Journal of Electronic Materials最新文献

This study investigates the effect of particle concentration on tuneable magneto-optical transmittance and optically induced refractive index coefficients in Fe₃O₄-based nanomagnetic fluid (NMF) at room temperature. A static magneto-optical experimental setup was devised to investigate the magneto-optical effects arising from variations in particle concentration and dipolar interactions, under varying magnetic fields. In this work, Fe₃O₄-based nanomagnetic fluid was synthesized using a chemical co-precipitation method. The structural, morphological, and magnetic properties of the fluid were investigated using sophisticated characterization techniques including x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and vibrating-sample magnetometry (VSM). Our investigation focused on the tunability of magneto-optical transmittance as a function of the varying magnetic field at different particle concentrations. Further, we observed variations in diffraction fringes in the nanomagnetic fluid, correlating with particle concentration, by passing a high-power laser through the diluted fluid system. Light–matter interaction in the presence of a varying magnetic field induces optical anisotropy in the fluid, whereas dipole–moment interaction and magnetic particle alignment in the presence of a magnetic field are the main supporting phenomenon of magneto-optical tunability in our experiment. Experimental modulation of the transmittance profile and field-induced refractive index coefficients in NMF, elucidated through fringe diffraction, has potential for applications such as tuneable magneto-optical devices, optical filters, and optical limiters.

A theoretical investigation is conducted on semiconducting MXenes (hbox {M}_{2})COS (M = Zr, Hf) using both density functional theory and the Boltzmann transport equation. The findings suggest that optimization of thermoelectric properties is more effective through n-type doping than p-type doping. At 300 K, n-type doping yields a power factor of 4.3(times ) 10(^{3}) (mu )W/(hbox {mK}^{2}) for Zr({_2})COS and 4.5(times ) 10(^{3}) (mu )W/(hbox {mK}^{2}) for Hf({_2})COS. Furthermore, lattice thermal conductivity ((kappa _{l})) values of 21.8 W/m K and 27 W/m K are obtained for Zr({_2})COS and Hf({_2})COS, respectively, at 300 K. These values are lower than the lattice thermal conductivity of oxygen-functionalized MXenes (hbox {Zr}_2hbox {CO}_2) (61.9 W/m K) and (hbox {Hf}_2hbox {CO}_2) (86.3 W/m K). The projected thermoelectric figure of merit value can potentially reach 0.27 and 0.23 at 700 K for n-type Zr({_2})COS and Hf({_2})COS, respectively. These findings reveal the promising application prospects for n-type Zr({_2})COS and Hf({_2})COS in the field of thermoelectric materials.

A graphene oxide (GO)-based humidity sensor is reported in this work wherein the influence of the substrate on its humidity-sensing properties is compared by depositing a GO film on two different substrates: glass and wearable fabric. While the GO film exhibits sensitivity to humidity for both substrates, its response varies from 35% for the glass substrate to 74% for wearable fabric at 60% relative humidity (RH), clearly indicating the superiority of the wearable fabric over glass. The sensors (on both substrates) show almost no sensitivity to several common volatile organic compounds (VOCs) and gases, suggesting their high selectivity towards humidity. In both cases, the sensor can detect humidity with high repeatability over several cycles and exhibits fast response and recovery times of 6 s/10 s and 7 s/12 s for glass and wearable fabric, respectively. The sensing mechanism is explained in terms of pre-adsorbed surface oxygen ions, as measured by the change in water signal upon exposure of the GO film to humidity using Fourier transform infrared (FTIR) spectroscopy. Thus, we demonstrate that the developed GO film on wearable fabric can act as a low-cost, flexible, and wearable humidity sensor with good sensitivity, reproducibility, and selectivity.

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Due to the imperative development of vibrational energy utilization in wireless sensing, power supply for microdevices, energy storage, etc., energy harvesters and their efficiency are highly regarded by researchers. With the introduction of nonlinearity, the shortcomings such as narrow working frequency range, low power output, and high start-up threshold from linear energy harvesters were significantly improved and aroused a great increase in applications. In a broad sense, we usually classify energy harvesters as piezoelectric energy harvesters (PEH) and non-piezoelectric energy harvesters, which can be further classified into electromagnetic, triboelectric, and electrostatic energy harvesters. The development of energy harvesters with nonlinearity from the most cited literature in recent years and the trends have been reviewed in this paper. Systematic theoretical study, research of energy-harvesting materials, new methods for efficiency enhancement, circuits, and specific applications with energy harvesters have also been summarized and discussed for electromagnetic waves. This paper provides a brief reference for relevant scholars to understand the current development status, and trends of energy harvesters with nonlinearity.

Core–shell nanoparticles were synthesised by coating copper over CuS nanoparticles, which were synthesised using different precursors. X-ray diffraction, x-ray photoelectron spectroscopy (XPS) and field-emission electron microscopy (FESEM) analysis showed the variation in crystallite size, chemical state, and morphological properties. The band gap was in the range of 1.32–2.08 eV for coated and uncoated samples. The emission peaks in photoluminescence spectra showed the presence of defects, and all analyses were correlated with each other to explain the 95% degradation of 50 ml rhodamine blue dye at a concentration of 1 mg/L in 60 min using the catalytic weight of 15 mg. The plasmonic properties were observed in near-infrared (NIR) absorption analysis and explained with the help of XPS and its enhancement in photocatalytic activity. The coating of copper over copper sulphide nanoparticles in sample 1-C and 2-C showed improved catalytic degradation for rhodamine blue.

Graphical Abstract

In this work, we present and report on the evolution of thermoelectric properties altered through changes in the energy barrier height in thermally evaporated mixed-phase copper sulfide thin films. The physical interpretations depend on the conception of degenerate energy levels near the top of the valence band. The energy barrier at grain boundaries was highlighted and assumed to be the origin of the rapid evolution of the conductivity and Seebeck coefficient of the film annealed at 723 K. The position of the energy levels of the active carriers with respect to the Fermi energy reinforces the effect of annealing temperature on the Seebeck coefficient and electrical conductivity and was observed to transform the system from a system with fully ionized impurities to a system with impurities that are not fully ionized, which enhances the barrier height. The evolution of the Seebeck coefficient is explained in terms of thermal activation. The sample annealed at 623 K exhibited the lowest barrier height of 32 meV, with an activation energy of 111 meV. The sample annealed at 673 K had a barrier height of 46 meV with an activation energy of 136 meV. Finally, the sample annealed at 723 K exhibited a barrier height of 103 meV, which explains its relatively high room-temperature Seebeck coefficient, with a pronounced effect of temperature.

As wearable electronic devices advance, there is a growing demand for stand-alone flexible thermoelectric materials and devices capable of harvesting low-grade thermal energy from human skin. The polar molecule DMSO is known to enhance the electrical properties of PEDOT, with the underlying mechanism believed to involve structural changes in PEDOT that improve carrier mobility, although carrier concentration has a more pronounced effect on conductivity. In this study, we examined the impact of varying DMSO concentrations on PEDOT. With the optimal addition of DMSO (10 vol.%), PSS and PEDOT were effectively separated, resulting in parallel lamellar microstructures that improved the continuity of the conductive network. Hall effect measurements showed significant increases in both carrier concentration and mobility. The PEDOT⁺ polaritons were arranged parallel to the lamellar structure, facilitating rapid charge transport along the molecular chains. This arrangement led to enhanced three-dimensional charge transfer, increased π-π conjugate stacking between microstructural layers, and a greater electron cloud density. The synergistic effect of these changes resulted in a three-fold increase in film conductivity. Additionally, lightly doping PEDOT with DMSO led to a 35% increase in the Seebeck coefficient with rising operating temperatures. The resulting free-standing, flexible films, characterized by low thermal conductivity and high electrical conductivity, are well-suited for use in miniature flexible sensors or wearable electronic devices.

Polycrystalline ceramics with the composition 0.45BaTi_0.80Zr_0.20O₃-0.55Ba_0.69Ca_0.30Sm_0.01Ti_0.99Fe_0.01O₃ were prepared using the solid-state reaction route. The phase formation of the prepared sample was confirmed by x-ray diffraction (XRD) study. The temperature-dependent dielectric permittivity (ε) showed a diffuse phase transition. The observance of ferroelectricity at temperatures above the Curie temperature (T_C) suggests the presence of nano-polar regions in the sample. The efficiency (ƞ), recoverable energy density (W_rec), and loss (W_loss) were determined from the P–E loops. The efficiency (ƞ) increased with an increase in temperature, while W_loss showed a reverse trend. The measured value of W_rec was 0.10 J/cm³, and a value of 94% was found for ƞ. The electrocaloric effect (ECE) was studied using the indirect method, and an adiabatic change in temperature (ΔT) of 0.34 K was found at 25 kV/cm with an electrocaloric coefficient = 0.0136 K cm kV⁻¹. These results suggest that this composition can be used in energy storage and electrocaloric applications.

Photocatalytic degradation is vital to combat water pollution, utilizing sunlight to degrade organic contaminants. Bismuth ferrite (BFO), a multiferroic, is particularly effective as a photocatalyst as it can be magnetically recovered and reused. This study presents a comprehensive investigation into the photocatalytic degradation of organic dyes using BFO nanoparticles (NPs) synthesized through a sol–gel method. Degradation studies are conducted under different pH conditions (neutral, acidic, or basic) and using both cationic (methylene blue and malachite green) and anionic (methyl orange and Congo red) dyes under controlled photocatalytic conditions. Our findings reveal that cationic dyes show enhanced degradation in basic conditions, whereas anionic dyes are more effectively degraded in acidic conditions. The BFO NPs are magnetically recovered from the solution with approximately 98% efficiency and subsequently reused for dye degradation. This study demonstrates the potential of BFO NPs in photocatalytic applications paving the way for future research towards environmental clean-up.

Graphical Abstract

WO₃ is considered to be significant for diverse applications such as gas sensing, photocatalysis, and photovoltaic devices because of its wide optical band gap. Ion beam treatment of various metal oxides produces defects that modify various properties including the morphological, structural, and optical properties of the metal oxides. When the energetic ions cross through the target materials, two kinds of energy losses occur, i.e., nuclear and electronic energy loss. In high-energy ion beam treatment of thin films, electronic energy loss is dominant over nuclear energy loss. In our current study, thin films of tungsten oxide were grown on a substrate of glass and silicon by the radio frequency (RF) sputtering method. The sputtered WO₃ thin films were exposed to an ion beam of Ag ion with an energy of 120 MeV at various fluence levels of 1.0 × 10¹² ions/cm², 5 × 10¹² ions/cm², and 1.0 × 10¹³ ions/cm². Optical study revealed changes in the energy band gap of ion-irradiated WO₃ thin films. From Raman spectroscopy, the phase observed was monoclinic for pristine and irradiated samples. PL spectroscopy of the pristine and ion beam-implanted WO₃ thin films showed emission spectra at a wavelength 437 nm with an excitation wavelength of 420 nm. X-ray photoelectron spectroscopy showed the presence of W and O atoms and showed changes in the electronic structure after Ag ion beam irradiation.