查找使用阿拉丁产品的科研文献

Atmospherically hydrothermal assisted solid-state reaction synthesis of ultrafine BaTiO3 powder with high tetragonality

Luan Saiwei,Wang Pengfei,Zhang Lei,He Yanmei,Huang Xiong,Jian Gang,Liu Cuicui,Yu Shuhui,Sun Rong,Cao Xiuhua,Fu Zhenxiao

Ultrafine ceramic powders with high tetragonality are the fundamental for the multi-layer ceramic capacitors (MLCCs). In this study, an efficient method of atmospherically hydrothermal assisted solid-state synthesis for ultrafine BaTiO 3 particles is presented. The BaTiO 3 nanopowders with homogeneous distribution, a mean particle size ~ 260 nm and high tetragonality of 1.0095 were obtained by at the optimal parameters of hydrothermal time of 6 h, Ba(OH) 2 ·8H 2 O/BaCO 3  = 0.25/0.75 and calcination temperature of 1000 o C. XRD and HRTEM analyses revealed a “core-shell” structure of TiO 2 @BaTiO 3 formed in the first-step hydrothermal process, which reduces the diffusion distance between BaCO 3 and TiO 2 , resulting in a lower calcination temperature at the second-step solid-state reaction. Compared with pure hydrothermal and solid-state reaction processes, the atmospherically hydrothermal assisted solid-state synthesis in this study shows larger ability for improving the particle size distribution and the tetragonality, reducing defects of BaTiO 3 particles. In particular, the grain size, sintering density, and dielectric constant at the Curie temperature of BaTiO 3 ceramics are 1.93 μm, 98%, and 7066, respectively. In the solid-state reaction stage, the lattice diffusion distance from BaO to TiO 2 tends to decrease due to the formation of BaTiO 3 shells, thus, high tetragonal and relatively small particle size of BaTiO 3 powder was synthesized. This work presents a method for preparing ultrafine BaTiO 3 powders with large tetragonality for MLCCs.

Defect-Modified nano-BaTiO3 as a Sonosensitizer for Rapid and High-Efficiency Sonodynamic Sterilization

Dongcai He,Weijie Wang,Nan Feng,Ziqiang Zhang,Dali Zhou,Jing Zhang,Hongrong Luo,Yunfeng Li,Xianchun Chen,Jiagang Wu

Multidrug-resistant bacteria caused by the unlimited overuse of antibiotics pose a great challenge to global health. An antibacterial method based on reactive oxygen species (ROS) is one of the effective strategies without inducing bacterial resistance. Owing to the ability of generating ROS, piezocatalytic material-mediated sonodynamic therapy (SDT) has drawn much attention. However, its major challenge is the low ROS generation efficiency in the piezocatalytic process due to the poor charge carrier concentration of piezoelectric materials. Vacancy engineering can regulate the charge density and largely promote ROS generation under ultrasound (US) irradiation. Herein, a US-responsive self-doped barium titanate with controlled oxygen vacancy (Vo) concentrations was successfully synthesized through a facile thermal reduction treatment at different temperatures (i.e., 350, 400, and 450 °C), and the corresponding samples were named as BTO-350, BTO-400, and BTO-450, respectively. Then, the effect of Vo concentrations on ROS generation efficiency during the piezocatalytic process was systematically studied. And BTO-400 was found to possess the highest piezocatalytic activity and excellent sonodynamic antibacterial performance against Escherichia coli and Staphylococcus aureus. Furthermore, its antibacterial mechanism was confirmed that the ROS generated under US could damage bacterial cell membrane and cause considerable leakage of cytoplasmic components and irreversible death of bacteria. Notably, the in vivo results illustrated that the BTO-400 could serve as an effective antibacterial agent and accelerate skin healing via SDT therapy. In all, the Vo defect-modified nano-BaTiO3 has a noticeable potential to induce a rapid and efficient sterilization as well as skin tissue repair by SDT.

Enhanced dielectric performance of P(VDF-HFP) composites filled with Ni@polydopamine@BaTiO3 nanowires

Yongchang Jiang,Jiabang Wang,Qilong Zhang,Hui Yang,Da Shen,Fuming Zhou

Dielectric polymer nanocomposites have been attracting increasing attention because of their wide range of applications in electronics industry. To improve their dielectric properties , incorporating conductive fillers and ceramic fillers into the polymer matrix is considered to be an effective solution. Here, Ni nanoparticles (about 50–90 nm) were decorated onto the surface of polydopamine (PDA) coated BaTiO 3 nanowires to synthesize Ni@polydopamine@BaTiO 3 nanowires (Ni@PDA@BT NWs, also denoted as NPB) with different Ni loading amount. The nanowires were then added into poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix and composite films were prepared. The dielectric performance of composite films is largely enhanced owing to the microcapacitor effect and interfacial polarization effect induced by Ni nanoparticles. This enhancement can be improved by increasing the loading amount of Ni. Crystallization behavior of the films were also investigated. With 20 vol% of Ni@PDA@BT NWs added, the dielectric constant of the composite film reaches 48.4 at 1 kHz, in contrast to 29.5 for 20 vol% of BT and 10.6 for pristine P(VDF-HFP). And the dielectric loss tangent remains at a low level of 0.23 at 1 kHz. These composite films exhibit potential for applications in flexible electronic devices and electrical systems.

Thermal conductivity and electrical insulation of epoxy composites with graphene-SiC nanowires and BaTiO3

Jing He,Hua Wang,Zheng Su,Yulan Guo,Xingyou Tian,Qiqi Qu,Yueh-Lung Lin

Graphene-SiC nanowires (GSiC nw ), the composite of multilayered graphene sheets and SiC nanowires, was prepared through a carbothermal reduction process. By means of incorporating SiC nanowires into multilayered graphene sheets (GS), the propagation of electron between graphene layers was effectively suppressed and the thermal conductivity was enhanced. However, the electrical conductivity of EP (Epoxy) composites was increased by one order of magnitude, which indicated that the separating effect of SiC nanowires on the electrical properties of GS was not ideal enough. Therefore, BaTiO 3 was introduced in EP composites. Experimental results revealed that the thermal conductivity of EP-BaTiO 3 composites was increased by 2.8 times (0.6434 W/m·K) with 0.092 vol% GSiC nw doping. Additionally, the electrical conductivity and the breakdown voltage of EP-BaTiO 3 composite decreased by 250.7% and 169.5% compared with neat EP, respectively. According to the thermal conductivity model, the thermal property of EP-BaTiO 3 composites with 0.6 vol% GSiC nw can reach 128 W/m·K.

Improved dielectric properties and energy density of PVDF composites using PVP engineered BaTiO3 nanoparticles

Dai Yu,Zhu Xiaojun

This work systematically investigates the effect of modifier polyvinylpyrrolidone (PVP) on the microstructure, dielectric and energy storage properties of BaTiO 3 /PVDF composites. The results demonstrate that the BaTiO 3 nanoparticles modified by PVP are uniformly dispersed in the composites, and the defects including cracks and voids are obviously decreased in contrast to the composites with unmodified BaTiO 3 nanoparticles. Due to the enhanced interfacial polarization, the composites with BaTiO 3 @PVP show improved dielectric properties compared with the composites with unmodified BaTiO 3 nanoparticles. For instance, at 1 kHz, the dielectric constant and dielectric loss of the composite with 50 vol% of BaTiO 3 @PVP nanoparticles are 80.4 and 0.085, while of which the BaTiO 3 /PVDF are 35 and 0.265, respectively. The discharge energy density of the composites is largely improved with PVP engineered BaTiO 3 nanoparticles. The composite with 30 vol% BaTiO 3 @PVP achieves a discharged energy density of 4.06 J/cc at 240 kV/mm, which is 116% larger than that of pure PVDF (1.88 J/cc). This research provides an effect modifier to prepare high performance dielectric materials.

Augmented Fluorescence Signaling on a Single BaTiO3 Microbead Optical Booster toward High-Sensitive Biosensing

Dailu Jia,Chao Lei,Wei Ren,Chenghui Liu

In this work, we report a new generation of single microbead bioassay that employs a single BaTiO3 microbead as an optical booster for target biomarker enrichment and optical enhancement toward protein and nucleic acid analysis. The single BaTiO3 microbead can not only concentrate the target molecules by nearly 104-fold but also act as an optical booster to prominently enhance the target-induced fluorescence signal by the whispering gallery mode for improving the excitation efficiency and the microlens effect for promoting the signal collecting efficiency, respectively. Compared with using a conventional single microbead, this optical booster exhibits nearly 2 orders of magnitude higher sensitivity without the assistance of any signal amplification techniques or costly instruments. Moreover, this single microbead optical booster is capable of detecting different kinds of protein and nucleic acid biomarkers in a simple mix-and-read manner, holding great potential for early clinical diagnosis.

BaTiO3 nanocrystal-mediated micro pseudo-electrochemical cells with ultrasound-driven piezotronic enhancement for polymerization

Lili Zhao,Yan Zhang,Fulei Wang,Shicong Hu,Xiaoning Wang,Baojin Ma,Hong Liu,Zhong Lin Wang,Yuanhua Sang

Conventional electrochemical polymerization is performed on electrodes driven by a direct current power source. It is impossible to realize an electrochemical polymerization reaction on the surfaces of individual nanocrystals in an aqueous system due to the difficulty of connecting all of the nanocrystals to a power source with wires or with the aid of microfabrication , especially in the environment of liquid. In this work, a micro pseudo-electrochemical polymerization reaction was proposed for in situ synthesis of polyaniline (PANI) on the surface of BaTiO 3 nanocubes to form BaTiO 3 @PANI core-shell nanocubes. The electric potential of the micro pseudo-electrochemical polymerization originates from the opposite spontaneous polarized charges on the surface of a pair of adjacent BaTiO 3 nanocubes, which form a micro-scale electrochemical cell in reaction solution. Based on the piezotronic effect of the BaTiO 3 nanocubes, ultrasonic excitation was introduced to renew the piezoelectric charges on the surfaces of the BaTiO 3 nanocubes, and enhance the polymerization reaction. The ferroelectric electric potential and piezotronic effect-induced micro pseudo-electrochemical reactions can also be used in other nanomaterials-based electrochemical applications, such as micro-electrochemical water splitting, micro-electrophotocatalysis, and ultrasonic therapy.

Dielectric properties and microstructures of Ta-doped BaTiO3–(Bi0.5Na0.5)TiO3 ceramics for X9R applications

Shen Zhengbo,Wang Xiaohui,Li Longtu

Ta-doped 0.90BaTiO 3 –0.10(Bi 0.5 Na 0.5 )TiO 3 ceramics were successfully prepared by conventional solid-state reaction method and studied to satisfy super-broad temperature stability. The effects of Ta 2 O 5 doping on the dielectric properties and microstructures were thoroughly investigated. Ta plays an important role in the formation of core–shell structure because of chemical inhomogeneity, which gives rise to the weak temperature dependence of dielectric properties. The samples with the additon of 1.5 mol% Ta 2 O 5 satisfy the X9R specification, exhibiting an optimum dielectric behavior of ε r  ~ 2100, tanδ ~ 1.6% at room temperature, which is a promising candidate material for X9R MLCC applications.

High-Energy-Density Polymer Nanocomposites Composed of Newly Structured One-Dimensional BaTiO3@Al2O3 Nanofibers

Zhongbin Pan,Lingmin Yao,Jiwei Zhai,Dezhou Fu,Bo Shen,Haitao Wang

Flexible electrostatic capacitors are potentially applicable in modern electrical and electric power systems. In this study, flexible nanocomposites containing newly structured one-dimensional (1D) BaTiO3@Al2O3 nanofibers (BT@AO NFs) and the ferroelectric polymer poly(vinylidene fluoride) (PVDF) matrix were prepared and systematically studied. The 1D BT@AO NFs, where BaTiO3 nanoparticles (BT NPs) were embedded and homogeneously dispersed into the AO nanofibers, were successfully synthesized via an improved electrospinning technique. The additional AO layer, which has moderating dielectric constant, was introduced between BT NPs and PVDF matrixes. To improve the compatibility and distributional homogeneity of the nanofiller/matrix, dopamine was coated onto the nanofiller. The results show that the energy density due to high dielectric polarization is about 10.58 J cm–3 at 420 MV m–1 and the fast charge–discharge time is 0.126 μs of 3.6 vol % BT@AO-DA NFs/PVDF nanocomposite. A finite element simulation of the electric-field and electric current density distribution revealed that the novel-structured 1D BT@AO-DA NFs significantly improved the dielectric performance of the nanocomposites. The large extractable energy density and high dielectric breakdown strength suggest the potential applications of the BT@AO-DA NFs/PVDF nanocomposite films in electrostatic capacitors and embedded devices.

Enhancement of output performance through post-poling technique on BaTiO3/PDMS-based triboelectric nanogenerator

Danish Ali,Bin Yu,Xiaochao Duan,Hao Yu,Meifang Zhu

In the modern era, the invention of new energy sources is important in order to make advances possible in electronic media. A triboelectric nanogenerator (TENG) is considered to be strong design that converts mechanical power into electrical power, using organic (polymer) or inorganic (lead, ceramic etc) materials to initiate the triboelectrification process, followed by charge separation. In this study, a lead-free BaTiO3/PDMS-Al-based TENG was fabricated by mixing tetragonal ferroelectric BaTiO3 nanocrystals in a PDMS matrix to make a composite for a working electrode film. It is worth noting that a new post- poling process has been introduced to align the dipole structures in the BaTiO3 nanocrystals, and to attain a high electron density on the surface of the working electrode film. The output was recorded up to 375 V and 6 μA of close circuit voltage and short circuit current, respectively, at a current density of 0.3 μA cm−2 and an effective power equal to 2.25 mW at a load resistance of 100 MΩ, and is four times higher than a PDMS-Al-based TENG. This study also reveals the hidden locks that will enable other inorganic materials with a dipole structure to enhance their output using the post-poling technique. The TENG has a vast field of applications due to its stability, the flexibility of its thin films and its biocompatibility. It is also an aid for exploring new TENG devices with enhanced output performance.

Dielectric properties of polystyrene based composites filled with core-shell BaTiO3/polystyrene hybrid nanoparticles

Dongrui Wang,Meiyan Huang,Jun-Wei Zha,Jun Zhao,Zhi-Min Dang,Zhongyang Cheng

Core–shell structured BaTiO3@carbon hybrid particles for polymer composites with enhanced dielectric performance

Y. Feng,W. L. Li,J. P. Wang,J. H. Yin,W. D. Fei

Core–shell structured BaTiO3@carbon (BT@C) hybrid particles were fabricated via chemical vapor deposition (CVD). Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were carried out to confirm the successful fabrication. In order to research the effect of BT@C hybrid particles on the dielectric performance of polymer composites, PVDF-HFP/BT@C composites were prepared. With the increase of the volume fraction of BT@C, the dielectric constant of composites remarkably increased. The dielectric constant of the composite with 30 vol% BT@C is 1044 at 1 kHz, which is 118 times higher than that of PVDF-HFP (8.8). The experimental results fit well with the percolation theory. The energy storage density of all composites is larger than that of pure PVDF-HFP. The influence of the carbon-shell on the dielectric properties of composites is discussed and analyzed. The enhanced dielectric properties are attributed to the increased interfacial polarization in the carbon-shell. These attractive fabrication methods of BT@C and features of PVDF-HFP/BT@C composites suggest that the method proposed herein is a new approach for developing high performance composites.