In this study, we introduce a single/few-layered graphene oxide (GO) synthesized with ultrasonication, and demonstrate its high dielectric permittivity in the frequency range of 20 Hz to 2 MHz and temperature range of 30 C to 180 C. A high dielectric constant of GO ($10 6 ) with low loss was observed at 1 kHz and at 30 C, which is even very high compared to conventional dielectric materials such as CaCu 3 Ti 4 O 12 . The conductivity of our GO was calculated and found to be 3.980 Â 10 À5 to 1.943 Â 10 À5 (DC) and 2.0 Â 10 À3 to 1.7 Â 10 À2 (AC). The various conducting mechanisms governing the conductivity (AC and DC) of GO with varying frequency and temperature are assessed using impedance spectroscopy. The mechanistic approach and the role of functional groups, defects, temperature and frequency are elucidated and discussed with regard to the high dielectric constant. The variation of activation energy from 1.15 (1 kHz) to 0.58 (2.0 MHz) is related to the frequency dependent conductivity of the p-p conjugated electrons and their hopping has also been discussed. The present dielectric results are superior to those of GOL (with fewer defects/less sonication time). Moreover, the present findings suggest that the new GO can be used for scaling advances high performance electronic devices and high dielectric-based electronic and energy storage devices.

This paper covers the core-shell nanomaterials, mainly, polymer-core polymer shell, polymer-core metal shell, and polymer-core nonmetal shells. Herein, various synthesis techniques, properties, and applications of these materials have been discussed. The detailed discussion of the properties with experimental parameters has been carried out. The various characterization techniques for the core-shell nanostructure have also been discussed. Their physical and chemical properties have been addressed. The future aspects of such core-shell nanostructures for biomedical and various other applications have been discussed with a special emphasis on their properties.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adom.201900958. 2−y 2 , d z 2 ) levels. [35] The splitting of the d-orbital was successfully explained by the crystal field theory. The ground state properties of these materials are mainly governed by the two interactions; i) the electron correlations (U) and, ii) SOC (λ) in the crystal field split narrow bands. [36] Among d electron systems, electrons in 3d TMOs experiences large electron correlations due to localized nature of 3d orbitals. The idea of electron-electron interaction was given by Sir N. F. Mott in 1949. It originated from the fact that the NiO was expected to be a metal according to the band theory, while the experiments showed insulating behavior. [37][38][39][40][41] This disagreement of experiments with the theory was explained by Hubbard who attributed the insulating state to the splitting

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Self-assembled and surface decorated PANI nanotubes with rectangular hallow core with high electrical and dielectric properties.

The metal-insulator transition (MIT) in correlated systems is a central phenomenon that possesses potential for several emerging technologies. We investigate the kinetics of such MIT in perovskite nickelates by studying the terahertz (THz) low-energy charge dynamics in orthorhombic and tetragonal symmetries of Pr0.5Nd0.5NiO3 thin films. The THz conductivity of the orthorhombic thin film is dominated by Drude behavior in the entire temperature range, albeit a dominant anomaly at and around the MIT region. The tetragonal thin film exhibits different overall THz conductivity dynamics though, i.e. of a Drude–Smith (DS) type in the entire temperature range, the DS coefficient signifying dominant backscattering peaks in the MIT region. While the overall THz dynamics profile is different for the two films, a unique yet similar sensitivity of the I–M transition regions of both films to THz frequencies underlines the fundamental origin of the bi-critical phase around MIT of the nickelates. The peculiar behavior around the I–M transition, as evaluated in the framework of a percolative path approximation based Dyre expression, emphasizes the importance of critical metallic volume fraction (fc) for the percolation conduction, as an fc of ~0.645 obtained for the present case, along with evidence for the absence of super-heating.

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The bulk rhombohedral LaNiO3 is a unique member of the rare-earth nickelate RNiO3 family devoid of any phase transition down to low temperatures, in addition, it lies in the proximity of quantum critical point. In this paper, we show that the bi-axial strain induces pronounced disparity both in static and dynamic transport when measured across two in-plane crystal axes of an orthorhombic LaNiO3 thin film. A maximum in-plane transport anisotropy of 50% at 30 K is observed in dc conductivity when measured across [1 0 0]o and [0 1 0]o directions. Similar in-plane dynamic transport anisotropy i.e. dissimilar disorder strengths appear across two orthogonal axes in oxygen deficient film. In oxygen stoichiometric film too, a pure Drude-type THz conductivity transforms to a near Drude-type across in-plane orientations. This unique in-plane transport anisotropy, unveiled in a broad range of dc to THz frequencies, underlines a strong structure-property relation and emphasizes the need to engineer the charge transport along appropriate crystal axis for evaluating the application potential of rare earth nickelates.