Permittivity Of Material Research Articles

High insulation resistivity and low dielectric loss in (Ta, Al)‐codoped BaTiO3 colossal permittivity materials

AbstractLow insulation resistivity is a key factor limiting the practical application of colossal permittivity (CP) ceramics in electronic components. In this study, BaTiO3–0.01Ta2O5–xAl2O3 (BTAx, x = 0.005, 0.01, 0.015, 0.02) CP ceramics with high insulation resistance were successfully prepared by sintering in N2. In particular, BTA0.015 ceramic exhibits CP (εr = 2.01 × 105, 1 kHz), low dielectric loss (tanδ = 0.044, 1 kHz), high insulation resistivity (ρv = 1.4 × 109 Ω cm, DC voltage (DC) 100 V), and superior frequency and thermal stability (20 Hz–1 MHz, room temperature–350°C). The polarization mechanism, dielectric and insulating properties were investigated by different atmosphere processing, scanning electron microscopy (SEM) X‐ray photoelectron spectroscopy (XPS), and impedance analysis. Moderate doping of Al2O3 facilitates the construction of electron‐pinned defect dipoles, which improves the dielectric properties. In addition, the ceramics feature an extremely fine grain size, which is conducive to suppressing the long‐range migration of delocalized electrons. The combination of electron pinning defect dipole effects and internal barrier layer capacitance effects are the responsible for the giant dielectric constant. This research shows that the defect dipole‐dependent polarization can be employed to design highly insulating BaTiO3‐based CP ceramics.

Quantum integrable systems and concentration of plasmon resonance

We are concerned with the quantitative mathematical understanding of surface plasmon resonance (SPR) when d \geq 3 . SPR is the resonant oscillation of conducting electrons at the interface between negative and positive permittivity materials and forms the basis of many cutting-edge applications of metamaterials. It has recently been found that the SPR concentrates due to a curvature effect. In this paper, we derive sharper and more explicit characterizations of the SPR concentration at high-curvature places in both static and quasi-static regimes. The study boils down to analyzing the geometry of the so-called Neumann–Poincaré (NP) operators, which are certain pseudodifferential operators acting on the interfacial boundary. We propose to study the joint Hamiltonian flow of an integrable system given by the moment map defined by the NP operator. Via considering the Heisenberg picture and lifting the joint flow to a joint wave propagator, we establish a more general version of quantum ergodicity on each leaf of the foliation of this integrable system, which can then be used to establish the desired SPR concentration results. The mathematical framework developed in this paper leverages the Heisenberg picture of quantization and extends some results on quantum integrable systems via generalizing the concept of quantum ergodicity, which can be of independent interest in spectral theory and potential theory.

Deterministic reflection contrast ellipsometry for thick multilayer two-dimensional heterostructures

Abstract Optical spectroscopy is a powerful tool for characterizing the properties of two-dimensional (2D) heterostructures. However, extracting the permittivity information of each 2D layer in optically thick heterostructures is challenging because of interference. To accurately measure the optical permittivity of each 2D layer in a heterostructure or on a substrate with a thick insulating spacer, such as oxides, we propose deterministic reflection contrast ellipsometry (DRCE). Our DRCE method has two advantages over conventional techniques. It deterministically measures the optical permittivity of 2D materials using only the measured reflection spectra of the heterostructure, rather than dispersion fitting as in spectroscopic ellipsometry. Additionally, the DRCE is free of excitonic energy errors in reflection-contrast spectroscopy. We believe that DRCE will enable accurate and rapid characterization of 2D materials.

A Novel Differential Microwave Sensor Based on Reflective-Mode Phase Variation of Stepped-Impedance Transmission Lines for Extracting Permittivity of Dielectric Materials

A Novel Differential Microwave Sensor Based on Reflective-Mode Phase Variation of Stepped-Impedance Transmission Lines for Extracting Permittivity of Dielectric Materials

Fabrication of Cellulose Powder Dielectric Composite Material using Pineapple Leaves Fiber

Pineapple, known for its delicious taste and nutritional value, generates substantial waste in the form of cores, leaves, and skin, resulting in significant yearly accumulations. Efficient disposal of pineapple waste has become a critical challenge due to its increasing production and potential environmental pollution. The objective of this paper is to volarize natural fibre derived from pineapple waste by fabricating it into a new dielectric composite material. The fabrication process of dielectric composite material was achieved by using the optimization technique through Design Expert software, resulting in noteworthy findings. Then, the properties of the fabricated materials were analysed in terms of their permittivity value and elemental composition. The permittivity value of the newly fabricated dielectric materials was measured using the vector network analyser (VNA) method, while their elemental composition was characterized using energy-dispersive X-ray (EDX) spectroscopy. The correlation between elemental composition and the permittivity value of newly fabricated composite materials is analysed in this paper. As a result, the dielectric composite material attained its highest permittivity (4.08) when composed of 76.02% carbon and 22.61% oxygen. Conversely, the material exhibited a lower permittivity value (2.87) when its carbon content decreased to 69.32% and its oxygen content increased to 29.81%. This outcome highlights the crucial role of carbon in absorbing and storing electromagnetic signals, influencing the dielectric properties of the material. In conclusion, this paper unveils a ground-breaking use for waste pineapple leaves, showcasing how their carbon content significantly affects the resulting dielectric composite material's permittivity. This innovative eco-friendly material presents a sustainable alternative for non-recyclable dielectric materials in electronic devices such as PCBs, antennas, and sensors, for example.

Study of permeability and permittivity of [formula omitted]-Fe[formula omitted]O[formula omitted] using computer simulation method

This study proposes a computational method to directly obtain the frequency-dependent permeability and permittivity of materials from computer simulation data. The method combines first-principles calculations, Green’s function formalism, and magnetic moment dynamics simulations. Using α-Fe2O3 as an example, we demonstrate the validation process of the computational approach. By calculating the time correlation functions of electric and magnetic dipole moments and applying linear response theory, we successfully obtained the frequency-dependent permeability and permittivity of α-Fe2O3 at 300 K. The calculated results agree well with experimental values, proving the efficacy of the proposed computational method. This study provides a reliable computational pathway to predict electromagnetic parameters of materials using computer simulations.

Characterizing Complex Permittivity of Thin Materials by Free Space Transmission and Reflection Coefficients

Characterizing Complex Permittivity of Thin Materials by Free Space Transmission and Reflection Coefficients

АВТОМАТИЗИРОВАННЫЕ ИССЛЕДОВАНИЯ ДИЭЛЕКТРИЧЕСКИХ ПАРАМЕТРОВ ПОЛИМЕРНЫХ МАТЕРИАЛОВ В СОСТАВЕ ТЕХНОЛОГИЧЕСКОЙ СМЕСИ

The use of high-quality polymer film as packaging makes it possible to maintain marketable quality and reduce losses during storage of agricultural products even without additional processing. An overview of the existing control systems for the electrophysical parameters of polymeric materials is presented, the use of which serves as the basis for selecting the correct processing modes with the use of high-frequency electrothermal processing. When measuring the electrophysical characteristics of polymeric materials in multicomponent mixtures using standard testing methods, significant errors occur. In this regard, it is necessary to improve laboratory methods and diagnostic tools to solve research problems by automating the process of accounting for air gaps and studying their influence on the process of controlling the electrophysical parameters of the technological mixture. (Research purpose) The research purpose is developing an automated control system for the installation to determine the electrophysical parameters of multicomponent polymeric materials and studying the effect on the dielectric loss and dielectric permittivity of existing air gaps. (Materials and methods) Considered a number of methods to establish the methodology for conducting experimental studies on finding the electrophysical parameters of technological systems with air. (Results and discussion) We have developed an automated installation for determining the parameters of materials, created on the basis of domestic equipment of the VM-560 model. Methods of hardware and algorithmic implementation of the developed system of automated control of the process of investigation and control of the dielectric losses and permittivity of granular polymeric materials were presented. Experimental studies of the effect of air gaps and insulating material on the electrophysical properties of polymeric materials were performed. Refined electrophysical parameters of multicomponent polymers used in the production of films for packaging materials resistant to ultraviolet radiation have been obtained. (Conclusions) It was shown that the developed control system allowed to increase the accuracy of measurement by 12 percent.

High green index electromagnetic interference shields with semiconducting Bi2S3 fillers in a PEDOT:PSS matrix.

Conventional metallic electromagnetic interference (EMI) shields, as well as the emerging 2D material-based shields, meet the shielding effectiveness (SE) needs of most applications. However, their shielding performance is dominated by the reflection of incoming radiation due to their high electrical conductivity, which leads to secondary pollution. This problem is getting exacerbated with the proliferation of electronics and communication networks in modern society. Thus, EMI shields that function dominantly by the absorption of incoming radiation are highly desirable. Such shields would be characterized by a green index, which is the ratio of absorbance over reflectance, close to or greater than one. For nonmagnetic materials, the best way to reduce the undesirable large impedance mismatch is to reduce the effective permittivity of the shield material. Here, we present a new EMI shield with a semiconductor Bi2S3 filler in a conducting PEDOT:PSS polymer matrix, instead of the conventional conductive fillers, to reduce the effective permittivity and demonstrate that even a light loading of only 10% Bi2S3 provides high SE of over 40 dB with a green index value of 0.75. Increasing the filler content to 15 wt% increases the green index close to unity while dropping the SE to 30 dB. The shielding mechanism is explained through electromagnetic parameter measurements and supplemented by density functional theory calculations. This work lays the foundation for the advancement of lightweight and ultrathin green EMI shields with minimum secondary pollution.

Enhanced plasma jet generation through numerical integration and dielectric influence analysis

This paper reports a study on the production of plasma jets that are out of equilibrium through numerical solutions of electron energy distribution function using a self-consistent methodology. The approach includes the integration of the continuity, momentum, and Poisson equations, which allows the use of the mean electron energy to fit the transport and source coefficients. The paper concurrently presents an analysis of cold plasma generation in a tube. This investigation utilizes COMSOL Multiphysics software to simulate the electric field, potential, and electron density in space. Moreover, the study examines how the dielectric’s permittivity impacts plasma propagation. The simulated outcomes are compared with experimental and numerical results. As electron density, ionization rate and electric potential vary during plasma propagation on a dielectric surface, and the permittivity of dielectric materials increases, it promotes an increase in electron density around it. This, in turn, accelerates the ionization front, indicating efficient polarization and accumulation of electric charges, specifically electrons, near the dielectric surface.

A Reduction Method of Phantom Shell Effects for APD Extraction Using Negative Permittivity Material

A Reduction Method of Phantom Shell Effects for APD Extraction Using Negative Permittivity Material

Surface modification of carbon fibers for enhanced electromagnetic absorption

The exceptional chemical and physical properties of carbon fiber make it highly promising for utilization in the field of wave-absorbing materials. However, the low magnetic loss and high complex permittivity of conventional carbon fiber materials limit their use in wave-absorbing materials. Hence, this study presents the synthesis of a FeCoNi/N-doped carbon coating/SCF composite with a distinctive microstructure by an in-situ reduction process. The successful formation of this unique architecture was confirmed through various characterization techniques. The composite material displayed both magnetic and dielectric characteristics. It showed an effective bandwidth spanning 14.77 GHz with a reflection loss (RL) of − 10 dB or less. In addition, it attained the minimum RL value of − 50.5 dB at a distance of 3.5 mm. The composite material is hypothesized to show great potential in electromagnetic wave absorption.

Experimental and theoretical investigations on the lattice defects and sintering atmosphere tuning the colossal permittivity of SrTiO3 ceramics

The Sr0.995La0.005TiO3 ceramics were fabricated with traditional solid-state methods under diverse sintering atmospheres. The dielectric properties have a significant correlation with the sintering atmosphere, while showing favorable temperature and frequency stability. As sintered in a mixed hydrogen-nitrogen atmosphere, Sr0.995La0.005TiO3 ceramics exhibited a colossal permittivity (ԑr ∼ 31307), low dielectric loss (tanδ ∼ 0.038) and good frequency stability synergistic temperature stability (−70 °C-180 °C, ΔC/C25°C ≤ ±15 %). The association mechanism of oxygen vacancies, lattice defects, and dielectric characteristics is evaluated in the context of experiments and first-principles. The phase structure and microstructure analysis revealed that the ceramics contained a two-phase structure with a SrTiO3 phase and a TiO2 second phase. The analysis of elemental valence and dielectric characterization demonstrated that defective dipoles, oxygen vacancies, and defect clusters resulting from non-homogeneous ion substitution are the major reasons for contributing to the colossal permittivity and low dielectric loss of the ceramics. This revealed that the electron-pinned defect dipole (EPDD) effect dominates in Sr0.995La0.005TiO3 ceramics. In addition, it can be established that the SrTiO3 phase and TiO2 phase contribute to the EPDD effect simultaneously, with SrTiO3 main phase taking the main role. According to the ELF plot analysis, when the content of oxygen vacancies is high, electrons accumulate at oxygen vacancies and defect clusters, leading to a high localization of electrons, which contributes to colossal permittivity and low dielectric loss of ceramics. The results are promising in colossal permittivity (CP) materials.

Understanding the negative permittivity behavior of polyvinyl alcohol based metamaterials under radio frequency

Functional metamaterials that exhibit negative dielectric permittivity through percolative network formation have attracted immense attention due to their significant potential for a wide range of applications in electronic devices. Negative permittivity has taken off as a research topic recent years in percolative composites. The polymer nanocomposites (PVA/H-Pa-G) were prepared using the α-Fe2O3 modified GNP and HCl doped polyaniline (Pani) based nanofillers (H-Pa-G). The as prepared samples were characterized in order to analyze their dielectric response for understanding the negative permittivity behavior. Below the percolation threshold for the polymer nanocomposite with 0.10%, 0.25% H-Pa-G nanofiller weight fraction, an increase in σac conductivity is observed with increase in frequency. The dielectric study confirmed the negative permittivity behavior for the polymer nanocomposite (0.50%, 1.00% and 2.00%) above the percolation threshold. This can be mainly attributed to the presence of the conductive network of H-Pa-G nanofiller in the PVA matrix. On the contrary, the positive permittivity is due to the insulative nature of PVA matrix. The empirical data of real permittivity was fitted using the Drude model that corresponded well with the experimental data with the fp = 1.31 GHz which is further certified by the equivalent circuit model fitting. This proposed work strongly suggest the implication of the as prepared polymer nanocomposite for the negative permittivity materials based applications.

Material characterization by using T- stub based microstrip patch sensor

In this article, a dual port T-stub based planar sensor is designed with defective ground structure to analyze the properties of lossless dielectric material. The observation is done on the basis of reflection response i.e., S11 and also by analyzing imaginary part (reactive part) of z-parameters (Z11, Z21). This proposed sensor is applicable to sense the relative permittivity in the given range i.e., ϵr =1-12. In this study, the capacitive response of the sensor is analyzed with varying relative permittivity of material under test (MUT). It is found that with increase in the relative permittivity of MUT, the capacitance of the sensor increases and therefore significant shift in frequency is observed.

Cylindrical cavity resonator for complex permittivity estimation at 1.2853 GHz: Coir and skins of rice, banana, lemon, watermelon, pineapple and papaya

The knowledge of dielectric properties of organic materials at microwave frequencies is important for different applications in agriculture, food, or other similar research areas. The method of the low-cost disturbed cylindrical cavity resonator is a common measurement technique that considers resonant frequency shift when inserting samples of materials inside the cavity. Frequency shifts together with the knowledge of the complex permittivity of a reference material allow the estimation of the permittivity of a material under test. In this paper, the complex permittivity, and the loss tangent of dried and powdered agricultural wastes from the state of Colima in Mexico are obtained at 1.2853. The materials under test are coir and skins of rice, banana, lemon, watermelon, pineapple, and papaya since they are one of the most abundant agricultural wastes in the state of Colima in Mexico.

A mathematical model and microcontroller-based method for measuring dielectric permittivity and discharge characteristics with Arduino ATmega 328: a case study in a physics laboratory

A microcontroller-based measuring instrument and a new mathematical model are used to investigate capacitor permittivity and dielectric materials' charge-discharge characteristics. In this study, a prototype capacitive permittivity measurement apparatus for dielectric materials was carefully developed using an Arduino microcontroller, a resistor, and a capacitor. The experimental setup comprises a capacitor-resistor circuit, wherein a 5-volt power supply sourced from the microcontroller interfaces with a computer. During the charging process, a comprehensive evaluation of model-data alignment was performed, yielding values of 0.54252156, 0.9951, and 111.2508701 for the sum of squares error (SSE), the coefficient of determination (R-squared), and the sum of squares total (SST), respectively. Similarly, the analysis extended to the discharging process, unveiling values of 5.10174756, 0.962805684, and 137.1647082 for SSE, R-squared, and SST, respectively. These findings confirm the accuracy of the microcontroller that was programmed by incorporating a model in precisely measuring the relative permittivity of dielectric materials and capacitance values, with an R-squared value above 0.95 following capacitor literature benchmarks. The novelty of this study is that this configuration enabled the precise assessment of both permittivity and the charge-discharge characteristics of the dielectric materials within the capacitor. This methodology made it possible to accurately measure the permittivity and charge-discharge characteristics of dielectric materials within a capacitor. The scientific significance of this research lies in its ability to provide a carefully developed instrument capable of investigating the permittivity of dielectric materials and capacitor capacitance measurements. Scholars, international engineering communities, and academics can use this technological breakthrough to advance research into dielectric material properties and capacitor characteristics.

Co-utilization of electric arc furnace dust and copper slag for preparing zinc ferrite based on microwave roasting

The feasibility of preparing zinc ferrite from high-zinc electric arc furnace (EAF) dust and high-iron copper slag (CS) based on direct microwave roasting of the wastes together was assessed in this study, with a focus on the effect of microwave roasting temperature. According to the permittivity and permeability measurements of the raw materials, in conjunction with thermodynamic and experimental analyses, it was found that increasing temperature facilitated the formation of zinc ferrite. By fixing the Fe/Zn molar ratio of 2.0 and roasting time of 30 min, elevating the temperature from 500 ºC to 700 ºC led to a significant increase of the percentage of acid-insoluble zinc in the form of zinc ferrite from 81.48% to 94.93%. Further increase of the temperature to 900 °C could not evidently promote the formation of zinc ferrite. After removing impurities by dilute HCl solution and nano milling, the zinc ferrite product had a single phase with the purity of 99.9 wt%. It can act as a great adsorbent of heavy metal ions due to its superior adsorption capacities of 87.99 mg/g, 86.51 mg/g, 86.22 mg/g, and 90.32 mg/g for Pb(II), Cr(VI), Cd(II), and Hg(II), respectively, and as a catalyst for removing tetracycline (TC) using peroxymonosulfate (PMS) with the removal efficiency of 78.54% after 40 min under visible light irradiation. This study offers a facile method for co-utilization of EAF dust and CS to produce value-added functional materials.

High-Temperature Measurement Technology for Microwave Surface Resistance of Metal Materials

The resonant cavity method is a commonly used method for high-temperature testing of the complex permittivity of dielectric materials. When a resonant cavity is used for high-temperature testing, the microwave surface resistance of the cavity metal material will deteriorate due to factors such as oxidation reaction and thermal fatigue, resulting in a decrease in testing accuracy and repeatability. Therefore, when designing a high-temperature resonant cavity, the temperature response characteristics of the microwave surface resistance of the cavity metal material should be obtained in advance. In this paper, a high-temperature measurement method of microwave surface resistance of metal materials based on a separate cylindrical resonator is proposed, a mathematical model of microwave surface resistance inversion based on the resonator quality factor is established, and a high-temperature measurement system of microwave surface resistance is integrated. The reliability of the proposed method and system is verified through simulation and experiment. The measurement frequency covers 7-18 GHz, and the maximum test temperature reaches 500°C. Systematic error of microwave surface resistance measurement at room temperature is less than 3%.

X9R-type SrTiO3 based ceramics with colossal dielectric permittivity and low loss derived from defect engineering and high-energy ball milling

The miniaturization of electronic components has become a megatrend in the future, making colossal dielectric permittivity materials receive unprecedented attention. In this work, we proposed a universal route to achieve colossal dielectric permittivity, low loss factor and excellent dielectric temperature stability in rare earth doped perovskite oxide SrTiO3. Sm doped SrTiO3 ceramics prepared by high-energy ball milling exhibit ultrahigh dielectric permittivity 441,543, low loss factor 0.02, good dielectric temperature stability (<15 %) in the temperature range of −55–200 °C, and very high resistance 109Ω, which meets the EIA X9R standard, XPS and impedance spectra indicate that the electron-pinned defect-dipoles effect is the origin of colossal dielectric permittivity and low loss factor. This work shows that Sm-doped SrTiO3 activated by high-energy ball milling has broad prospects in the applications of thermally-stable miniaturized capacitors.