Dielectric Barium Titanate Research Articles

Direct Observation of Trace Elements in Barium Titanate of Multilayer Ceramic Capacitors Using Atom Probe Tomography.

Accurately controlling trace additives in dielectric barium titanate (BaTiO3) layers is important for optimizing the performance of multilayer ceramic capacitors (MLCCs). However, characterizing the spatial distribution and local concentration of the additives, which strongly influence the MLCC performance, poses a significant challenge. Atom probe tomography (APT) is an ideal technique for obtaining this information, but the extremely low electrical conductivity and piezoelectricity of BaTiO3 render its analysis with existing sample preparation approaches difficult. In this study, we developed a new APT sample preparation method involving W coating and heat treatment to investigate the trace additives in the BaTiO3 layer of MLCCs. This method enables determination of the local concentration and distribution of all trace elements in the BaTiO3 layer, including additives and undesired impurities. The developed method is expected to pave the way for the further optimization and advancement of MLCC technology.

3D‐Printed Carrageenan‐Based Nanocomposites for Force‐Sensing Applications

Technological development is leading to an exponential growth in the implementation of sensors and actuators where the concern about environmental problems is also focusing on electronic waste (e‐waste), which is composed of hazardous materials, corresponding to a large part of urban waste, and has a strong environmental impact. Therefore, more environmentally friendly electronic components are required, natural polymers being a suitable approach to solve or attenuate those problems. This work reports on a bio‐based polymer, carrageenan, embedded with dielectric barium titanate (BTO) nanoparticles to tailor the electrical response. The inclusion of the filler induces slight modifications in the thermal characteristics and on the physicochemical properties of the polymer matrix. On the other hand, the mechanical and dielectric properties improve with the addition of BTO and a high dielectric constant ofε′ ≈13 000 is obtained for the composite with 20 wt% BTO content. The increase of the dielectric constant is accompanied by a high AC electrical conductivity, leading to a high‐ε′–high‐loss material. The 20 wt% BTO composite is used to produce a force measuring sensor, due to the highest dielectric response. The functional response of the sensing system shows good stability over cycling.

High dielectric barium titanate porous scaffold for efficient Li metal cycling in anode-free cells

Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries. However, the formation of dendritic and mossy Li metal microstructures at the negative electrode during stripping/plating cycles causes electrolyte decomposition and the formation of electronically disconnected Li metal particles. Here we investigate the use of a Cu current collector coated with a high dielectric BaTiO3 porous scaffold to suppress the electrical field gradients that cause morphological inhomogeneities during Li metal stripping/plating. Applying operando solid-state nuclear magnetic resonance measurements, we demonstrate that the high dielectric BaTiO3 porous scaffold promotes dense Li deposition, improves the average plating/stripping efficiency and extends the cycling life of the cell compared to both bare Cu and to a low dielectric scaffold material (i.e., Al2O3). We report electrochemical tests in full anode-free coin cells using a LiNi0.8Co0.1Mn0.1O2-based positive electrode and a LiPF6-based electrolyte to demonstrate the cycling efficiency of the BaTiO3-coated Cu electrode.

Silane-treated BaTiO3 ceramic powders for multilayer ceramic capacitor with enhanced dielectric properties

Silane/ceramic combination provides the composites with several advantages from the advancements of new ceramic composite materials with good thermal conductivity, high mechanical and dielectric properties have wide significant applications in electrical and electronic industries. In this study, to enhance the dispersibility of dielectric barium titanate (BaTiO3) ceramic powder and additives for the fabrication of multilayer ceramic capacitors (MLCCs), surface treatment of the precursor of ceramic powder was performed using silane coupling agents. Dielectric ceramic sheets fabricated from ceramic powders that had been surface-treated with different amounts of N-[3-(trimethoxysilyl)propyl]aniline (TMSPA) which increased the surface gloss. In particular, the dielectric properties of the multilayer ceramic sheet fabricated by stacking sheets from the TMSPA-treated ceramic powder sintering at 1200 °C, it was confirmed that the dielectric constant increased from 881 to 2382 and the dielectric loss dropped from 1.96 to 1.34% with utilization of the TMSPA treatment. The physical and dielectric properties of the TMSPA-treated multilayer ceramic sheet were also determined by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, glossmetry, and electrochemical impedance analysis. The results revealed that the TMSPA-modified BaTiO3 surfaces considerably increased the dielectric property of the fabricated nanocomposite.

(BaTiO3)1‐x + (Co0.5Ni0.5Nb0.06Fe1.94O4)x nanocomposites: Structure, morphology, magnetic and dielectric properties

AbstractTwo phase‐based nanocomposites consisting of dielectric barium titanate (BaTiO3 or BTO) and magnetic spinel ferrite Co0.5Ni0.5Nb0.06Fe1.94O4 (CNNFO) have been synthesized through solid state route. Series of (BaTiO3)1‐x + (Co0.5Ni0.5Nb0.06Fe1.94O4)x nanocomposites with x content of 0.00, 0.25, 0.50, 0.75, and 1.00 were considered. The structure has been examined via X‐rays diffraction (XRD) and indicated the occurrence of both perovskite BTO and spinel CNNFO phases in various nanocomposites. A phase transition from tetragonal BTO structure to cubic structure occurs with inclusion of CNNFO phase. The average crystallites size of BTO phase decreases, whereas that for the CNNFO phase increases with increasing x in various nanocomposites. The morphological observations revealed that the porosity is highly reduced, and the connectivity between grains is enhanced with increasing x content. The optical properties have been investigated by UV−vis diffuse reflectance spectroscopy. The deduced band gap energy (Eg) value is found to reduce with increasing the content of spinel ferrite phase. The magnetic as well as the dielectric properties were also investigated. The analysis showed that CNNFO ferrite phase greatly affects the magnetic properties and dielectric response of BTO material. The obtained findings can be useful to enhance the performances of magneto‐dielectric composite‐based systems.

A reinforced, high-κ ternary polymer nanocomposite dielectrics of PVDF, barium titanate nanoparticles, and TEMPO-oxidized cellulose nanofibers

In this paper, reinforcement of dielectric nanocomposite was performed for polyvinyl fluoride (PVDF) as a matrix, which is a practical requirement for foldable and flexible electric energy devices. A fibrous nanofiller, 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCN) was employed as a nanofiller for the PVDF nanocomposite incorporating highly dielectric barium titanate nanoparticles (BT NPs). Prior to the fabrication of nanocomposite films, a chemical treatment by HCl and a surface-modification with trifluoropropyl group were applied to TOCN and BT nanoparticles, respectively. Their treatments brought about both nanofillers well-dispersed in a polar aprotic solvent for PVDF. A low percentage incorporation of the treated TOCNs up to 0.5 wt% was found to be sufficient for enhancement on the mechanical strength of nanocomposites at a high content of surface-modified BT NPs (30 vol%). The permittivity of the nanocomposites was in the range of 12 to 14 that is twice higher than that in the PVDF film. The PVDF nanocomposites at the treated TOCN loading of 0.3 to 0.5 wt% exhibited superior mechanical strength to the PVDF film. The ternary combination of PVDF, the treated TOCN, and the surface-modified BT NPs showed an improvement on tensile stiffness with maintaining the intrinsic high dielectric properties of nanocomposite films. The present nanocomposite can be a promising ternary system for an advanced design of polymer dielectrics with excellent energy storage properties.

Dielectric breakdown in epitaxial BaTiO3 thin films

In this work, thin epitaxial layers of dielectric barium titanate (BaTiO3 or BTO) were grown on Nb-doped strontium titanate (001) substrates using either molecular beam epitaxy or atomic layer deposition and then electrically stressed to the point of breakdown. The BTO layer thicknesses were in the range of 20–60 nm, and typical breakdown fields were in the range of 1.5–3.0 MV/cm. Electron microscopy and electron energy-loss spectroscopy (EELS) were used to provide information about the degradation mechanism. High-resolution imaging revealed widespread structural damage in the BTO films after breakdown had occurred, with substantial polycrystallinity as well as amorphous regions. EELS analysis of the stressed films showed characteristic signatures of valence change in the Ti L23 EELS spectra associated with the accumulation of oxygen vacancies. Stressed heterostructures that had been patterned by electron lithography showed similar trends, including degraded crystallinity as well as oxygen loss.

Fabrication and Characterization of Spin Coating Deposited Thin Film Aluminium/BaTiO3 and Pelletized Copper, MnO2/BaTiO3 Capacitor

Thin film capacitor using Aluminium (Dielectric-Barium Titanate) and pelletized Copper, MnO2 (Dielectric-BaTiO3) capacitors as substrates were constructed. The objective of this research was to develop a capacitor having high capacitance and dielectric strength. The attention was focused on the high dielectric strength of BaTiO3 and high capacitance of MnO2, so that we can develop a good capacitor. The dependence of stacked and single forms of above capacitors with respect to various electrical parameters were analysed using LCR meter. On the basis of graphs plotted for various electrical parameters such as impedance, quality factor, dissipation factor, conductance, series and parallel capacitance were analysed from the above graphs. By analysing the comparison between Aluminium (Dielectric-Barium Titanate) single and stacked forms the conclusion that I arrived was that stacked form is more preferable over single forms. Taking consideration of copper, MnO2 (Dielectric-BaTiO3) capacitor stacked forms were found to be better than single forms. Thus it was clear that the stacked form of Aluminum (Dielectric-Barium Titanate) and stacked forms of copper, MnO2 (Dielectric-BaTiO3) capacitor is more preferable while using as capacitors. Although a variety of renewable energy technologies as well as new storage devices have been developed, they have not reached wide spread use. Therefore, there is a strong need of development of improved methods for storing energy when it is available and retrieving when it is needed. The ability to store energy when it is produced is an essential waypoint on the road to turning alternative energy into regular energy. This problem of storage can be solved by supercapacitor. It is an emerging technology in the field of electrical energy storage and its use along with battery or fuel cell is viewed as a solution in many portable systems.

Artificial Asymmetric Cilia Array of Dielectric Elastomer for Cargo Transportation.

Inspired by natural ciliary movement, artificial cilia systems have recently been developed to transport microparticles and target biomolecules by the external stimuli-induced bend and twist. However, the directional transportation of cargo meets a major challenge. Here, we present an artificial asymmetric cilia array of dielectric elastomer and realize the cargo directional transportation under alternating-current (ac) electric field. Such a dielectric elastomer is composed of elastomer matrix and dielectric barium titanate (BaTiO3) nanoparticles, which can be polarized under an ac electric field and results in the swinging of artificial elastomer cilia. The asymmetry of the cilia endows themselves with the capability of asymmetric recovery stroke, which is essential for directional transportation of cargo. Transporting performance is also optimized by adjusting the applied frequencies and voltages. This study may provide a new clue to construct functional "smart" devices in electromechanical systems and biomedicine.

Influence of the synthesis method on the preparation of barium titanate nanoparticles

Dielectric barium titanate nanoparticles are essential to develop reliable microelectronic devices. However, their dielectric properties largely depend on the synthesis method used. Hence, we developed BaTiO3 nanoparticles by various synthesis methods seeking to compare and evaluate their crystal structure, size, and homogeneity. Syntheses were carried out by four distinct synthesis methods: polymeric precursor (Pechini), electrochemical, hydrothermal and microwave-assisted hydrothermal. X-ray diffraction and Raman spectroscopy analysis revealed the formation of barium titanate in cubic and tetragonal structures. The nanoparticles synthesized have BET superficial areas varying in the range 10–15m2g−1. Pechini method propitiated the formation of smaller particles than the other methods, i.e. 44.0±15nm. By the electrochemical synthesis method the particles were obtained with 67.0±20nm of diameter, with large distribution in particle size. The use of hydrothermal methods conducted to various particle size distributions; while particles of 180.0±60nm were formed using conventional hydrothermal synthesis, smaller particles (66.0±16nm) were formed using the microwave-assisted hydrothermal synthesis in lower reaction times (six fold). All four methods were effective to synthesize crystalline BaTiO3 nanoparticles, with different sizes and structural characteristics. Thus, the choice of the suitable synthesis method will depend on the desired properties of the BaTiO3 nanoparticles.

Fabrication, characterization and microwave properties of polyurethane nanocomposites reinforced with iron oxide and barium titanate nanoparticles

Polyurethane (PU) nanocomposites reinforced with magnetic iron oxide nanoparticles and/or dielectric barium titanate nanoparticles fabricated by the surface-initiated-polymerization approach were investigated. The polymer matrix incorporated with different nanoparticles shows different presenting status surrounding the nanoparticles, i.e., chemical bonding, physical entanglement and bulk polymer chain. The nanoparticles have a different effect on the thermal stability of the polymer nanocomposites. By embedding different functional nanoparticles, unique physical properties were observed, such as enlarged coercivity and larger dielectric constant (real permittivity). The synergistic effect of the binary nanoparticle reinforced PU nanocomposite was explored. The addition of the iron oxide nanoparticles does have some effect on the permittivity. However, little difference was observed in the magnetic properties and permeability after the introduction of the dielectric barium titanate nanoparticle into Fe 2O 3/PU nanocomposites. The permeability and permittivity of γ-Fe 2O 3 and BaTiO 3 nanoparticle reinforced PU nanocomposites were investigated with frequencies ranging from 10 MHz to 1 GHz. The predicted microwave properties from Bruggeman’s equation were consistent with the measured data, except for the real permittivity of Fe 2O 3/BaTiO 3/PU. The volume average method (VAM) usually used for fiber-reinforced composites with reinforcements in the thickness direction was applied in this nanocomposite system. The predicted real permittivity by VAM was found to be in better agreement with the measured data than that predicted by Bruggeman’s equation.

Barium titanate based dielectric sintered with a two-stage process

A two-stage process was employed in this study to prepare dielectric material with high relative permittivity and low sintering temperature. In the first stage, the dielectric barium titanate (BaTiO 3) powders were uniformly coated with different amounts of glass via a high temperature melting process. The glass coated powders were then mixed with different amounts of LiF and sintered at temperatures from 850 to 950 °C using different dwell times in the second stage. The addition of LiF assisted the liquid phase formation of the glass, which lowered the sintering temperature and improved the densification of the material during the sintering process. Moreover, the pre-coated glass minimized the diffusion of LiF into the BaTiO 3 powders and thus dielectric properties of the sintered dielectrics were consistent with the samples without glass and LiF additions. Very dense sintered ceramics could be obtained using this two-stage process with a low sintering temperature, ≤900 °C. The relative permittivity achieved with 2 wt.% glass and 4 wt.% LiF additions sintered at 850 °C for 60 or 120 min was higher than 1700, which was only about 15% lower than pure BaTiO 3 sintered at 1450 °C for 4 h. The dielectric loss of the sintered dielectric was less than 0.01 being somewhat higher than with the pure BaTiO 3.

Characterization of dielectric barium titanate powders prepared by homogeneous precipitation chemical reaction for embedded capacitor applications

Various articles have reported that a highly pure and uniform form of barium titanate can be prepared by homogeneous precipitation. However, most of these works emphasize the mechanism of thermal decomposition of barium titanyl oxalate tetrahydrate, and only a few have discussed morphology or particle size. The morphology and particles size of barium titanyl oxalate tetrahydrate are governed by reaction temperature, pH value and solvent ratio; the barium titanate structure can be obtained by calcinating barium titanyl oxalate tetrahydrate above 600 °C or hydrothermally in a basic solution at 200 °C. The final morphology of barium titanate in this investigation was similar to that of barium titanyl oxalate tetrahydrate and the particle size of barium titanate increased with the calcination temperature. Using this barium titanate in a polymer/ceramic composite provided better dielectric characteristics than commercial ceramic powders use in embedded capacitor applications.