Dielectric Constant Research Articles

Three-Dimensional Covalent Organic Frameworks with lil Topology.

The diversity of covalent organic frameworks (COFs) is continuously expanding, providing various materials with tailor-made structures and properties. However, the development of crystalline three-dimensional (3D) COFs with new topologies is an essential but arduous challenge. In this study, we first developed one kind of 3D COFs with the lil topological structure, which were assembled by D4h- and C2h-symmetric building blocks. The 3D COFs were determined in a space group of Imma, in which each D4h-symmetric unit is connected with four C2h-symmetric units, forming a noninterpenetrated network. The densely packed copper phthalocyanine and stable polyimide linkage render these COFs as a polymeric material with high dielectric constant and low dielectric loss at high frequencies (>1 kHz). Significantly, the dielectric constant was determined as high as 63, which constitutes a new record value among phthalocyanine-based and polyimide polymers. Therefore, this study not only provides important guidance for the design of 3D lil-net COFs but also supplies promising materials for application in high-energy-density and pulsed capacitors.

Understanding the impact of plasma functionalized MWCNTs on the structure, physicochemical and mechanical properties of PEMA

In this study, plasma functionalized multiwalled carbon nanotubes, f-MWCNTs, were incorporated into a poly(ethyl methacrylate), PEMA, polymer matrix at different wt.% (0.005, 0.01, and 0.02 wt.%) to prepare nanocomposite films using the traditional solution casting method. The XRD, Raman spectroscopy, XPS, TGA, mechanical analysis and UV–Vis spectroscopy techniques were employed to investigate the effects of the wt.% of f-MWCNTs on the structure, spectroscopic and other physiochemical properties of the synthesized films. XRD analysis showed a monotonic change in the PEMA structure upon incorporation of f-MWCNTs at different wt.%. The XPS results showed an increase of oxygen-based functional groups C-O and O-C-O on the PEMA/f-MWCNTs/ composite films compared to pure PEMA. Raman spectroscopy results consistent with the XRD and XPS findings, confirming the homogeneous distribution of f-MWCNTs in the PEMA matrix. Thermal stability of f-MWCNTs/PEMA improved as the f-MWCNTs content increased. Optical studies showed a reduction in the bandgap energy as the f-MWCNTs content increased, accompanied by significant improvements in optical properties such as refractive index (n), extinction coefficient (k), dielectric constants (ε′ and ε″), and optical conductivity (σopt). Mechanical testing revealed enhancements in breaking strength, Young’s modulus, yield stress, and elongation at break with increasing f-MWCNTs concentrations. Furthermore, the AC electrical conductivity of the films also improved, demonstrating better charge transport capabilities. These synergistic enhancements in optical, thermal, mechanical, and electrical properties make PEMA/f-MWCNTs nanocomposites promising candidates for advanced applications, including optoelectronic devices, optical components, and conductive packaging materials.

GRAIN SIZE-MOLAR RATIO EFFECTS ON MAGNETO-ELECTRIC PROPERTIES IN PB(ZR0.52TI0.48)O3/COFE2O4 PARTICULATE MULTIFERROIC COMPOSITES BY MICROWAVE OVEN SINTERING

This study aims to investigate the electric, magnetic, and magnetoelectric properties for the lead zirconate titanate-cobalt ferrite particulate multiferroic composite, Pb(Zr0.52Ti0.48)O3/CoFe2O4.The composites were synthesized utilizing the Pechini method and thermally sintered employing a microwave oven and a conventional method. Two molar ratios, 80/20 and 50/50, of the constituents' phases were utilized to analyze the effect of grain size on properties. The results of X-ray diffraction (XRD) patterns indicated no formation of secondary phases for powder phases and ceramic composites. The micrographs exhibited the distribution of magnetic grains in the ferroelectric matrix and displayed 0-3 connectivity. The dielectric constants, electric resistivity, and ferroelectric properties demonstrated a decrease in their values between approximately 10% and 20% for composites sintered by the microwave-oven method, which was attributed to the decrease in the grain size of the ferroelectric phase and the molar increase of the magnetic phase, resulting in electrical losses due to the presence of a non-ferroelectric phase. The magnetic hysteresis and magnetostriction coefficients exhibited higher values for the microwave-oven method than the conventional method as the magnetic anisotropy effect is more pronounced for smaller ferrite grain sizes. The induced voltage via magnetoelectric coupling was observed for all composites. The composites produced by microwave sintering (MS) exhibited higher voltage values than those produced by conventional sintering (CS). However, the magnetoelectric coefficients for composites with a 50/50 molar ratio were lower than those with an 80/20 molar ratio, which was potentially attributed to the reduction in ferroelectric grain size and increased electrical losses. Consequently, these results demonstrate a novel approach to improve performance and potential applications for functional devices.

Interface engineering of 2D dielectric nanosheets for boosting energy storage performance of polyvinylidene fluoride-based nanocomposites with high charge-discharge efficiency.

Polyvinylidene fluoride (PVDF) film, with high energy density and excellent mechanical properties, has drawn attention as an energy storage device. However, conduction loss in PVDF under high electric fields hinders improvement in efficiency due to electrode-limited and bulk-limited conduction. Well-aligned multilayer interfaces of two-dimensional (2D) nanocoatings can block charge injection, reducing electrode-limited conduction loss in dielectric polymers. Thus, rational selection of 2D fillers is crucial for designing high-energy-density dielectric materials. This study explores 2D oxide nanosheets with varying dielectric constants and bandgaps, such as Ti0.87O2, Ca2Nb3O10, and montmorillonite (MMT). Ca2Nb3O10 nanosheets, with a higher dielectric constant and similar bandgap to Ti0.87O2, created a higher Schottky barrier (0.6 eV), resulting in a discharge energy density (Ud) of 26.4 J cm-3 at 720 MV m-1 in PVDF-Ca2Nb3O10 film. The PVDF-MMT film, coated with MMT nanosheets featuring a lower dielectric constant yet a higher bandgap, achieves a similar Ud of 26.8 J cm-3 at 720 MV m-1, with efficiencies (η) above 80% for both films. The results indicate that the bandgap and dielectric constant of 2D nanosheets play a crucial role in determining PVDF composites' energy storage density and efficiency, necessitating a balance between these parameters. Furthermore, ultraviolet (UV) irradiation was introduced to induce trap centers and inhibit charge conduction and energy loss in PVDF-based composites under high electric fields. Consequently, the UV-treated PVDF-MMT composite film achieves a Ud of 29.1 J cm-3 and an η of 78.3% at 750 MV m-1. This work offers an effective strategy for developing high-energy density, high-efficiency PVDF-based polymer materials.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ДИЭЛЕКТРИЧЕСКИХ СВОЙСТВ ПЕРЕРАБОТАННЫХ ЗЕРНОВЫХ

The purpose of research is to study the dielectric properties of grains processed by mechanical activation using the example of wheat, barley and oats, which are widely used in the agro-industrial complex and the food industry. Objective: to identify the relationship between the dielectric parameters of processed grain and its structural parameters (fraction size) in a wide range of variations in the external electric field from 50 Hz to 1 KHz, which may be useful in optimizing grain processing technologies and choosing optimal storage conditions. A series of experiments was carried out for samples of wheat, oats and barley, varying the degree of fractions from 50 to 1000 μm in a wide frequency range. An algorithm has been developed for calculating dielectric constant and dielectric loss tangent based on measurements of electrical capacitance and conductivity using a certified E7-20 voltage immittance meter and a measuring cell (flat capacitor). An analysis of variations in electrical capacitance, the real part of dielectric constant, electrical conductivity and dielectric loss tangent on the particle size of grain crops was carried out. It has been established that there is a correlation between the dielectric properties of grain processed by mechanical activation and the size of the fractions, which is most significant for small-sized samples with a particle size of no more than 250 microns. A smoothing of variations in dielectric constant and losses was noted as the electric field frequency increased above 100 Hz. The existence of a relationship between the energy properties of the studied fine heterogeneous medium and the degree of grinding in the frequency range under study has been experimentally confirmed. An optimal size for grain processing has been proposed, which will, along with saving energy resources, allow optimizing energy value, improving the quality of food products and the efficiency of agricultural production in general.

Wood Bark-Based Films as Electrical Insulators with Ultralow Dielectric Constant and Loss Factor.

Dielectric polymers, particularly thermally stable synthetic types, play a crucial role in capacitors, circuit boards, insulators, and high-frequency devices. However, they also contribute significantly to electronic waste, making up approximately 20% of the 74.7 million metric tons of e-waste generated each year. Unfortunately, less than 18% of this waste is properly recycled, posing serious risks to human health and the environment. To address these challenges, we present a circular approach to fabricating biobased dielectric structures with ultralow dielectric constant and dielectric loss factor. Our method utilizes forestry residues derived from birch bark, after the extraction of high-value bioactive compounds. Specifically, we process the thermally stable, lignin-rich fibers in the residual bark through partial dissolution and cross-linking to produce "birch dielectric (BD)" films. These films exhibit exceptional dielectric properties, with dielectric constant (Dk) and loss factor (Df) values as low as ∼1.8 and ∼0.002, respectively, outperforming or matching the requirements of modern electrical insulators, including advanced polymer blends based on polyimides. In addition to their functional performance, BD films demonstrate remarkable mechanical and thermal stability, photothermal conversion capabilities, strength retention after cycling, and biodegradability. These findings, supported by experimental data and simulation studies of intermolecular interactions, highlight the potential of BD films as a sustainable and efficient alternative to conventional dielectric materials.

Influence of fiber concentration and length on the dielectric, mechanical, and thermal properties of maple wood fiber-reinforced polypropylene

Natural fiber-reinforced polymer composites are gaining popularity due to their sustainability and enhanced properties compared to pure polymers. Recently, these composites have been utilized as dielectric materials. In this study, polypropylene (PP) reinforced with maple wood fibers of different lengths (50, 75, and 100 µm) and various fiber concentrations (5%, 10%, 15%, and 20%) were examined. The effects of fiber length and concentration on the dielectric, mechanical, and thermal properties were investigated. All composites exhibited a higher dielectric constant and conductivity than pure PP, along with a lower loss factor. This suggests that adding maple wood fibers generally enhances the dielectric properties. As fiber concentration increases, the dielectric constant tends to rise while the loss factor tends to decrease. TGA results indicated that adding more fibers reduces thermal stability at low temperatures but increases stability at high temperatures. Mechanical testing revealed an increase in strength but a decrease in elongation. However, fiber length did not significantly impact the mechanical properties. SEM analysis showed a uniform distribution of fibers at 5% weight that improves strength, while a 20% weight leads to clustering that weakens the composite.

Dielectric properties of functionalized natural fiber reinforced electromagnetic composite with reduced graphene oxide nanofiller for microwave absorption

AbstractThe integration of 5G technology with advanced electronic devices has intensified electromagnetic pollution concerns, necessitating materials capable of mitigating electromagnetic interference (EMI). This has spurred the development of sustainable alternatives, surpassing conventional synthetic and ferrite materials. Natural fibers, when combined with nanomaterials, exhibit unique properties suitable for EMI shielding. Sugarcane bagasse fiber (SBF), in conjunction with nanofillers such as reduced graphene oxide (rGO), provides a sustainable, lightweight, and eco‐friendly solution for absorbing electromagnetic waves. This study explores the effects of SBF particle size and rGO integration on dielectric and microwave absorption properties. Experimental findings highlight that the EPSB150@1%rGO composite (150 μm SBF with 1 wt% rGO) achieved a maximum dielectric constant (ε′) of 6.62 at 8 GHz, outperforming EPSB@1%rGO (ε′ = 5.45), indicating enhanced charge storage. The dielectric loss (ε″) peaked at 0.41 for EPSB@1%rGO, reflecting superior energy dissipation from interfacial polarization. Reflection loss (RL) calculations revealed improved microwave absorption of −20.07 dB at 12.4 GHz for EPSB150@1%rGO, compared to −15 dB for EPSB@1%rGO, signifying effective EM wave attenuation. These results demonstrate that reduced SBF particle size combined with rGO incorporation significantly enhances dielectric and microwave absorption properties, establishing these composites as promising candidates for EMI shielding and stealth technologies.Highlights 5G technology raises EMI pollution, needing sustainable shielding materials. Sugarcane fiber combined with rGO forms eco‐friendly EMI shielding composite. EPSB150@1%rGO max ε′ = 6.62 at 8 GHz, surpassing conventional composites. Reflection loss of −20.07 dB at 12.4 GHz, high EM wave attenuation. EPSB150@1% rGO boost dielectric and microwave absorption.

A sensing material-free and simple readout MEMS sensor for detecting helium

Abstract In this work, we report a method that enables a standard electrostatic MEMS device to perform complex sensing functionalities, such as detecting the presence of helium without a sensing material or a conditioning circuit. Helium is a noble, odorless, non-reactive gas that is very challenging to detect. It is used in critical applications such as storing nuclear fuel waste inside a dry cask. In these applications, its leakage from the dry cask may indicate the cask's safe operation's degradation. A departure from the common practice of exciting the MEMS around its mechanical resonance, the method is based on exciting the MEMS around its electrical resonance circuit. This method shows that the tiny difference between the air dielectric constant (1.00059) and helium (1.000067) corresponding to only a few Femtofarad level capacitances produces a 25 mV difference without a conditioning circuit. Simulation results confirmed those findings and explored the sensor response at different operation conditions. This method eliminates the need for a heated microstructure and the need for absorption material. This method is not limited to gas sensing. It can be applied to other sensing mechanisms, such as acceleration and pressure measurements, and eliminate the complex circuit to read small capacitance in these applications.

All-Organic Aramid Films with High Temperature Resistance and Electrical Insulation by Introducing Interfacial Hydrogen Bonds.

Although aramid nanofibers (ANFs) consist of rigid poly(terephthalic acid terephthalamide) molecular chains with good high temperature resistance for aerospace and other high-temperature applications, it has poor electrical insulation properties due to internal defects. Currently, the main method to improve the electrical insulation properties is to introduce wide band gap two-dimensional (2D) fillers, such as Boron Nitride Nanosheets (BNNS) or mica flakes, but this inevitably affects the mechanical properties and optical transparency. Cellulose acetate (CA) is originated from acetylation of natural cellulose, and the higher number of hydrogen bond donors on the molecular chain enables it to interbond with many polymers. In this study, CA was introduced into ANFs films, and the all-organic aramid films were prepared by blade coating method. A high dielectric constant of 14.4 as well as a low dielectric loss (0.062 @103 Hz) were obtained, and the dielectric loss of all films was lower than that of the ANFs films, which is attributed to the introduction of interfacial hydrogen bonds that suppressed the loss. In addition, the introduction of interfacial hydrogen bonds introduced deep traps inside the all-organic aramid films, which further improved in breakdown strength from 216.11 MV/m for ANFs film to 367.8 MV/m for the 5 CA film. The prepared all-organic aramid films also showed excellent flexibility as well as high temperature resistance, and the electrical insulation performance under different extreme environments was still higher than that of the ANFs films. This study provides a method for the preparation of high temperature resistant and electrically insulating films, which have great potential applications in fields relating to high temperature circumstance.

Analysis of Enhanced Optical and Electronic Properties of Bismuthene with Pd, Pt Adsorption for Advanced Optoelectronics

This study examines the nanostructures formed after the adsorption of palladium (Pd) and platinum (Pt) metals over bismuthene monolayer. It is emphasized that the adsorption of Pd and Pt significantly influences the optical absorption characteristics of bismuthene. The computational simulations based on density functional theory investigate how adding Pd and Pt metals to bismuthene changes its electronic and optical properties. Pure bismuthene displays substantial optical absorption, primarily in the visible region. When Pd and Pt atoms adsorb over the surface of bismuthene, the absorption coefficient value in the visible and near‐infrared region is enhanced with redshift. Adsorption of Pd and Pt also leads to significant changes in the dielectric constant and refractive index of bismuthene, with distinct peaks observed in the dielectric constant at lower energy after adsorption. Nanostructures composed of Pd/bismuthene and Pt/bismuthene have the potential to predict stable configurations, which makes them appropriate for the absorption of light in the visible and near‐infrared regions. Because of the stable and improved optical absorption accomplished in the desired range of the electromagnetic spectrum, these nanostructures can be utilized for a variety of applications, including but not limited to solar cells and photodetectors, as well as photovoltaics and IR sensor applications.

Phenol formaldehyde‐flax fabric (PF‐F) hybrid composites reinforced with cellulose nanofiber (CNF)—mechanical, morphology, electrical conductivity, electronic structure, optoelectronic, and charge transfer properties

AbstractFor developing an eco‐friendly world, a sustainable solution has encouraged to use natural fibers. Among the various options, lignocellulose fiber‐reinforced composites have captured the interest of material experts and engineers. These remarkable materials offer plentiful supply, inherent sustainability, easily degradability, and affordability, making them an attractive choice for a multitude of uses. Herein, we prepared a series of hybrid cellulose nanofiber (CNF)‐reinforced phenolic composites. Flax fabric was coated with CNF followed by phenolic resin coating was made in this work to check the mechanical, morphological behavior, electrical conductivity, electronic structure, opto‐electronic, and charge transfer properties. We found that 0.5 CNF showed better tensile properties, greater AC conductivity, dielectric constant, and dielectric loss compared with other composites. The electronic structure, opto‐electronic, and charge transfer properties of the PF‐resin/nanocellulose polymer nanocomposite have been systematically examined using density functional theory (DFT). The findings indicate that the PF‐resin/cellulose nanocomposite undergoes intramolecular charge transfer (CT) in response to an external electric field. The negative binding energy exhibited between the DFT optimized PF‐resin/cellulose nanocomposite shows the complex is stable and energy‐favorable.Highlights The impact of CNF on the properties PF‐F hybrid composites was investigated. The mechanical performance has been improved by the addition of CNF. The incorporation of CNF improved the fracture toughness of the composites. The fabricated composite has negative binding energy from DFT studies. A promising high‐performance electroactive polymer and structural material.

Remarkably High Dielectric Constant and Capacitance Density by Ni/ZrO2/TiN Using Nanosecond Laser and Surface Plasma Effect

Rapid thermal annealing (RTA) has been widely used in semiconductor device processing. However, the rise time of RTA, limited to the millisecond (ms) range, is unsuitable for advanced nanometer-scale electronic devices. Using sub-energy bandgap (EG) 532 nm ultra-fast 15 nanosecond (ns) pulsed laser annealing, a record-high dielectric constant (high-κ) of 67.8 and a capacitance density of 75 fF/μm2 at −0.2 V were achieved in Ni/ZrO2/TiN capacitors. According to heat source and diffusion equations, the surface temperature of TiN can reach as high as 870 °C at a laser energy density of 16.2 J/cm2, effectively annealing the ZrO2 material. These record-breaking results are enabled by a novel annealing method—the surface plasma effect generated on the TiN metal. This is because the 2.3 eV (532 nm) pulsed laser energy is significantly lower than the 5.0–5.8 eV energy bandgap (EG) of ZrO2, making it unabsorbable by the ZrO2 dielectric. X-ray diffraction analysis reveals that the large κ value and capacitance density are attributed to the enhanced crystallinity of the cubic-phase ZrO2, which is improved through laser annealing. This advancement is critical for monolithic three-dimensional device integration in the backend of advanced integrated circuits.

Low-temperature growth of wafer-scale amorphous boron nitride films with low-dielectric-constant and controllable thicknesses.

Amorphous boron nitride (aBN) films, with extremely low relative dielectric constant (κ) and chemical inertness, are excellent insulation and packaging materials for electronic device interconnection. It is of great significance to prepare the low-κ aBN films with controllable thickness, but there are still some limitations to achieve the goal. In this study, we succeed in growing wafer-scale aBN films with specific thicknesses from 1.2 to 4.0 nm by varying the growth time and temperature. The thickness of the films increases linearly with growth time and the crystallinity of BN films is precisely controlled by the growth temperature. The preferred temperature for aBN films ranges from 200 to 400 °C. Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscope all confirm the amorphous feature. These films are wafer-scale uniformity and have an ultra-flat surface, with excellent thermal stability and corrosion resistance. Particularly, the growth temperature affects the κ value and breakdown voltage of aBN films. The aBN films grown at 200 °C have the lowest κ value of 1.66 at 100 kHz, along with the breakdown field strength of 5.5 MV/cm. We believe that wafer-level aBN films with various thicknesses can bring new opportunities for the development and application of nanoscale electrical devices.

Superior Flame Retardancy, Mechanical and Dielectric Properties of Epoxy Resin Composites Based on Molybdenum Disulfide‐Melamine Trimetaphosphate Crystallite Composites

ABSTRACTTo improve the flame retardancy, mechanical and dielectric properties of epoxy resin (EP), promoting the application in aeronautic industry and other fields, molybdenum disulfide‐melamine trimetaphosphate (MoS2‐MAP) crystallite composites are synthesized. The chemical, crystalline structure and thermal stabilities of MoS2‐MAPs are thoroughly characterized by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscope (SEM), and thermo‐gravimetric analysis (TGA) techniques, respectively. The morphologies of EP/MoS2‐MAP composites are assessed by SEM, thermal stability by TGA, fire retardancy by limiting oxygen index test (LOI), vertical burning standard test (UL‐94), and cone calorimeter tests, mechanical properties by stress strain tests, and dielectric properties by impedance analyzer. Compared with pure EP, the mechanical, dielectrical properties, thermal stabilities and flame retardancy of EP/MoS2‐MAP composites can be significantly improved due to the good dispersibility of MoS2 and MAP in matrix. While, the properties of EP/MoS2‐MAP composites can be further adjusted by controlling the mass raito of MoS2 and MAP in MoS2‐MAP crystallite. EP with 4 wt% of MoS2‐MAP‐50% (P content: 0.30%) shows the lowest dielectric constant and dielectric loss values on the basis of good flame retardancy and mechanical properties. The results show that the MoS2‐MAP crystallite composites can promote the application of EP composites in aeronautical devices, radar detection and other fields.

Effect of fine-tuned growth temperature on structural, morphological, optical, and electrical properties of Cu2O nanoparticles as candidates for supercapacitor applications

Abstract Cuprous oxide (Cu2O) nanoparticles are promising candidates for optoelectronic and energy applications due to their unique p-type semiconducting nature, optical and electrical properties. This work studies the impact of carefully controlled growth temperature on the structural and morphological, and electrical characteristics of Cu2O nanoparticles synthesized via a coprecipitation method under various temperatures (45°, 55°, 65°, and 75°C). The X-ray diffraction (XRD) analysis indicated a high crystallinity for the fabricated Cu2O nanoparticles with an average crystallite size of approximately (~29 nm), The TEM observations indicate an average particle size of approximately (~50 nm) nanometres. SEM results demonstrated a morphological transition from spherical-cubic to cubic as the aging temperature increased. The electrical properties of the prepared nanoparticles were investigated through AC conductivity and dielectric measurements were taken between 300 K and 550 K temperature range and frequencies ranged from 100 Hz to 5 MHz. Cu2O nanoparticles enhance supercapacitor performance by providing high dielectric constant at low frequencies, improving energy storage, and increasing AC conductivity for efficient charge transport. Their temperature-dependent behaviour and ability to minimize energy losses make them ideal for high-frequency and high-temperature applications. Our findings highlight the exceptional dielectric properties of Cu2O nanoparticles and their remarkable sensitivity to subtle changes in growth temperature. This fine-tuning of the growth conditions allows for the optimization of nanoparticle properties, these characteristics make them suitable candidates for supercapacitor energy applications and other emerging optoelectronic devices.

Aerosol Deposited Polycrystalline PbZr0.53Ti0.47O3 Thick Films with a Large Transverse Piezoelectric Coefficient

The aerosol deposition (AD) method utilizes high kinetic-energy submicron powders to impact and form a film on a substrate. It is a highly efficient deposition method, capable of producing films or coatings with a strong interfacial bonding and a dense nano-grain structure without thermal assistance. In this work, PbZr0.53Ti0.47O3 (PZT53/47) films (~1.2 μm thick) were deposited on Pt/Ti/Si(100) substrates via the AD method. After a conventional annealing process (700 °C for 1 h), these PZT53/47 films displayed a dense, crack-free, nano-grained morphology, corresponding to an optimal electrical performance. A large maximum polarization (Pmax = 70 μC/cm2) and a small coercive field (Ec = 104 kV/cm) were achieved under the maximum applicable electric field of 1.6 MV/cm. The PZT53/47 films also exhibited a large small-field dielectric constant of ~984, a high tunability of 72%, and a low leakage current of ~3.1 × 10−5 A/cm2 @ 40 V. Moreover, the transverse piezoelectric coefficient (e31.f) of these AD-processed films was as high as −4.6 C/m2, comparable to those of sputter-deposited PZT53/47 films. These high-quality PZT53/47 thick films have broad applications in piezoelectric micro-electromechanical systems.

Deciphering the structural, morphological, and electrical properties of rare-earth incorporated barium stannate titanate dielectric material

The primary aim of the current research is to explore the impact of yttrium-doping in barium stannate titanate (Ba[Formula: see text]YxTi[Formula: see text]SnzO3) to investigate the variation in its structural and electrical properties. The specimens were synthesized using a solid-state method, wherein the precursors were heated together until they reacted to form the desired compounds. Subsequently, X-ray diffractometric analysis was employed to confirm the crystallographic phases. Archimedes’ method was used to determine the density of the material. An Electron Paramagnetic Resonance (EPR) study was conducted to examine the nature of defect centers and impurity ions within the synthesized ceramics. Furthermore, the impact of yttrium (Y) substitution on the system’s morphology and grain growth was evaluated through SEM micrographs. Selective compositions were found with enhanced dielectric properties of barium titanate ceramic, exhibiting a dielectric constant of 9816 at the transition point. The highest value among all studied samples had a clear indication of DC conductivity. Piezoelectric coefficient (d[Formula: see text]) and P-E hysteresis loops were also investigated for these samples, indicating potential applications in electronic devices for the modified material’s improved ferroelectric properties.

The effect of cobalt doping on the structure and properties of copper oxide thin films: Evolution in surface morphology, p- to n-type carrier transition and enhancement optoelectronic behavior

This paper reports the preparation of CuO and cobalt (Co)-doped CuO (Co:CuO) thin films (TFs) by a convenient spray pyrolysis reactor. Co concentration (conc.) was varied in CuO TFs from 2 to 8[Formula: see text]at.% at the step of 2[Formula: see text]at.%. In the FESEM images of undoped films, aggregations of nanoparticles were found. The surface morphology of CuO turned into porous and spongy nanostructures for 6[Formula: see text]at.% Co-doping. In XRD analysis, CuO film showed a monoclinic crystal structure with ([Formula: see text]11) peak occurrence. The crystallite size of the films was found to be between 5[Formula: see text]nm and 12[Formula: see text]nm. In UV–vis spectroscopy, the optical transmittance of Co:CuO films increased in the visible region and then saturated in the NIR light region. The highest transmittance of about 96% was found for the 6 at.% Co:CuO film. The band gap of Co:CuO increased with Co doping. Urbach energy, refractive index, dielectric constants and dispersion energy parameters were estimated. Electrical resistivity and carrier concentration were found in the order of [Formula: see text]-cm and [Formula: see text] [Formula: see text]cm[Formula: see text], respectively. CuO films showed n-type conductivity for 4, 6 and 8[Formula: see text]at.% Co-doping. The figure of merit increased significantly with Co-doping up to 6[Formula: see text]at.%, indicating the enhancement in optoelectronic behavior.

First-principles investigation of structural, electronic, and optical properties of RVO4 (R = Er, Eu, Tb, Yb) orthovanadates under pressure

Abstract First-principles calculations were performed to systematically study RVO4 orthovanadates with tetragonal zircon- and scheelite-type structures. The study focused on structural parameters, pressure-induced structural phase transformation, electronic band structure, and optical properties under ambient conditions and hydrostatic pressures up to 10 GPa. Energy-volume and enthalpy-pressure curves were used to determine the phase transition pressures of RVO4 compounds. Among the four compounds examined in both phases, YbVO4 was determined to be less compressible than the other compounds. The computed band structures indicated that RVO4 compounds in both phases are semiconductors with a direct bandgap at the Γ→ Γ point. Optical spectra such as dielectric constants, refractive index, reflectivity, absorption coefficient, birefringence, optical conductivity, and energy loss function were computed as functions of incident radiation energy in the energy range of 0–45 eV. The optical anisotropy of RVO4 compounds was observed in both phases. The computed birefringence values for zircon (scheelite) RVO4 indicate that they are uniaxial positive (negative) crystals and have a large birefringence value. Hydrostatic pressure was found to play an important role in the structural, optical, and electronic properties of both phases of RVO4 compounds.