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Flexible and Ultrasensitive Piezoelectric Composites Based on Highly (00l)‐Assembled BaTiO <sub/>3</sub> Microplatelets for Wearable Electronics Application
摘要： Piezoelectric wearable electronics with flexibility and high sensitivity have received increasing attention in the fields of health monitoring, flexible robots, and artificial intelligence. Here, a flexible organic–inorganic hybrid composite for wearable electronics application based on (00l)-aligned BaTiO3 (BT) single-crystal microplatelets is prepared by layer-by-layer self-assembly technology. For the polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE))/BT single-crystal microplatelets composite film, the sensitivity is nearly 20 times higher than that of its counterparts of P(VDF-TrFE)/BT microparticles composite film and pure P(VDF-TrFE) film. The orderly alignment of BT microplatelets also has been found advantageous to the strength of the composite film. The tensile strength is up to 204.3 MPa even at a high inorganic phase content of 53.8 wt% in P(VDF-TrFE)/BT single-crystal microplatelets composite film, which is four times that of pure P(VDF-TrFE) film. Moreover, the flexible piezoelectric wearable device based on P(VDF-TrFE)/BT single-crystal microplatelets film effectively provides detailed information for monitoring human activities such as pronunciation, frequency, and waveform of pulse beating, and motion states. This high sensitivity, high strength, and flexible piezoelectric composite provides much potential on the applications of wearable equipments and health monitoring devices.
关键词： organic–inorganic hybrids,wearable sensors,flexible piezoelectric composites,BaTiO3
更新于2025-11-21 11:01:37
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dz2 Orbitals Mediated Bound Magnetic Polarons in Ferromagnetic Ce Doped BaTiO3 Nanoparticles and its Enriched Two Photon Absorption Cross Section
摘要： Enriched ferromagnetism and two photon absorption (TPA) cross section of perovskite BaTiO3 nanoparticles are indispensible for magnetic and optical data storage applications. In this work, the hydrothermally synthesized Ce doped BaTiO3 nanoparticles exhibit the maximum room temperature ferromagnetism (4.26×10-3 emu/g) at 4 mol% due to the increase of oxygen vacancies as evidenced by X-ray photoelectron, electron spin resonance spectroscopies and density functional theory (DFT) calculations. Hence, the oxygen vacancy constituted bound magnetic polaron (BMP) model has been invoked to explain the enhancement of ferromagnetism. BMP theoretical model indicates the increase of BMP magnetization (M0, 3.0 to 4.8×10-3 emu/g) and true spontaneous moment per BMP (meff, 4 to 9.88×10-4 emu) on Ce doping. DFT calculations show that BMPs mediate via Ti d orbitals leading to the ferromagnetism. Besides, it is understood that the magnetic moment induced by Ce at Ba site is higher than Ce at Ti site in the presence of oxygen vacancies. Open aperture Z-scan technique displays the highest TPA coefficient β (7.08×10-10 m/W) and TPA cross section σTPA (455×104 GM) at 4 mol% of Ce as a result of robust TPA induced excited state absorption. A large σTPA is attributed to the longer excited state lifetime τ (7.63 ns) of charge carriers created by oxygen vacancies and Ce ions which encounter several electronic transitions in the excited sub-states.
关键词： Ce doping,oxygen vacancies,bound magnetic polarons,two photon absorption,DFT calculations,Z-scan technique,BaTiO3 nanoparticles,ferromagnetism
更新于2025-11-19 16:56:35
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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
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Improved densification behavior and energy harvesting properties of low-temperature sintered (Ba, Ca)(Zr, Ti)O3 piezoceramics with a CuO additive
摘要： Piezoelectric energy harvesting has recently attracted substantial interest because of its ability to provide sustainable power for devices that consume very small amounts of energy. In this work, we propose a CuO-doping strategy to develop environmentally friendly (Ba, Ca)(Zr, Ti)O3 (BCZT) piezoelectric energy harvesters with both low sintering temperatures and excellent power generation performance. The CuO dopant greatly promoted the densification behavior of BCZT ceramics, yielding a densified and fine-grained microstructure at a sintering temperature reduced by 125°C compared to that of undoped BCZT. Moreover, CuO addition substantially reduced the domain size compared to that of the undoped BCZT and thus facilitated domain switching in the ceramics. While maintaining the Curie temperature (Tc) at ~120oC, 0.50 mol% CuO-doped ceramics exhibited significantly enhanced electromechanical properties with a figure of merit d33×g33 of 6661×10-15 m2/N, high-field piezoelectric constant d33* of 873 pm/V, electromechanical coupling factor kp of 0.53 and energy conversion efficiency η of 97%. A high power density of 1.8 μW/mm3, which corresponds to a ~360% improvement relative to that of the undoped BCZT, was achieved from 0.50 mol% CuO-doped BCZT energy harvesters at 10 m/s2 acceleration. These findings suggest the tremendous potential of CuO-doped (Ba, Ca)(Zr, Ti)O3 piezoceramics in high-power-density energy harvesting applications.
关键词： A. Sintering,C. Electrical properties,D. BaTiO3,B. Microstructure
更新于2025-11-14 17:28:48
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Influence of aging on electrocaloric effect in Li+ doped BaTiO3 ceramics
摘要： Aging creates significant changes in the properties of the ferroelectric materials such as dielectric and piezoelectric properties. However, the influence of aging on the electrocaloric effect (ECE) has not yet been investigated. In this work, we investigate the effect of the aging on the ECE in acceptor (Li+) doped BaTiO3 ceramics. We observe that aging induced defect polarization (PD) reduces the saturation polarization of the doped samples until Tc=115 oC. Above that temperature PD loses its effectiveness and material behaves like a fresh sample. Suppression of polarization below TC due to aging effect results in a sharper slope change in the temperature dependence of electrical polarization in aged samples which causes an increase in the electrocaloric temperature change of Li+ doped BaTiO3 ceramics up to 23 % at TC. Above a critical Li doping amount, both negative and positive electrocaloric effect are observed in the same sample.
关键词： Aging,BaTiO3,Li-doping,Electrocaloric effect,Defect dipoles
更新于2025-11-14 17:28:48
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Temperature-dependent dielectric response of (1-x)PVDF/(x)BaTiO3 nanocomposite films
摘要： The PVDF/BaTiO3 nanocomposite films were prepared by solution casting method by using dimethylformamide as solvent. The dielectric constant and loss tangent of the PVDF and PVDF/BaTiO3 composites have been determined as functions of frequency (20 Hz to 2 MHz) and temperature (80 to 425 K). A significant enhancement in dielectric constant ε' is observed in composite samples. Tangent loss factor (tan δ) is maximum at lower frequencies due to interfacial polarization. In composite samples owing to the synthesis process, there is a phase transition in PVDF from α to β which results in the formation of dipolar relaxation. The dipolar nature of both the PVDF and PVDF/BaTiO3 nanocomposites is arrested below 200 K. The activation energy values (0.43- 0.69 eV) associated with tan δ peak in the region 200 – 270 K are in agreement with the activation energy associated with a dipolar relaxation process. The relaxation time (τ) decreases with increasing BaTiO3 filler content while the number density of dipoles increases from 4.06×1021 cm-3 for pristine PVDF to 6.62×1023 cm-3 for (0.5)PVDF/(0.5)BaTiO3 composite and confirms a significant amount of dipolar relaxation in PVDF/BaTiO3 composites.
关键词： dielectric relaxation,activation energy,dielectric constant,PVDF/BaTiO3 nanocomposites
更新于2025-11-14 17:28:48
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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
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Cellulose/BaTiO3 aerogel paper based flexible piezoelectric nanogenerators and the electric coupling with triboelectricity
摘要： Flexible piezoelectric nanogenerators (PENGs) with high output performance are highly desirable for energy harvesting. Coupling triboelectric nanogenerators (TENGs) with the PENGs is a feasible method to enhance the output performance, while the complicated structure and the requirement of skillful operation limited the development of hybridized nanogenerators. In this work, flexible high-performance PENGs are developed using regenerated cellulose/BaTiO3 (C/BT) aerogel papers based polydimethylsiloxane (PDMS) nanocomposites. Benefiting from the high loading but uniform dispersion of tetragonal BT nanoparticles and the enhanced Young Modulus of the nanocomposites, the PENGs can exhibit a maximum voltage of 15.5 V and a maximum power of 11.8 μW under an external mechanical impact. By introducing a single electrode TENG, an innovative hybridized nanogenerator has been designed and prepared, which combine different mechanical energy harvesting techniques in a single device. Polarized along proper direction of the PENG, the positive coupling effect can efficiently increase the output voltage and power of the hybridized nanogenerator to 48 V and 85 μW, respectively. This research offers new insights into the design and preparation of high output hybridized nanogenerator with simple structure, high flexibility and easy operation.
关键词： Nanocomposites,BaTiO3 nanoparticles,Cellulose,Piezoelectricity,Hybridized nanogenerator,Triboelectricity
更新于2025-09-23 15:23:52
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Nano-BaTiO3 phase transition behavior in coated BaTiO3-based dielectric ceramics
摘要： In this work, the phase structure of BaTiO3 nanopowders produced by the alkoxide-hydroxide and the hydrothermal method, respectively, was systemically investigated. BaTiO3 nanopowders with cubic phase produced by the alkoxide-hydroxide method could transform to tetragonal phase when heated to about 1100oC. Cubic to tetragonal phase transformation behavior of BaTiO3 nanopowders coated with 0.3BZT-0.7BT or 0.03Nb2O5-0.01Co2O3 was studied. The internal stress within core-shell structure was proposed to explain the BaTiO3 phase transformation behaviors. The mismatch of thermal expansion coefficient between core and shell plays a crucial role in cubic to tetragonal phase transformation of BaTiO3. By tuning the composition of shell and the ratio of the shell to the core, the cubic BaTiO3 core can transform to tetragonal phase successfully after sintering at 1100oC in BaTiO3 based ceramics with core-shell structure and it is mainly resulted by the reduced internal stress between the shell and core.
关键词： Phase transitions,BaTiO3 nanopowders,Internal stress.,Core-shell structure
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Hiroshima (2018.5.27-2018.6.1)] 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Control of Leakage Current through BaTiO<inf>3</inf> Film by Cumulative Cycle of Applied Voltage Scanning for ReRAM or Neuromorphic Application
摘要： We found a new phenomenon that shows a large change in leakage current through BaTiO3 (BTO) film with the maximum ratio of 107 to 109 observed in this work by changing cumulative cycle of voltage scan applied on the film capacitor. These leakage phenomena are thought to depend on several factors such as BTO film thickness, concentration of Vo+, bias voltage, its sweep rate and so on, because trapping/detrapping of carrier electron into/from oxygen vacancy would be a competition dependent on their rates and concentrations. These results imply that the leakage current can be controlled by some sequences or protocols of applied voltage scan, leading to use for ReRAM or neuromorphic applications.
关键词： ReRAM,leakage current,resistive switching,BaTiO3,oxygen vacancy
更新于2025-09-23 15:23:52