This work studies the direct current breakdown characteristics of unfilled epoxy and epoxy nonconductive nanocomposites (${\mathrm{S}\mathrm{i}\mathrm{O}}_2,\mathrm{M}\mathrm{g}\mathrm{O}$ and ${\mathrm{A}\mathrm{l}}_2{\mathrm{O}}_3$). It also examines the variation of electrical properties in epoxy nanocomposites. The novel aspect of this study is that the samples of Epoxy nanocomposite were exposed to high voltages of up to six kilo volts for three hours using field electron microscopy under high vacuum conditions (${10}^{-5}$ mbar). The current emitted from these samples was measured at three different intervals of time. In addition, the influence of high voltage on the permittivity, loss factor (tan(δ)), and conductivity of the epoxy nanocomposite was studied. This evaluation was conducted before and after applying the voltage at room temperature, The frequency range extends from ${10}^{-2}$–${10}^{-7}$ Hz using the Novo Control Alpha-A analyzer. Current–voltage characterization was performed through field electron microscopy. The samples were characterized by scanning electron microscopy–energy dispersive X-ray spectroscopy and Fourier Transform Infrared Spectroscopy. The unfilled epoxy exhibited structural degradation, resulting in the formation of holes when exposed to high voltages of up to six kilo volts, leading to a reduction in electrical properties. Nevertheless, the addition of nanoparticles shows a significant increase in the operational lifetime of the epoxy nanocomposite. The degree of increase in the lifetime of epoxy composite varied depending on several factors such as the type of NPs introduced and their respective sizes. The epoxy/${\mathrm{A}\mathrm{l}}_2{\mathrm{O}}_3$ nanocomposite comparing with epoxy/MgO and epoxy/${\mathrm{S}\mathrm{i}\mathrm{O}}_2$ nanocomposite showed elevated resistance to direct current breakdown strength and maintaining its dielectric.

High-entropy oxides (HEOs) are considered promising materials in many electrical applications, especially in the fields of batteries, energy storage and conversion, and catalysis. The study material, (CoCrFeNiMn)₃O₄ in particular, has been shown to possess gigantic capacitance, a characteristic that emanates from its oxide precursors properties. The material was successfully prepared using the solid-state reaction method, as the material showed structural stability despite its different composition and the possibility of controlling its magnetic properties based on its composition, as the saturation value of Fe excessive addition-S2.Fe reached 52 emu/g, with it having a relatively high coercivity value, which is estimated at 1102.47 Oe. It was also observed that electron hopping between different oxidation states is based on the high-resolution X-ray photoelectron spectroscopy (XPS) results, which has a role in the magnetic properties.

Graphite-based microcathodes have shown significant performance when operated as cold field emission electron sources. Specifically mentioned, cathodes that have been prepared from highly ordered pyrolytic graphite and polymer graphite pencil leads. Such cathodes are characterized by low operating voltages, a long lifetime, a cheap fabrication price, and a stable emission current. Recently, it was shown that polymer graphite cold field emission cathodes have a unique quasi-harmonic field emission behavior, where the process included emission of pulses of electrons with relatively higher emission current values. However, this behavior has not been reported for other graphite-based materials. In this paper, we study the effects of the polymer binding agent on the charge carriers’ flow through the surface of polymer graphite using Raman-current spectroscopy. The results from polymer graphite were then compared to cathodes prepared from colloidal graphite conductive paint when deposited on a glass substrate. The results showed that the I(D)/I(G) ratio of polymer graphite had a fluctuating behavior, which was not the case for colloidal graphite, which had a more stable structure.