical point of view, the effects of the aspect ratio and the concentrations of BaTiO3 nanowires on macroscopic dielectric properties were studied by the finite element method. Depending on the calculation results, some conclusions had been obtained: First, it was found that the effect of higher aspect ratios of nanowires on the effective permittivity of the composites was not significant when the aspect ratio of the nanowire filler exceeded 20. Second, when the permittivity of the BaTiO3 nanowires reaches about 3000, as the permittivity of the filler increases, the rate of change of the effective permittivity of the composite material gradually slows down, which indicates that nanowires with higher permittivity have little influence on the effective permittivity of the composites. Finally, by comparing with permittivity data of BT/PVDF composites in the literature, it was found that the simulation results have good consistency with the experimentally measured values. The above-mentioned results have shown that the composite may exhibit good dielectric properties at a low concentration (<30 vol. %) and low permittivity filler. Moreover, the electrostatic field can roughly represent the electric field of a low-concentration composite under a certain electric field strength.