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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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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