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Iron oxide (Fe2O3) nanoparticles (NPs), graphene nanoplatelets (GNPs), and nanodiamonds (NDs) reinforced poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanocomposites were synthesized by a solvent casting technique. The structure and morphology of synthesized nanocomposites were studied using Fourier‐transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The thermal behavior of polymer nanocomposites (PNCs) was studied by the thermogravimetric analysis and the derivative thermogravimetry. The dielectric measurements were carried out within the temperature range from 40 to 150°C and in the frequency range from 50 Hz to 15 MHz. At 50 Hz, 140°C, the highest dielectric constant of 92.46 was noted, for the PVDF‐HFP + 10 wt% Fe2O3 + 6 wt% GNPs + 3 wt% NDs and the highest dielectric loss tangent has been observed to be 24.75 at 50 Hz, 140°C for the PVDF‐HFP + 10 wt% Fe2O3 + 4 wt% GNPs + 2 wt% NDs. The electromagnetic interference shielding effectiveness (EMI SE) was studied in the X‐band and Ku‐band frequency regions (8–18 GHz). High EMI SE values of 31.60 dB and 34 dB were observed for PVDF‐HFP/Fe2O3/GNPs/NDs nanocomposites with 10 wt% Fe2O3 + 8 wt% GNPs + 4 wt% NDs in X‐band and Ku‐band, respectively. These findings suggests PVDF‐HFP/Fe2O3/GNPs/NDs‐based PNCs as an appealing material for EMI shielding applications. [ABSTRACT FROM AUTHOR]

High performance electromagnetic interference (EMI) shielding materials with ultra‐low density, excellent flexibility with comprehensive nature are highly demanded for wearable electronics, aeronautic, industries, medical, and research facilities. To address these requirements, the metal‐carbon based polymer composites have been fabricated by simple and scalable synthesis techniques. Combining the effect of multiple scattering with absorption, a high shielding efficiency of up to 29 dB for 0.1 mm is achieved. Selective architects of Ag/Cu nanoparticles along with two‐dimensional conducting sheets of MWCNT/rGO form multiple scattering structures in poly(vinylidene fluoride) matrix, prepared by facile solvent cast technique. The paper discusses the preparation of the composites, studies on morphological aspects, and concludes with a study on EMI shielding in the frequency region between 8 and 12 GHz. [ABSTRACT FROM AUTHOR]

The electromagnetic interference shielding performance of metal decorated MWCNT/rGO in flexible polyvinylidene fluoride (PVDF) films has been studied and reported. X-ray diffraction patterns show the presence of metallic nanoparticles that are bound with the carbon reinforcements of the composites. Morphological studies confirm the homogeneous decoration of the metallic nanoparticles in the MWCNTs and reduced graphene oxide (rGO) nanohybrid fillers of the composites. The enhanced electrical conductivity value of the prepared composite films, found to be 4.52 × 10−6 S cm−1 at 1 MHz, is attributed to the facilitation of space charge distribution by the conducting networks upon the incorporation of the metallic nanoparticles. The effective EMI shielding of the polymer nanocomposites, found to be 28.5 dB at 12 GHz upon the incorporation of the metallic nanoparticles in the MWCNT–rGO/PVDF composites, clearly confirms the formation of interconnected networks that reflect as well as absorb the incident electromagnetic radiation. [ABSTRACT FROM AUTHOR]

A polycrystalline BiFeO3 film on Pt/Ti/SiO2/Si was fabricated using the spin coating technique. The film shows diode-like characteristics with and without poling measured under dark conditions. However, it exhibits a switchable photovoltaic effect with light illumination under poled condi- tions. The measured photovoltaic effect revealed an open circuit voltage of ~0.47V and a short circuit current of 3.82 µA/cm² under the illumination of 165 mW/cm² irradiance. The studies clarified the dominant role of the depolarization field rather than the interface in the photovoltaic characteristics of the BiFeO3 film. Significantly, the photo-capacitance effect was demonstrated with a substantial enhancement in capacitance (~45%) in Au/BiFeO3/Pt geometry, which could open up a new window for BiFeO3 applications. [ABSTRACT FROM AUTHOR]

Neutron diffraction under operando battery cycling is used to study the lithium and oxygen dynamics of high Li-rich Li(Lix/3 Ni(3/8-3x/8) Co(1/4-x/4) Mn(3/8+7x/24) O2) x = 0.6, HLR) and low Li-rich Li(Lix/3 Ni(1/3-x/3) Co(1/3-x/3) Mn(1/3+x/3) O2 (x = 0.24, LLR) compounds that exhibit different degrees of oxygen activation at high voltage. The measured lattice parameter changes and oxygen position show largely contrasting changes for the two cathodes where the LLR exhibits larger movement of oxygen and lattice contractions in comparison to the HLR that maintains relatively constant lattice parameters and oxygen position during the high voltage plateau until the end of charge. Density functional theory calculations show the presence of oxygen vacancy during the high voltage plateau; changes in the lattice parameters and oxygen position are consistent with experimental observations. Lithium migration kinetics for the Li-rich material is observed under operando conditions for the first time to reveal the rate of lithium extraction from the lithium layer, and transition metal layer is related to the different charge and discharge characteristics. At the beginning of charging, the lithium extraction predominately occurs within the lithium layer. Once the high voltage plateau is reached, the lithium extraction from the lithium layer slows down and extraction from the transition metal layer evolves at a faster rate. [ABSTRACT FROM AUTHOR]

We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. The impinging jet is designed in a wall-tube configuration, in which the jet diameter is large compared to the electrode diameter, thus providing uniform and rapid mass transfer conditions over the entirety of the electrode surface. This combination of rapid detection and controllable flow conditions allows a wide range of hydrodynamic conditions to be accessed with simultaneous electrochemical and mass spectrometric detection of dissolved gas species, which is important in the analysis of a range of electrochemical reactions. The capabilities of this configuration are illustrated using a platinum-coated electrode and several electrochemical reactions, including ferrocyanide oxidation, proton reduction, and oxalic acid oxidation. [ABSTRACT FROM AUTHOR]

Microwave sintering of materials significantly depends on dielectric, magnetic and conductive losses. Samples with high dielectric and magnetic loss such as ferrites could be sintered easily. But low dielectric loss material such as dielectric resonators (paraelectrics) finds difficulty in generation of heat during microwave interaction. Microwave sintering of materials of these two classes helps in understanding the variation in dielectric and magnetic characteristics with respect to the change in grain size. High-energy ball milled Ni0.6Cu0.2Zn0.2Fe1.98O4-σand ZnTiO3are sintered in conventional and microwave methods and characterized for respective dielectric and magnetic characteristics. The grain size variation with higher copper content is also observed with conventional and microwave sintering. The grain size in microwave sintered Ni0.6Cu0.2Zn0.2Fe1.98O4-σ is found to be much small and uniform in comparison with conventional sintered sample. However, the grain size of microwave sintered sample is almost equal to that of conventional sintered sample of Ni0.3Cu0.5Zn0.2Fe1.98O4-σ. In contrast to these high dielectric and magnetic loss ferrites, the paraelectric materials are observed to sinter in presence of microwaves. Although microwave sintered zinc titanate sample showed finer and uniform grains with respect to conventional samples, the dielectric characteristics of microwave sintered sample are found to be less than that of conventional sample. Low dielectric constant is attributed to the low density. Smaller grain size is found to be responsible for low quality factor and the presence of small percentage of TiO2 is observed to achieve the temperature stable resonant frequency. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) films have been used as counter electrodes in natural dye-sensitized (anthocyanin-sensitized) solar cells to improve the cell performance. Compared with conventional cells using natural dye electrolytes and platinum as the counter electrodes, cells with a single-walled nanotube (SWNT) film counter electrode show comparable conversion efficiency, which is attributed to the increase in short circuit current density due to the high conductivity of the SWNT film. [ABSTRACT FROM AUTHOR]

Development of materials and structures leading to lithium ion batteries with high energy and power density is a major requirement for catering to the power needs of present day electronic industry. Here, we report an in situ formation of a sandwiched structure involving single-walled carbon nanotube film, copper oxide, and copper during the direct synthesis of nanotube macrofilms over copper foils and their electrochemical performance in lithium ion batteries. The sandwiched structure showed a remarkably high reversible capacity of 220 mAh/g at a high cycling current of 18.6 A/g (50 C), leading to a significantly improved electrochemical performance which is extremely high compared to pure carbon nanotube and any other carbon based materials.