- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Dielectric tunable properties of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics prepared by spark plasma sintering
摘要： Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics were prepared by spark plasma sintering (SPS) technique and their phase composition, microstructures and dielectric tunable properties were studied. With increasing Mg2TiO4?MgO content, the dielectric peaks of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics were broadened and suppressed. The tunability of Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics first increased and then decreased with the increase of Mg2TiO4?MgO content. For Mg2TiO4?MgO content ≤ 50 wt%, Ba0.5Sr0.5TiO3?Mg2TiO4?MgO composite ceramics showed higher tunability and lower permittivity than pure Ba0.5Sr0.5TiO3, which can be attributed to the suppression of the doping effect by SPS. The contradiction between reduced permittivity and enhanced tunability in ferroelectric-dielectric composites was resolved.
关键词： Dielectrics,Ferroelectric ceramics,Spark plasma sintering,Composites
更新于2025-11-14 17:28:48
-
Engineered thiol anchored Au-BaTiO3/PVDF polymer nanocomposite as efficient dielectric for electronic applications
摘要： In modern electronic and electric appliances industries, polymer nanocomposites-based capacitors comprising of high dielectric constant ceramics (eg. BaTiO3 (BT), SrTiO3, CaCu3Ti4O12, etc.) and polymers (eg. polyvinyledene fluoride (PVDF), polyethylene terephthalate (PET), polycarbonate (PC), etc.) are becoming attractive for electrical energy storage applications. High dielectric constant fillers improve the energy density of the capacitors but at the cost of decreased efficiency, large dielectric loss as well as electrical conduction at high fields. In this paper, we present novel dielectric core-satellite BT-Au NPs for high energy density capacitor application. Hydroxylated barium titanate nanoparticles (BTO NPs) were immobilized with gold (Au) nanoparticles of size ~4 nm and were used as fillers into PVDF polymer matrix. The results show that the incorporation of Au on BaTiO3 nanoparticles improved the dielectric constant, energy density as well as efficiency, while reduction in the dielectric loss. To further improve the dielectric properties, Au-BTO NPs were coated with 2,3,4,5,6-Pentafluorothiophenol (PFTP) layer. The dielectric properties were further tuned with different PFTP concentrations. The PFTP serves as the bridge between nanoparticle and PVDF polymer by forming hydrogen bonding. The dielectric properties were measured at two different PFTP concentrations (PFTP1 and PFTP1.5, where 1 and 1.5 refers to the molar ratio of PFTP and Au decorated BaTiO3). The lower PFTP concentration results in improved dielectric properties, while increasing the concentration decreases the overall performance of the capacitors. The energy density of PFTP1@Au@BTO/PVDF was 2.04 J cm-3 at ~2100 kV cm-1 which was ~21% higher than that of PVDF and 70% higher than biaxially oriented polypropylene (BOPP), a present state-of-the art dielectric polymer. Thus, the combination of both, Au decoration on BT NPs and hydrogen bonding of PFTP with PVDF chains are responsible for improved dielectric properties and make these nanocomposites a promising candidate for energy storage applications.
关键词： Dielectrics,BaTiO3 nanoparticles,Polymer composites,Capacitors
更新于2025-11-14 17:28:48
-
Significantly Enhanced Energy Density by Tailoring the Interface in a Hierarchical-Structured TiO2-BaTiO3-TiO2 Nanofillers in PVDF Based Thin Film Polymer Nanocomposite
摘要： Dielectric polymer nanocomposites with high breakdown field and high dielectric constant have drawn significant attention in modern electrical and electronic industries due to their potential applications in dielectric and energy storage systems. The interfaces of the nanomaterials play a significant role in improving the dielectric performance of polymer nanocomposites. In this work, polydopamine (dopa) functionalized TiO2-BaTiO3-TiO2 (TiO2-BT-TiO2@dopa) core@double-shell nanoparticles have been developed as novel nanofillers for high energy density capacitor application. The hierarchically designed nanofillers help in tailoring the interfaces surrounding the polymer matrix as well as act as individual capacitors in which core and outer TiO2 shell functions as capacitor plate because of their high electrical conductivity while the middle BT layer functions as a dielectric medium due to high dielectric constant. Detailed electrical characterizations have revealed that TiO2-BT-TiO2@dopa/PVDF possess maximum relative dielectric permittivity (εr), breakdown strength (Eb), as well as energy densities in comparison to PVDF, TiO2/PVDF, TiO2@dopa/PVDF, TiO2-BT@dopa/PVDF polymer nanocomposites. The εr and energy density of TiO2-BT-TiO2@dopa/PVDF was 12.6 at 1 kHz and 4.4 J cm-3 at 3128 kV cm-1, respectively, which was comparatively much higher than commercially available biaxially oriented polypropylene (BOPP) having εr of 2.2 and the energy density of 1.2 J cm-3 at much higher electric field of 6400 kV cm-1. It is expected that these results will further open new avenues for the design of novel architecture for high-performance polymer nanocomposites-based capacitors having core@multishell nanofillers with tailored interfaces.
关键词： capacitors,polymer nanocomposites,core-shell nanomaterials,dielectrics,BaTiO3 nanoparticles
更新于2025-11-14 15:19:41
-
Studies on optical, electrical, mechanical and theoretical investigation of 4-nitro-benzoic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide: A novel Schiff base organic NLO material
摘要： New organic non-centrosymmetric Schiff base material 4-Nitro-benzoic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide was synthesized and grown as single crystal by slow evaporation solution growth technique. Single crystal X-ray diffraction reveals the noncentrosymmetric nature of the grown crystal with space group Pna21. The nonlinear efficiency of the grown material was studied by Kurtz-Perry powder technique and found to be 0.7 times that of KDP. The photoluminescence emission of the grown crystal shows emission at 360 nm. The mechanical stability of the crystal was examined by Vicker’s microhardness study and the yield strength of the material was calculated. Low dielectric constant at higher frequencies was observed from dielectric measurements. Reduction in charge carriers when the sample was illuminated by halogen lamp proves the negative photoconductivity of the sample. In addition, quantum chemical calculations were carried out using density functional theory for the NEH molecule optimized at B3LYP/6-31+G (d, p) basis set to calculate its frontier molecular orbital, Electrostatic potential and Mulliken charge analysis.
关键词： DFT,Dielectrics,Schiff base,non-centrosymmetric,Crystal growth
更新于2025-09-23 15:23:52
-
Influence of porosity and pore size on sputtering of nanoporous structures by low-energy Ar ions: Molecular dynamics study
摘要： In this paper we have carried out molecular dynamics simulation of the low-energy Ar ion irradiation of nanoporous homogeneous material with different porosity and pore sizes. Our results demonstrate that in a model with small pores (Rpore = 0.8 nm) and relatively low (22%) porosity, the pores at near-surface layers collapsed due to the ion bombardment, whereas in a model with larger pores (Rpore = 2.8 nm) and higher (44%) porosity no significant structural changes occurred under the same irradiation conditions. To study thermal stability of porous structures and to reveal the effects of both the pore radius and the porosity on pore collapsing, our nanoporous structures were subjected to gradual heating. The simulation results demonstrate distinct mechanisms of structural changes in the nanoporous materials depending on the value of the excess surface energy per unit volume.
关键词： low-k dielectrics,plasma treatment,nanoporous material,pore collapse,sputtering
更新于2025-09-23 15:23:52
-
Reshaping the Second-Order Polar Response of Hybrid Metal–Dielectric Nanodimers
摘要： We combine the field confinement of plasmonics with the flexibility of multiple Mie resonances by bottom-up assembly of hybrid metal-dielectric nanodimers. We investigate the electromagnetic coupling between nanoparticles in heterodimers consisting of gold and barium titanate (BaTiO3 or BTO) nanoparticles through nonlinear second-harmonic spectroscopy and polarimetry. The overlap of the localized surface plasmon resonant dipole mode of the gold nanoparticle with the dipole and higher-order Mie resonant modes in the BTO nanoparticle lead to the formation of hybridized modes in the visible spectral range. We employ the pick-and-place technique to construct the hybrid nanodimers with controlled diameters by positioning the nanoparticles of different types next to each other under a scanning electron microscope. Through linear scattering spectroscopy, we observe the formation of hybrid modes in the nanodimers. We show that the modes can be directly accessed by measuring the dependence of the second-harmonic generation (SHG) signal on polarization and wavelength of the pump. We reveal both experimentally and theoretically that the hybridization of plasmonic and Mie-resonant modes leads to a strong reshaping of the SHG polarization dependence in the nanodimers, which depend on the pump wavelength. We compare the SHG signal of each hybrid nanodimer with the SHG signal of single BTO nanoparticles to estimate the enhancement factor due to the resonant mode coupling within the nanodimers. We report up to two orders of magnitude for the SHG signal enhancement compared to isolated BTO nanoparticles.
关键词： Dielectrics,Second-harmonic generation,Barium Titanate,Polar-dependence,Hybrid nanoantennas,Plasmonics
更新于2025-09-23 15:23:52
-
Electrowetting on 2D dielectrics: a quantum molecular dynamics investigation
摘要： Electrowetting on dielectrics (EWOD) is widely used to manipulate the spreading of a conductive liquid on a dielectric surface by applying an electric field. 2D hydrophobic dielectrics are promising candidates for EWOD applications. In this study, extensive quantum molecular dynamics (MD) simulations are performed to investigate the electrowetting behavior of salty water on hexagonal boron nitride (h-BN) monolayer. The proximal adsorption of salt ions and the associated realignment of the dipole moments of interfacial water with the applied electric field are found to be the physical origin of the electrowetting behavior. At low salt concentration and low electric fields, the proximal adsorption and the realignment follow the applied electric field, and the cosine of the water contact angle (WCA) follows a quadratic dependence on the applied electric field. At high salt concentration and high electric fields, the proximal adsorption saturates, which restricts further realignment and causes a saturation of the WCA. This case study provides physical insights into the much debated mechanism that underlies the contact angle saturation (CAS) found in macroscopic electrowetting phenomena and also provides an avenue for further studies of electrowetting at the atomic scale.
关键词： hexagonal boron nitride monolayer,contact angle saturation,electrowetting on dielectrics,first-principles
更新于2025-09-23 15:23:52
-
Electrowetting (Fundamental Principles and Practical Applications) || Electrostatics
摘要： Electrowetting (EW) is driven by electrostatic forces. While various basic aspects of electrostatics are taught in high school, EW involves a number of subtleties and somewhat more advanced concepts, e.g. regarding the details of the electric field distribution and forces in complex geometries as well as the response of materials to electric fields. This chapter therefore starts by recapitulating basic principles of electrostatics, focusing on the specific needs of electrowetting. Next to the fundamental laws, boundary conditions, and materials response to electric fields (conductor, dielectrics, leaky dielectrics), we discuss in particular complementary manners of calculating the resulting electrostatic forces based on general principles of energy gradients, global momentum conservation arguments, and local force balance. We will also discuss the solutions of a few specific electrostatic problems of particular interest for EW.
关键词： conductors,Maxwell stress tensor,electrostatics,leaky dielectrics,electric fields,electrowetting,capacitance,dielectrics
更新于2025-09-23 15:22:29
-
Electrical properties of 4H-SiC MIS capacitors with AlN gate dielectric grown by MOCVD
摘要： We report on the electrical properties of the AlN/4H-SiC interface using capacitance- and conductance-voltage (CV and GV) analysis of AlN/SiC MIS capacitors. The crystalline AlN layers are made by hot wall MOCVD. CV analysis at room temperature reveals an order of magnitude lower density of interface traps at the AlN/SiC interface than at nitrided SiO2/SiC interfaces. Electron trapping in bulk traps within the AlN is significant when the MIS capacitors are biased into accumulation resulting in a large flatband voltage shift towards higher gate voltage. This process is reversible and the electrons are fully released from the AlN layer if depletion bias is applied at elevated temperatures. Current-voltage (IV) analysis reveals that the breakdown electric field intensity across the AlN dielectric is 3–4 MV/cm and is limited by trap assisted leakage. By depositing an additional SiO2 layer on top of the AlN layer, it is possible to increase the breakdown voltage of the MIS capacitors significantly without having much impact on the quality of the AlN/SiC interface.
关键词： AlN/4H-SiC interface,MIS capacitors,Gate dielectrics
更新于2025-09-23 15:22:29
-
Charge Transfer Tuned by the Surrounding Dielectrics in TiO2-Ag Composite Arrays
摘要： TiO2/Ag bilayer ?lms sputtered onto a 2D polystyrene (PS) bead array in a magnetron sputtering system were found to form a nanocap-shaped nanostructure composed of a TiO2-Ag composite on each PS bead, in which the Ag nanoparticles were trapped partially or fully in the TiO2 matrix, depending on the TiO2 thickness. X-ray Photoelectron Spectroscopy (XPS) results showed the opposite shifts of binding energy for Ti 2p and Ag 3d, indicating the transfer of electrons from metallic Ag to TiO2 owing to the Ag-O-TiO2 composite formation. UV-Vis absorption spectra showed the blue shifts of the surface plasma resonance peaks, and the maximum absorption peak intensity was obtained for TiO2 at 30 nm. The surface-enhanced Raman scattering (SERS) peak intensity ?rst increased and then decreased when the TiO2 thickness changed. The observations of SERS, XPS, and UV-Vis absorption spectra were explained by the dependency of the charge-transfer process on TiO2 thickness, which was ascribed to the changing dielectric properties in the metal/semiconductor system.
关键词： electronic transfer,TiO2-Ag composites,surrounding dielectrics
更新于2025-09-23 15:22:29