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Non‐Stoichiometry Induced Switching Behavior of Ferroelectric Photovoltaic Effect in BaTiO <sub/>3</sub> Ceramics
摘要： Ferroelectric photovoltaic (FPV) effect has been studied among a series of non-stoichiometric BaTiO3 (Ba/Ti ? 0.92–1.05) ceramic chips prepared by tape casting method. The FPV performance increases abruptly when the Ba/Ti molar ratio deviates from the stoichiometry within 1%. Meanwhile, a photocurrent direction switching behavior is observed between Ti-excess and Ba-excess samples. The TEM analysis shows their significant difference in grain-boundary (GB), where abnormal GB with a width of 10–15 nm is observed in Ba-excess sample. The photocurrent switching phenomenon is described to the competition between the asymmetrical Schottky barriers induced PV effect and intrinsic FPV effect. Widen GB in Ba-excess BaTiO3 ceramics restrains the intrinsic FPV effect and results in the switching behavior. This study offers direct evidence of the vital role of GB in FPV effect and may promote the development of photovoltaic devices.
关键词： ferroelectric photovoltaic,barium titanate,non-stoichiometry,switching behavior
更新于2025-11-21 11:03:13
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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
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Conventionally Sintered Hydroxyapatite–Barium Titanate Piezo-Biocomposites
摘要： The central goal of this initial effort is to develop and characterize distinctive piezo-biocomposites as load-bearing orthopedic implants. The motivation is derived from the fact that mammalian bone is a piezoelectric material and this property is helpful in the natural healing of fractured bone. We have employed a cost-effective and industrially viable technique—conventional sintering to consolidate specific compositions of hydroxyapatite (HA) and barium titanate (BT). HA is the primary mineral constituent of mammalian bone but is not piezoelectric. On the contrary, BT is well known for its piezoelectric properties. Their combination creates piezo-biocomposites. The sintering is reactive in nature as BT decomposes into several compounds. Average grain sizes of piezo-biocomposites lie in the range of 1.75–1.9 μm. Interestingly, 15% compressive strength enhancement is noted in the case of HA-40 wt% BT as compared to HA. In vitro examinations reveal favorable bioactivity and biocompatible nature of the composites. These results show that conventionally sintered HA-BT piezo-biocomposites can qualify as candidate materials for load-bearing implants at affordable prices.
关键词： Orthopedic implants,Conventional sintering,Hydroxyapatite,Barium titanate
更新于2025-09-23 15:22:29
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Sensitivity enhancement of surface plasmon resonance biosensor based on graphene and barium titanate layers
摘要： A surface plasmon resonance-based biosensor, consisting prism, silver, barium titanate (BaTiO3) and graphene layers, is presented by using angular interrogation. The structure is specially designed to further enhance the sensitivity and to decrease the full width at half maximum (FWHM) thereby improving the sensor performance. Theoretical analysis shows that the highest sensitivity can reach at 257°/RIU where the thickness of Ag layer is 45 nm with 10 nm BaTiO3 and one graphene layer. Compared with existing biosensors, the proposed biosensor exhibits higher sensitivity, lower FWHM and two times better preformation in the quality factor of the sensor, which would make our design have more applications in the field of biosensors.
关键词： Biosensor,Barium titanate,Graphene,Sensitivity,Surface plasmon resonance
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Cancun (2018.8.29-2018.8.31)] 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Electric Field Tuning of BaTiO<inf>3</inf>-on-Silicon Multi-Ring Resonators via the Pockels Effect
摘要： We demonstrate optical tuning in hybrid barium titanate-silicon photonic structures. Individual resonances of a multi-ring resonator are coalesced into a single resonance. Critically, device operation is stable in time. Our devices enable adjustable wavelength filters and offer a low power solution to compensate fabrication imperfections.
关键词： Ring resonator,Barium titanate,Silicon photonics,Pockels
更新于2025-09-23 15:22:29
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Study on properties of barium titanate/polyethersulfone dielectric composites prepared by physical dispersion method
摘要： Composite materials applied to capacitors with high dielectric constant, low dielectric loss and outstanding thermal stability are concerned widely in the field of dielectrics. So committed to the development of dielectric materials with excellent performance is the key factor. In this work, the barium titanate/polyether sulfone (BaTiO3/PES) composite films were prepared by a physical dispersion technology, which utilized a ball milling machine by high-speed circulation, scattered the PES solution contained BaTiO3 in deionized water with the aid of a surfactant. Then, the BaTiO3/PES composite films were obtained through a series of operations, containing reclaimed organic solvent, washed with deionized water, filtered, dried and hot pressed. The morphology of the BaTiO3/PES emulsion was investigated by TEM and SEM. The results showed that the BaTiO3 particles were covered in the PES resin matrix homogeneously. For 50?wt% BaTiO3 reinforced PES composite film. The dielectric constant increased by ~ 227% compared with pure PES resin (4.1 at 1?kHz) and the dielectric loss maintained around 10?2 magnitude, which performed better dielectric properties. The tensile strength of 10?wt% BaTiO3/PES composite films (72?MPa) reached the highest value in comparison with those of pure PES (58?MPa) due to the strengthened interaction between particles and matrix. Further increase of BaTiO3 content, the tensile strength and elongation at break decreased slightly but remained an excellent flexibility from the PES matrix. The temperature at weight loss 5% (T5%) of composite film with 40?wt% of BaTiO3 content reached up to 503?°C in N2 atmosphere. All the BaTiO3/PES composite films performed the concentrated glass transition temperature (Tg) around 229?°C. In sum, excellent thermal stability and dielectric properties would make the BaTiO3/PES composite films become the fine potential candidates for dielectric composites in the capacitors.
关键词： barium titanate,dielectric composites,polyethersulfone,physical dispersion method
更新于2025-09-23 15:21:21
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Investigation on the structural, multiferroic and magnetoelectric properties of BaTi1-xNixO3 ceramics
摘要： In this paper, we report the influence of Ni doping on the structural, electrical, magnetic and magnetoelectric properties of BaTiO3 (BTO) ceramics. X-ray diffraction (XRD) analysis indicates a phase transition from tetragonal to hexagonal at x = 2.5 mol%. Further, XRD data has been refined using Rietveld method to extract the phase formation, lattice parameters, and the phase fraction of BaTi1-xNixO3 (BTNO)(0 ≤ (cid:129) ≤ 10 mol%) ceramics. The ferroelectric polarization decreases with Ni doping concentration. The relative permittivity of BTNO compositions decreases while the corresponding dielectric loss increases with Ni doping concentration. Room temperature magnetic hysteresis (M-H) loop of all BTNO samples exhibit ferromagnetic nature with a saturated loop except for x = 2.5 mol% Ni doping concentration. At x = 2.5 mol% Ni doping concentration, a small amount of diamagnetism is observed at higher fields along with ferromagnetism. The origin of ferromagnetism is due to the F- center exchange interaction via oxygen vacancies. The highest remnant magnetization (Mr) is 11.76 memu/g for x = 10 mol%. The Magnetodielectric coefficient (MD) and magnetoelectric coefficient (ME) gradually increases with increasing Ni doping concentration, and are 1.72 % and 4.51 mVcm !Oe ! respectively for x = 10 mol%.
关键词： ferroelectric,magnetoelectric,Barium titanate,magnetic,multiferroic,Perovskite
更新于2025-09-23 15:21:01
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Synthesis and Characterization ofBaTiO3/Polypyrrole Composites with Exceptional Dielectric Behaviour
摘要： Higher concentrations of ceramic fillers induce brittleness in the ceramic/polymer hybrids which restrict their applications to limited fields especially when such hybrids are prepared for their use as dielectrics. We have synthesized and characterized different BaTiO3-polypyrrole (PPy) composites by changing the concentration of BaTiO3 from 1% by weight of PPy taken to 5 wt % to explore its effect on the dielectric parameters of the final product and found that the BaTiO3-polypyrrole composite with weight ratio of 0.05:1 exhibited highest dielectric constant, lowest dielectric loss and thermally most stable. All the composites were prepared using in-situ polymerization of pyrrole in an aqueous dispersion of low content of BaTiO3 in the presence of small amount of Hydrochloric acid. These composites were characterized for their microstructure and crystallinity by X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) while thermal stability by thermo gravimetric (TGA) analysis. An impedance analyser (LCR meter) was utilized to investigate the dielectric parameters. FT-IR data confirmed the presence of the two phases and their interaction, inferred from the shifting of normal PPy peaks. The data obtained from XRD confirmed the presence of crystallites of 2.8 to 5 nm with dominant crystallinity of the filler, TGA analysis (25 to 600 ?C) confirmed the higher thermal stability induced on successive addition of the filler into the prepared composites as compared to that of pure PPy in a wide temperature range which is unusual for such a low % age addition of the filler. The SEM analysis together with XRD results reveal that the successive introduction of BaTiO3 particles produced crystallites of 2 to 5 nm size which bonded together and changed the hemispherical shaped larger grains of the matrix to regular shaped smaller grains. The dielectric constant of the composites was enhanced with filler contents from 178 to 522 at 1 MHz for 1 wt % and 5 wt % BaTiO3 respectively. It was concluded that the introduction of BaTiO3 into the polymer matrix with this new procedure has greatly affected the polymerization process, thermal stability, morphology and dielectric properties of the host matrix and has resulted in a novel series of the composites which may have broad applications.
关键词： barium titanate,polymerization,dielectric behaviour,polypyrrole
更新于2025-09-23 15:21:01
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Successive redox-mediated visible-light ferrophotovoltaics
摘要： Titanium oxide materials have multiple functions such as photocatalytic and photovoltaic effects. Ferroelectrics provide access to light energy conversion that delivers above-bandgap voltages arising from spatial inversion symmetry breaking, whereas their wide bandgap leads to poor absorption of visible light. Bandgap narrowing offers a potential solution, but this material modification suppresses spontaneous polarization and, hence, sacrifices photo-voltages. Here, we report successive-redox mediated ferrophotovoltaics that exhibit a robust visible-light response. Our single-crystal experiments and ab initio calculations, along with photo-luminescence analysis, demonstrate that divalent Fe2+ and trivalent Fe3+ coexisted in a prototypical ferroelectric barium titanate BaTiO3 introduce donor and acceptor levels, respectively, and that two sequential Fe3+/Fe2+ redox reactions enhance the photogenerated power not only under visible light but also at photon energies greater than the bandgap. Our approach opens a promising route to the visible-light activation of photovoltaics and, potentially, of photocatalysts.
关键词： ferrophotovoltaics,redox reactions,barium titanate,photovoltaic effect,visible-light response
更新于2025-09-23 15:19:57
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Space charge limited conduction in pulsed laser deposited BaTiO3/LaNiO3 hetero-junctions
摘要： We report the charge transport mechanism in BaTiO3 (BTO) thin film deposited on LaNiO3 (LNO) buffer layer using pulsed laser deposition technique thus, forming the metal – insulator – metal junction (Au/BTO/LNO). The temperature dependent Current density- Voltage (J-V) characteristics were measured, analyzed and compared with the La0.67Ca0.33MnO3 (LCMO) buffered BTO film (Au/BTO/LCMO). Although the mechanism was found to be space charge limited conduction (SCLC) as in case of BTO/LCMO but the absence of Ohmic region in Log J-Log V plot indicates higher injection rate. Various parameters such as trap density, activation energy, and ratio of free to trapped carriers (h) were extracted out from the fitted J-V plot and subsequently their temperature dependence was studied and compared with BTO/LCMO. Higher current density, lower activation energy, lower trap density and higher ratio of free to trapped carriers (h) were observed in BTO/LNO in contrast to BTO/LCMO. Furthermore, the lower activation energy indicates the presence of shallow trap level.
关键词： Non-volatile memories,Barium titanate,Metal-Insulator-Metal junction,Space charge limited conduction,Pulsed laser deposition
更新于2025-09-23 15:19:57