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Sol-Gel Synthesis and Characterization of Ba1-xGdxTiO3+δ Thin Films on SiO2/Si Substrates Using Spin-Coating Technique
摘要： Ba1-xGdxTiO3+δ, at x = 0, 0.05, 0.1, 0.15, 0.2, (BGT) thin films have been fabricated on SiO2/Si substrate using sol-gel method. The microstructure and surface morphology of the fabricated films have been investigated using X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD results show that the fabricated films are crystalline with perovskite structure. There is a shifting of the preferred peak at 31.5° to a higher angle as the doping ratio increases suggesting a distortion lattice exists in the films, which could be due to the substitution of Gd3+ ions into Ba-site. The decreasing of lattice constants confirms the substitution of Gd3+ in BaTiO3 lattice structure. The microstrain and dislocation density are found to be increased with the increase of Gd3+ doping, which attributed to the reduction of lattice volume that due to the ionic size mismatch effect. The AFM results show decreasing trend in both average grain size and roughness parameters. Therefore, the microstructure and surface morphology of BGT samples is strongly dependent on the Gd3+ doping concentration that mainly due to the difference ionic radius substitution.
关键词： microstructure,thin film,barium titanate,sol-gel,gadolinium doping
更新于2025-09-19 17:15:36
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Controlled hydrothermal synthesis of different sizes of BaTiO<sub>3</sub> nano-particles for microwave absorption
摘要： Different sizes of barium titanate (BaTiO3) nano-particles were synthesized from precursor H2Ti3O7 nanotubes through facile hydrothermal synthesis by using EtOH/H2O as mixing solvent. Field-emission scanning electron microscopy (FESEM) was mainly used to investigate the effects of solution alkalinity, polarity, and hydrothermal temperature on the size and morphology evolution of BaTiO3 nanoparticles. The results indicate that the presence of strong alkalinity improved the size evenness of BaTiO3 nanoparticles possibly because of the re-dissolution and re-precipitation of TiO3 2- ions. As for the reason, the addition of EtOH could lower the polarity of hydrothermal medium and make the medium reach the supersaturation more easily, thus limiting the size growth of BaTiO3 particles. In addition, the presence of EtOH led to easier formation of BaTiO3 nanoparticles even at mild hydrothermal temperature, but the particle size was limited even though the temperature was much increased. This is possibly due to lowered interfacial activity in the presence of EtOH. By adjusting solution alkalinity, EtOH/H2O volume ratios, and hydrothermal temperature, BaTiO3 nanoparticles with the average sizes of approximately 21, 53, 104, 284, and 512 nm, were obtained, and more different and controlled nano-sizes can be expected by further hydrothermal adjustment. In the end, microwave absorption evaluation indicated that the decreased size of the BaTiO3 particles enhanced the reflection loss. One possible reason is that the decreased nano-size led to the increased specific surface area of the BaTiO3 nanoparticles.
关键词： Hydrothermal synthesis,Barium titanate,Polarity,Temperature,Microwave absorption,Adjustable nano-size
更新于2025-09-16 10:30:52
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Ultra-Low Power Tuning in Hybrid Barium Titanate-Silicon Nitride Electro-Optic Devices on Silicon
摘要： As the optical analogue to integrated electronics, integrated photonics has already found widespread use in data centers in the form of optical interconnects. As global network traffic continues its rapid expansion, the power consumption of such circuits becomes a critical consideration. Electrically-tunable devices in photonic integrated circuits contribute significantly to the total power budget as they traditionally rely on inherently power-consuming phenomena such as the plasma dispersion effect or the thermo-optic effect for operation. Here, we demonstrate ultra-low power refractive index tuning in a hybrid barium titanate (BTO)-silicon nitride (SiN) platform integrated on silicon. We achieve tuning by exploiting the large electric field-driven Pockels effect in ferroelectric BTO thin films of sub 100 nm thickness. The extrapolated power consumption for tuning a free spectral range (FSR) in racetrack resonator devices is only 106 nW/FSR, several orders of magnitude less than many previous reports. We demonstrate the technological potential of our hybrid BTO-SiN technology by compensating thermally-induced refractive index variations over a temperature range of 20 °C and by using our platform to fabricate tunable multi-resonator optical filters. Our hybrid BTO-SiN technology significantly advances the field of ultra-low power integrated photonic devices and allows for the realization of next-generation efficient photonic circuits for use in a variety of fields, including communications, sensing, and computing.
关键词： ferroelectric,Pockels effect,silicon nitride,electro-optic,barium titanate,integrated photonics,optical tuning
更新于2025-09-16 10:30:52
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Dielectric and thermal behavior of 0.75BiFeO3-0.25BaTiO3 filled ethylene vinyl acetate Composites
摘要： Bismuth ferrite-Barium Titanate (BFO-BT) filled ethylene-vinyl acetate copolymer (EVA) composites have been processed by solution casting technique followed by compression molding. The effects of BFO-BT on structural, thermal and dielectric behaviour of the composites have been investigated using X-ray diffraction, field emission scanning electron microscopy, thermal analysis (DSC, TGA) and impedance analyser. As analysed by XRD and DSC analyses, with increase in BFO-BT content the crystallinity of EVA matrix decreases. BFO-BT has great effect on higher thermal stability of the composites. EVA/ BFO-BT composites exhibit significantly enhanced relative dielectric permittivity (εr =182) near the percolation limit of about 30 phr BFO-BT loading at 25° C and 1kHz frequency. With 30 phr BFO-BT loading, the dielectric loss of the composite shows only an approximately 2-fold increase i.e., from 0.04 to 0.091. The capacitance and resistance of grains is found from the exploratory Nyquist plots with the assistance of an electrical circuit. A cautious examination of the experimental complex impedance plots and model fitted plots is contemplated which fulfilled the precision of the information tentatively. With enhanced dielectric properties and thermal stability, the BFO-BT filled EVA composite system can be used for solar cells and energy saving devices.
关键词： Composites,Nyquist plots,Dielectric,Conductivity,Ethylene Vinyl Acetate,Bismuth Ferrite-Barium Titanate
更新于2025-09-12 10:27:22
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A study on electro-optical properties of polymer dispersed liquid crystal films doped with barium titanate nanoparticles prepared by nucleophile-initiated thiol-ene click reaction
摘要： Polymer-dispersed liquid crystal (PDLC) films doped with barium titanate (BTO) nanoparticles were prepared by nucleophile-initiated thiol-ene click reaction. The effects of BTO content and reaction temperature on the electro-optical properties of PDLC were explored. It is found that the size of liquid crystal droplets is bigger when the amount of BTO increases. As the BTO content increases, the transmittance first rises and then falls, while the voltage that drives the liquid crystal orientation first drops and then rises. The electro-optical properties of PDLC doped with BTO show a similar changing trend with the change of reaction temperature. However, when the reaction temperature becomes higher, the influence of BTO on the electro-optical properties of PDLC becomes greater. Doping BTO helps to obtain PDLC films with good electro-optical properties.
关键词： reaction temperature,PDLC,barium titanate nanoparticles,electro-optical properties
更新于2025-09-12 10:27:22
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Ferroelectric barium titanate derivatives containing Mo and Mg for transparent photovoltaic applications
摘要： Using first-principles methods, we investigate the electronic properties of the [Ba(Mo1/2,Mg1/2)O3]x-[BaTiO3]1?x solid solution derived from barium titanate as a potential candidate to be used in photovoltaic devices. Focusing on the bandgap and its origin, we study the effect of different possible Mo and Mg contents, arrangements, and phases of [Ba(Mo1/2,Mg1/2)O3]x-[BaTiO3]1?x. We find that [Ba(Mo1/2,Mg1/2)O3]0.25-[BaTiO3]0.75 is a viable candidate for use in transparent photovoltaics due to its energy bandgap of 2.6 eV in the rhombohedral phase. In all cases, [Ba(Mo1/2,Mg1/2)O3]x-[BaTiO3]1?x materials exhibit spontaneous polarization that allows the exploitation of the bulk photovoltaic effect and in principle may allow high power conversion efficiency exceeding the Shockley-Queisser limit for these materials.
关键词： ferroelectric,photovoltaic,transparent,bandgap,barium titanate
更新于2025-09-11 14:15:04
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Island growth mode in pulsed laser deposited ferroelectric BaTiO <sub/>3</sub> thin films: The role of oxygen pressure during deposition
摘要： Pulsed laser deposition is widely used to grow BaTiO3 thin films. We investigated the influence of oxygen pressure during growth on the topography, microstructure, and roughness of ferroelectric epitaxial BaTiO3 thin films. It also presented an analysis of the epitaxial growth mode and defects throughout the film thickness using aberration-corrected transmission electron microscopy. Although ferroelastic (twin boundary) domain walls are absent, several misfit dislocations were observed and might be the primary cause of the observed island growth mode.
关键词： barium titanate,Ferroelectric thin film,epitaxial thin film,misfit strain,crystalline defects
更新于2025-09-11 14:15:04
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First-principle study of the polarization, atomic displacements and electronic structure of angular-deformed barium titanate
摘要： The in?uence of β and γ angular deformation on polarization, TieO(3) bond distances, atomic displacements, number of states, valence charge distributions and valance charge asymmetry of barium titanate (BaTiO3) has been investigated using local density approximation. The results show that for all angles of 89.5°≤ β&γ ≤ 90.5°, there is a clear correlation between polarization, TieO(3) bond distances, atomic displacements and number of 2 orbital. For the case of γ-deformation the values of polarization and the other parameters are approximately constant in the range of 89.8°≤γ ≤ 90.2° and an abnormal behavior is observed at γ = 89.6°. In this case valence charge asymmetry of Ti 3d orbital has a direct relation with the polarization and atomic displacements of Ti atoms for the whole region of γ, especially at γ = 89.6°. In the case of β-deformation, an approximately symmetrical behavior versus β variations is observed for all above-mentioned parameters. In this case, a direct relation between valence charge asymmetry of Ti 3d orbital, polarization and atomic displacements is remarkable only for β > 89.8° and the region of β < 89.8° does not reveal such a direct relation.
关键词： Electronic investigation,Angular deformation,DFT,Atomic displacements,Barium titanate
更新于2025-09-11 14:15:04
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Recent Advances in Porous Ceramics || Physical Properties of Porous Pure and Zr/Sn-Doped Nanocrystalline BaTiO3 Ceramics
摘要： Polycrystalline BaTiO3 and Ba(Ti0.96SnxZr0.04-x)O3 ceramics (x=0.02-0.04) were prepared by a combination of solid-state and mechanochemical process and characterized at room temperature by X-ray diffraction for phase composition. Their crystal structures were found to be of the cubic and tetragonal symmetries, respectively. The grain size and porosity which were determined using Field Emission Scanning Electron Microscope (FESEM) and densitometer, respectively showed decrease and increase of relative density respectively, with increase in doping concentration. The variations of dielectric constant and loss with frequency and temperature show a maximum dielectric constant of 1660 at room temperature for Ba(Ti0.96Sn0.03Zr0.01)O3. The remnant polarization (Pr) and coercive field (Ec) of BT were found to be 581.73 V/cm and 0.27 μC/cm2. Increase in Sn content led to an increase in Pr of 0.58, 3.07, 3.73 C/cm2, and Ec of 1766.8, 2855.7, 2661.1 V/cm, respectively and are expected to lead to a significant reduction in the thickness of the multilayer ceramic capacitors. Impedance spectroscopy of polycrystalline Ba(Ti0.96Sn0.02Zr0.02)O3 in a wide frequency and temperature range showed Nyquist plots with presence of grain and grain boundary at 400°C and a negative temperature coefficient of resistance (NTCR) for Ba(Ti0.96Sn0.02Zr0.02)O3. The dielectric relaxation showed a non-Debye character.
关键词： porous ceramics,barium titanate,doping,MLCC,ferroelectrics
更新于2025-09-10 09:29:36
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Effects of grain size and temperature on the energy storage and dielectric tunability of non-reducible BaTiO3-based ceramics
摘要： BaTiO3-based ceramics with various grain sizes (136-529 nm) are prepared through a chemical coating method followed by sintering in a reducing atmosphere. Effects of grain size and temperature on electric properties, energy-storage properties, and dielectric tunability are studied via Current-Field (J-E) curves, ferroelectric hysteresis loops, Capacitance-Voltage (C-V) curves and Thermally stimulated depolarization currents (TSDC). At all temperatures, fine-grain ceramics yield a lower energy density but a higher energy efficiency under the same electric field, owing to a lower ferroelectric contribution. Meanwhile, fine-grain ceramics exhibit a higher maximum energy density due to their higher breakdown strength. Fine-grain ceramics with the grain size of 136 nm have the maximum energy density of 0.41 J/cm3 under the breakdown strength of 75 kV/cm, the corresponding efficiency is 81%. C-V curves show that fine-grain ceramics have better bias-field stability. According to TSDC results, fine-grain ceramics exhibit fewer oxygen vacancies and a higher relaxation activation energy.
关键词： non-reducible,grain size,dielectric tunability,energy storage,Barium titanate
更新于2025-09-10 09:29:36