Papers by Keyword: Barium Titanate

Abstract: The development of energy storage capacitors with high dielectric constant and good stability has been focused on by researchers due to many issues regarding environmental protection and energy conservation. Barium-Strontium Titanate based ceramic capacitors are widely used for energy storage applications due to their attractive dielectric properties. In this study, (Ba_0.90Sr_0.10) TiO₃ based capacitors were produced, and the influence of additives i.e. CaZrO₃, MnCO₃, CeO₂, ZnO, and Nb₂O₅ was investigated. The parameters of all the fabrication processes have been optimized to get defect-free green and sintered samples. The defect-free green parts were sintered at 1380°C for 2 h and perovskite structure was confirmed by XRD profiles. The grain size was refined from 25 μm to 08 μm analyzed by scanning electron microscopy (SEM). The capacitor was tested at 40 KV successfully and capacitance of 2.0 nF was measured at this high voltage. The results showed that high-voltage capacitors can be fabricated with enhanced energy storage.

Abstract: Designing the fine-grained ceramics with high recoverable energy storage density and excellent mechanical performance, still presents great challenges. Because the ceramics with large pore size and low relative density were obtained by the traditional sintering method, they always exhibit small breakdown strength and poor mechanical properties, which limits the miniaturization and operation of devices in harsh environments. In this paper, we designed the barium titanate ceramics (BT) ceramics with grain size of 252 nm and relative density of 0.92 can be obtained via co-sintering of two sizes of BT particles at 1000 °C for 10 h. The cubic phase BT particles with 80 nm are doped in the tetragonal phase BT particles with 200 nm to obtain tetragonal phase fine-grained BT ceramics. When doped with 80 nm BT particles, the sintering of 200 nm BT particles is promoted. The enhanced sinterability is due to the phase transformation and metastability, which act as sintering aids. The obtained BT ceramics with nanodomains, high energy storage and mechanical properties. The discharge energy density is of 0.81 J/cm³, and the Vickers hardness is 1.75 GPa.

Abstract: The micro-nanoBaTiO₃ ceramics of different sizes have been prepared simply and controllably via a self-assembly sintering method. The effects and scopes of the application of this method in the controllable synthesis of the micro-nanoBaTiO₃ ceramics are investigated. Through the given size of BaTiO₃ powders and the combination way, the ceramics with different grain sizes, such as 400~500 nm, can be controllably synthesized. Therefore, the use of this method is conducive to the realization of the controllable synthesis of the micro-nanoBaTiO₃ ceramics.

Abstract: Barium Titanate (BT) is one of the most intriguing ferroelectric materials widely exploited both for academic and technological utilization. The study aimed to investigate characteristics of BT ceramics Synthesized by co-precipitation (BT-C) and solid-state methods (BT-S) with variation of sintering temperatures. Here, the sintering temperatures are 900°C, 1000°C, 1100°C, and 1200°C for 4 h of each The characteristics are microstructure, morphology, and dielectric properties evaluated using X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), and Inductance-Capacitance-Resistance (LCR) meter, respectively. As results, the XRD patterns shows a pure perovskite single phase of BT was obtained by solid-state method at sintering temperature of 1000°C. While, the same result was obtained by co-precipitation at sintering temperature of 1100°C. The average crystallite size of BT-C and BT-S ceramics are in close values and getting larger with the higher sintering temperatures. Meanwhile, tetragonality of the BT-C tends to be larger as compared to the BT-S. The morphology results revealed big formed particles agglomeration (>5 μm) of the BT-C ceramics and the densities proportionally increased as the higher temperatures exhibited less porosity of ceramics. Meanwhile, the BT-S grains were visible and agglomerated in a much smaller size with the density values were different as the change of the sintering temperatures. The dielectric permittivity of the BT-C and BT-S ceramics were increased with higher sintering temperature. Further, the BT-C ceramics possessed higher permittivity than the BT-S due to high densities (less porosity) of ceramics. The highest permittivity of 1150 at 40 kHz was achieved by BT-C at 1200°C.

Abstract: This paper studies how the various calcination temperatures affect the structural properties of Barium Titanate (BaTiO₃) and (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9) (BCZT) using solid-state reaction methods. BaTiO₃ and BCZT powders are calcined at various temperatures ranging from 1100°C–1300°C. Using X-ray diffraction, the phase formation, crystal structure and crystallite size of BaTiO₃ and BCZT powders were determined. The cubic crystal structure has been formed for BaTiO₃ and BCZT. At 1200°C, the reaction between BaCO₃ and TiO₂ was complete to produce BaTiO₃ composition. For BCZT composition were not fully react based on the phase structure in XRD due to impurity peak. Next, the crystallite size of BaTiO₃ powder becomes larger with increasing calcination temperature. Meanwhile, BCZT crystallite size becomes smaller when the calcination temperature is increased has discussed at the end of this paper.

Abstract: This study's goals are to fabricate and analyze the microstructure and optical properties of BT and Li-doped BT as the dependence of the Li concentrations (x) of 0.05, 0.1, and 0.15. The thin films of the BT and Li-doped BT have been successfully deposited on the quartz substrates by the sol-gel method. The microstructure and optical features were characterized via XRD and UV-Vis Spectrophotometer, respectively. The XRD patterns exhibit that the lattice parameter and cell volume of the Li-doped films are bigger than that of the BT due to the existence of Li doping in the BT host structure. Additionally, the tetragonality and crystallite size of all films decrease as the more Li number with the BLTO5 has the biggest lattice strain as compared to the others. Meanwhile, the optical characterization reveals that the transmittance spectra increase and the absorption edges shift to the shorter wavelengths as the addition of Li dopant indicating the bandgap values change. In contrast, the refractive index values of the films reduce by the more Li number.

Abstract: The paper presents the results of experimental studies of a photoactive catalyst in the form of barium titanate fibers with deposited particles of nickel, platinum and gold. Barium titanate fibers were synthesized by the molten salt method. The obtained barium titanate fibers were studied by SEM, TEM, XRD, and Raman spectroscopy. Photocatalytic studies showed that barium titanate fibers with platinum nanoparticles are the most active of the three prepared Metal/BaTiO3 samples.

Abstract: Alternating-current powder-based electroluminescence is currently the only technique for quick and easy preparation of large area, low cost electroluminescent panels by the means of material printing. Manufacturing of the panels is currently done exclusively by screen printing which is associated with deposition of much thicker layers than typical for other methods of material printing. Typical thickness of layers is in the order of tens of microns and more. The overall thickness of films forming the panel is however a serious shortcoming of the devices because the driving voltage for generation of light needs to be high and the thickness of layers render the panel non transparent from the side of the dielectric layer. One layer of dielectric films screen printed from the commercially available formulation is approximately 10 μm thick and cannot be effectively reduced anymore and thus another printing technique needs to be exploited. The goal of this work is to define and optimize a composition of a novel ink jet printing formulation of dielectric film and verification of parameters of the final layers for use in this type of technology. The major benefits of ink jet printed dielectric layer are the possible preparation of a panel emitting light from both sides with reduced driving voltage needed for its operation.

Abstract: Si₃N₄-BaTiO₃ composite ceramics, a type of high dielectric materials applied in the multifunction radome, were prepared by gas pressure-sintering method. The influences of BaTiO₃ power content on the mechanical performances, dielectric properties and microstructure of Si₃N₄-BaTiO₃ composite ceramics were investigated. The results showed that the sintering density, the elastic modulus and the flexural strength of Si₃N₄-BaTiO₃ composite ceramics all firstly increased and then decreased along with the increase of BaTiO₃ power in sample. Meanwhile, Relationship between BaTiO₃ power content and dielectric properties of Si₃N₄-BaTiO₃ composite ceramics within the frequency range of 8.2–12.4 GHz (X-band) was studied. The average of dielectric constant e of Si₃N₄-BaTiO₃ composite ceramics increased from 7.33 to 9.98 and the average of dielectric loss tand increased from 2.8 ´ 10^-3 to 0.0168 when the content of BaTiO₃ power increased from 0 to 25 wt.%. The increase of the dielectric properties of Si₃N₄–BaTiO₃ composite ceramics were attributed to the electronic and molecular polarization at interface between Si₃N₄ and BaTiO₃, compared with the pure matrix Si₃N₄.

Abstract: Sand-milling machine was firstly utilized to crush and disperse the raw materials. A homogenous and well-dispersed mixture of TiO₂ and BaCO₃ (<30nm) was obtained. The solid state reaction temperature can be reduced by 200°C for nanosized reactants compared with coarse ones. In order to increase tetragonality of nanosized BaTiO₃, an innovative two-step calcination method, which includes solid state reaction process between reactants at a low temperature T₁ and phase transition process at a high temperature T₂, was subsequently adopted. The microstructure evolution of BaTiO₃ by two-step calcination was investigated as a function of T₂ and corresponding dwelling time t₂. Pure-perovskite BaTiO₃ nanopowders with the mean particle size as small as 75nm and tetragonality (c/a ratio) higher than 1.0096 could be fabricated by two-step calcination through altering T₂ and/or its dwelling time t₂.