Journal of Advanced Dielectrics

Journal of Advanced Dielectrics, Ahead of Print. <br/> In this work, conductor MXene (Ti3C2Tx), ferroelectric Bi[math]Na[math]Nb5O[math] (BNN) and NaNbO3 (NN) modified P(VDF-TrFE) piezoelectric composite films were prepared by electrostatic spinning. A uniaxial intermittent alternating dual-spray method was used to construct component-layered P(VDF-TrFE)-based composite films, i.e., NN-MXene-NN-MXene, BNN-MXene-BNN-MXene and BNN-NN-BNN-NN. The results indicated that the 4[math]wt.% BNN-P(VDF-TrFE) composite film exhibited the best comprehensive performance. The piezoelectric output performance of 4-BNN reached 15.18[math]V, which was a remarkable increase of 236.59% over the baseline value of 4.51[math]V without any doping. The 4-BNN composite film exhibited superior mechanical and electrical properties, with a tensile strength of approximately 15.68[math]MPa and an elongation at break of 301.41%, representing an increase of 147.67% and 262.03% compared to P(VDF-TrFE). Furthermore, the film demonstrated good stability, sensitivity and hydrophobicity. When connected to a load of [math], the current in the circuit was approximately 2.88[math] [math]A, and the maximum power was 2.07[math] [math]W/cm2. Additionally, the piezoelectric nanogenerator (PENG) was prepared using 4[math]wt.% BNN-P(VDF-TrFE) composite film to demonstrate sensing properties of body movement.

Journal of Advanced Dielectrics, Ahead of Print. <br/> Dielectric spectra of protective organic films at different mechanical pressures in the frequency range of [math] [math]Hz have been experimentally investigated. The films were obtained on the surface of rolled steel from a unimolar solution of sulfuric acid using a new organic compound of the imidazole class as an inhibitor by varying the adsorption time of the additive and its concentration. The films are characterized by the presence of negative electrical capacitance and high through conductivity. Three dielectric dispersions are observed in the spectra, two of which have a relaxation character and one of which is resonant. The negativity of the electrical capacity of the investigated films is apparently due to three factors: High-frequency relaxation and resonance processes in electric fields with inverse field strength and low-frequency hopping-type conduction processes. To interpret the high-frequency relaxation polarization with inverse electric field strength, an impedance model of an organic film sample is used in the form of an equivalent current divider circuit consisting of series and parallel RC circuits. The comparison of experimentally measured electrical parameters of various films with approximated results within the framework of the described model showed their good agreement.

Journal of Advanced Dielectrics, Ahead of Print. <br/> The degradation of optoelectronic properties due to light-induced phase segregation in mixed-halide perovskites presents a major challenge for their future commercial applications. However, the mechanism behind their phase separation behavior under continuous illumination or high temperature is still under debate. Here, we systematically measure the phase separation reversal behavior of CsPbI[math]Br[math] polycrystalline films under photo-thermal cycling. The distribution of halide ions on the film surface corresponded to the phase separation caused by the number of cycles by confocal laser microscope. It was observed that the uniform dots formed at the grain boundary under photothermal cycling were attributed to the oxides generated by light. Finally, according to the optical thermal cycle phenomenon, a low-cost, contactless read-write and erase optical memory is developed, which provides an opportunity for the use of mixed halide perovskite in optical memory applications.

Journal of Advanced Dielectrics, Ahead of Print. <br/> Pure and superstoichiometric modified by 2[math]wt.% Bi2O3 and 2[math]wt.% manganese oxide (Mn2O3) ceramic samples of the binary system 0.71BiFeO3-0.29BaTiO3 were fabricated using conventional ceramic technology by double solid-phase synthesis with following sintering. Mechanical activation of synthesized powders was carried out at the stage of manufacturing press powders prepared for sintering. X-ray analysis at room temperature showed that all studied ceramics have pseudo-cubic symmetry. Grain morphology, dielectric and piezoelectric properties of selected solid solutions were investigated. The modification increased the homogeneity of the material, dielectric constant and piezomodulus [math] and also resulted in a decrease in the dielectric loss tangent. The highest piezoelectric coefficient [math] [math]pC/N was obtained. Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior and region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 740–770[math]K.

Journal of Advanced Dielectrics, Ahead of Print. <br/> This paper demonstrates the influence of deposition parameters (temperature, power and time) and stoichiometric composition of thin aluminum nitride (AlN) coatings, the thickness of which varied from 320 to 1100[math]nm deposited by DC reactive magnetron sputtering on their microstructure, mechanical and microtribological properties. The investigation revealed that high-deposition power (150[math]W) and temperature ([math]C) lead to sputtering of coatings with high roughness, low mechanical and high microtribological properties. Such a phenomenon occurred due to the formation of a coarse-grained structure, high porosity and dendritic growth of the coating, which was observed on their cross-sections. Reducing the deposition temperature to [math]C and power to 80–100[math]W allowed to obtain a fine-crystalline structure demonstrating low-roughness values with crystallites evenly and compactly distributed over the surface. Such coatings showed higher mechanical and low microtribological properties. Surface resistivity was lower on coatings with a fine crystalline structure and correlated with the nitrogen content of the coating. In the course of the research, it was demonstrated that the optimal combination of microstructure, mechanical, microtribological properties and electrical resistivity for practical use in micro- and nanosensory applications may be achieved for the AlN coating with the thickness of 320[math]nm and 29.71[math]at.% N, deposited at [math]C, 100[math]W and 20[math]min. Such a coating possesses the highest values of mechanical properties, low roughness and specific surface resistance, as well as low coefficient of friction and specific volumetric wear compared to all coatings under study.