Dissipation Factor Research Articles

Detection of plant cadmium toxicity by monitoring dielectric response of intact root systems on a fine timescale.

The root dielectric response was measured on a minute scale to assess its efficiency for monitoring short-term cadmium (Cd) toxicity non-destructively. Electrical capacitance (CR), dissipation factor (DR) and electrical conductance (GR) were detected during the 24 to 168 h after Cd treatment (0, 20, 50 mg Cd2+ kg-1 substrate) in potted maize, cucumber and pea. Stress was also evaluated by measuring leaf chlorophyll content, Fv/Fm and stomatal conductance (gs) in situ, and shoot and root mass and total root length after harvest. CR showed a clear diurnal pattern, reflecting the water uptake rate, and decreased significantly in response to excessive Cd due to impeded root growth, the reduced tissue permittivity caused by accelerated lignification, and root ageing. Cd exposure markedly increased DR, indicating greater conductive energy loss due to oxidative membrane damage and enhanced electrolyte leakage. GR, which was coupled with root hydraulic conductance and varied diurnally, was increased transiently by Cd toxicity due to enhanced membrane permeability, but declined thereafter owing to stress-induced leaf senescence and transpiration loss. The time series of impedance components indicated the comparatively high Cd tolerance of the applied maize and the sensitivity of pea cultivar, which was confirmed by visible shoot symptoms, repeated physiological investigations and biomass measurements. The results demonstrated the potential of single-frequency dielectric measurements to follow certain aspects of the stress response of different species on a fine timescale without plant injury. The approach can be combined with widely used plant physiological methods and could contribute to breeding crop genotypes with improved stress tolerance.

Mesomorphism and Tribotechnical Characteristics of Lubricant Compositions with Mesogenic Additives Carboxylates Cu(II)

The purpose of the work is to characterize the lubricants based on Llitol-24 and synthetic solidol with additives copper(II) carboxylates when using them in friction nodes in loading conditions and temperature. The lubricant compositions with additives copper(II) carboxylates based on synthetic solidol and Litol-24 form the columnar mesophases depending on thermodynamical conditions and concentration of additives.Methods. We study the lubricant compositions with dielectric spectroscopy and и polarization light microscopy. The studies lubricant compositions are tested on the frictional machines by preceding authors, which performed their synthesis and numerical estimations for their geometry parameters. It is shown, that the columnar mesophase formed by the compositions with copper(II) carboxylates simulates favourable tribological conditions for lubrication (reduction of the friction coefficient at the appointed range of additive concentrations and reduction of wear) and unlike to crystalline phases, shows orientation effects at the surface of interacting surfaces of machine elements and devices. These factsmotivate the study of influence of physicochemical properties and composition on mesomorphism of considered lubricant compositions.Results. In our measurements, we found the main dielectric characteristics of two kinds of the lubricant compositions: dielectric constant and dielectric loss, electroconductivity, dissipation factor, the Arrhenius functions are plotted, and the activation energies of the lubricant compositions we study are calculated. The microphotogram for textures of the lubricant compositions depending on temperature and concentrations are received. The differences in mesomorphic properties of the lubricant compositions with additives Cu(II) valerate and isovalerate are confirmed.The conclusion of the work is that the composition of the lubricant is optimized by the choice of additive concentration, the length of the mesogenic chain of the copper(II) carboxylate molecule and its conformation.

Unraveling the dielectric and electrical properties of binary BaTiO3/Ba0.98Ca0.01Mg0.01Fe12O19 composites

In this study, composite materials of barium titanate (BaTiO3 or BTO) phase embedded with different contents of Ba0.96Ca0.02Mg0.02Fe12O19 (BCMFO) hexaferrite phase as (BTO)1-x/(BCMFO)x (x = 0.00, 0.02, 0.05, 0.10, and 1.00) composites were prepared. The successful formation of the desired samples was established via X-ray diffraction. Additional peaks showing a chemical reaction between the two phases as a result of the heat treatment were not found. The co-existence of the two-component phases was further confirmed via field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, wherein rounded spherical grains (with nanometric size <200 nm) correspond to the BTO phase while plates-like shaped grains with larger size (with micrometric size) correspond to the BCMFO hexaferrite phase. This study also investigates the impact of the composition ratio of BCMFO to BTO composites on electrical and dielectric properties through comprehensive parameter-based analyses using impedance spectroscopy. Parameters explored include conductivity, dielectric constant, dielectric loss, dissipation factor, and complex modulus, alongside Nyquist analysis of Cole-Cole modulus functions. The activation energies range from approximately 40 to 431 meV. The study suggests the involvement of electron-hole hopping, polaronic, and ionic mechanisms in conduction within intra-grains and grain boundaries. Results reveal strong dependencies of all dielectric parameters on both frequency and composition ratio. Nyquist plots demonstrate distinct semicircles reflecting contributions from intra-grain, grain boundary, and BCMFO components. The extent of dielectric loss is found to be influenced by factors such as porosity, density, homogeneity, and grain size, influenced by sintering and composition conditions. The presence of these semicircles in Nyquist plots indicates different relaxation phenomena associated with charge carrier mobility within the grain boundary and the grain itself. Additionally, the diameter of these semicircles correlates with the resistance values of both grain boundary and grain. These findings suggest the potential for tuning dielectric parameters by adjusting composition ratios, particularly relevant for applications in micro-device technologies such as multilayer chip capacitors and multilayer chip inductors, facing new challenges.

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4'-butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles.

The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4'-butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The 'universal' exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the 'critical-like' evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, 'critical-like' behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.

Design, Fabrication and Performance Analysis of a Portable, Antenna Analyzer Based, Quartz Crystal Microbalance Measuring System with Energy Dissipation

Impedance measurements play a critical role in analyzing the electrical behavior of piezoelectric biosensors in general. Antenna analyzers are engineered to measure the specific case of input impedance for antenna systems. In this study small form factor antenna analyzer is repurposed to work as driving circuit for a Quartz Crystal Microbalance (QCM) biosensor in combination with a single board computer as an indication of how small and portable an impedance measuring system can be made, while allowing monitoring of important parameters of series and parallel resonance frequencies together with dissipation factor. A QCM crystal with a 10 MHz fundamental resonance frequency is employed to determine the limit of detection of the system in Bovine Serum Albumin (BSA) and glycerol solutions. Dissipation factor and phase angle were monitored during the experiments. Limit of detection is 20 µg/ml BSA in phosphate buffer saline (PBS) and 250 µl of glycerol in 100 ml of deionized water.

A novel approach towards parametric assessment of reliability and resilience of high voltage mica‐based insulation systems by statistical analysis of experimental failure data

AbstractInsulation systems in high‐voltage electric machines play a pivotal role in the reliable operation and longevity of the equipment. Mica‐based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation degradation. Numerous qualifications tests, such as voltage endurance, are outlined in IEC and IEEE standards. The authors, however, take a different parametric approach, opting for reliability assessment of insulation systems using derived three‐parameter Weibull models. Therefore, instead of simple pass–fail criteria, empirical data is employed to determine failure rate probabilities quantitatively and objectively. Experimental data, including breakdown, dissipation factor, and partial discharge measurements, are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard functions. The rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica content. Variation of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un, hence identifying opportunities for design improvement and uncovering performance boundaries. Ultimately, the developed framework enhances comprehension of insulation system failure probabilities, guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

Measurement uncertainty in on-line bushing monitoring

The high voltage bushing on-line monitoring has been performed for many years to prevent unexpected rapid power network failures. Network unbalance correction, based on separate voltage phase measurement or phasor technique, effectively improves the measurements of bushing dielectric dissipation factor tgδ and capacitance factor C1. The newly implemented monitoring units reveal that the uncertainty of station voltage measuring transformers manifest the greatest influence on the overall uncertainty budget, regardless of the measurement method.

Up-gradation of the dielectric, physical & chemical properties of cottonseed-based, non-edible green nanofluids as sustainable alternatives for high-voltage equipment's insulation fluids

The use of natural ester oils as electrically insulating fluids has gained significant attention from industries and electrical utilities as they aim to replace traditional mineral oils. However, most natural ester oils are derived from edible products, which has the potential to contribute to the food crisis. Therefore, nonedible green nanofluids made from cottonseed oil (CSO) have been targeted as a keen solution to this issue. However, Al2O3, TiO2, Fe2O3, SiO2, and graphene nanoparticles at (0.025, 0.05, and 0.075 wt/vol%) were used as additives, along with surfactant Olic Ac-id and Ethanol (1:5) due to their promising impact on the dielectric and thermal properties of the nanofluid. The nanofluid synthesis process was practically conducted in HV & Chemical Laboratories using one-step and two-step methods, and their breakdown voltage results and chemical properties (e.g., fire point, flash point, cloud point, pour point, viscosity, acidity, moisture content, resistivity, and dissipation factor) were compared. The physical mechanisms underlying these properties were also analyzed and tested. For the validation of the proposed vegetable oil the results have been compared with traditional mineral oil for high-voltage equipment's. The findings suggest that the proposed nonedible green nanofluids-based cottonseed oil (CSO) has a high potential to be used as electrically insulating fluids, providing a sustainable alternative to conventional mineral oils. Overall, this study provides insights into the use of non-edible green nanofluids as a solution to the potential contribution of natural ester oils to the food crisis. The findings highlight the importance of sustainable solutions in the energy industry and the need for further research in this area.

A comprehensive study of dielectric, modulus, impedance, and conductivity of SrCeO3 synthesized by the combustion method

AbstractIn this work, perovskite oxide SrCeO3 was synthesized using the solution combustion method (SCM). Synthesized samples have been characterized using X‐ray diffraction (XRD), Raman, ultra violet (UV)–visible spectroscopy, and scanning electron microscopy (SEM) techniques. The XRD and Rietveld refinement has confirmed the orthorhombic structure with space group Pnma. The average grain size of this ceramic sample is 1.2 µm. The dielectric constant, dissipation factor, modulus, impedance, and alternating current (AC) and direct current (DC) conductivities were analyzed in the temperature range RT to 600°C and frequency range 20 Hz–2 MHz. Further, it was observed that the role of grain boundaries in dielectric and electrical properties is significant, at low temperatures. The origin of the dielectric relaxation and conduction process is the same. The activation energy for DC conduction (Edc) was found to be .79 eV. Electrical conduction/relaxation is assigned to the diffusion of doubly ionized oxygen (Vo··). The value of DC conductivity (1.2 × 10−3 Ω−1 cm−1 at 600°C) and activation energy of .79 eV is very close to the values reported for doped CeO2‐based oxide ion conductors for SOFCs. This study has demonstrated that SrCeO3 can be an alternative candidate for the oxide ion conductor electrolyte application and the potential to be used as a thermally stable capacitor application for microwave dielectric applications.

Chiral magnetic waves in strongly coupled Weyl semimetals

Propagating chiral magnetic waves (CMW) are expected to exist in chiral plasmas due to the interplay between the chiral magnetic and chiral separation effects induced by the presence of a chiral anomaly. Unfortunately, it was pointed out that, because of the effects of electric conductivity and dissipation, CMW are overdamped and therefore their signatures are unlikely to be seen in heavy-ion collision experiments and in the quark gluon plasma. Nonetheless, the chiral anomaly plays a fundamental role in Weyl semimetals and their anomalous transport properties as well. Hence, CMW could be potentially observed in topological semimetals using table-top experiments. By using a holographic model for strongly coupled Weyl semimetals, we investigate in detail the nature of CMW in presence of Coulomb interactions and axial charge relaxation and estimate whether, and in which regimes, CMW could be observed as underdamped collective excitations in topological materials.

Structural and Dielectric Properties of Titania Co-Doped with Yttrium and Niobium: Experimental Evidence and DFT Study

This work explores the impact of the sintering temperature and co-dopant contents on the microstructure and dielectric properties of (Y0.5Nb0.5)xTi1−xO2 (0.025 ≤ x ≤ 0.10) ceramics synthesized by the solid state reaction method. The physical mechanism underlying the colossal electric permittivity was systematically investigated with experimental methods and first principles calculations. All specimens exhibited the characteristic tetragonal structure of rutile, besides secondary phases. A niobium- and yttrium-rich secondary phase emerged at the grain boundaries after heating at 1500 °C, changing the main sintering mechanism. The highest value of the electric permittivity (13499 @ 60 °C and 10 kHz) was obtained for (Y0.5Nb0.5)0.05Ti0.95O2 sintered at 1480 °C, and the lowest dissipation factor (0.21@ 60 °C and 10 kHz) for (Y0.5Nb0.5)0.1Ti0.90O2 sintered at 1500 °C. The dielectric properties of Y3+ and Nb5+ co-doped TiO2 are attributed to the internal barrier layer capacitance (IBLC) and electron-pinned dipole defect (EPDD) mechanisms.

Crystal structure and peculiarities of microwave parameters of Mg1-xZnxFe2O4 nanospinel ferrites

Employing an advanced citrate precursor methodology, we successfully synthesized nanoscale spinel ferrites, denoted as Mg1-xZnxFe2O4 (where x ranges between 0.0 and 1.0) or MZFO. Comprehensive analysis, utilizing state-of-the-art X-ray diffraction (XRD) techniques, demonstrated the defining attributes of the crystal structure. All examined specimens consistently exhibited a singular phase, adopting a cubic crystalline architecture. XRD pattern analysis allowed us to deduce the average particle dimensions of these ferrite specimens, which span between 17.2 nm and 31.5 nm. This observed size distribution corroborates well with transmission electron microscopy (TEM) imagery estimations. Delving into the Fourier-transform infrared (FTIR) spectra, two distinctive absorption bands of ferrites emerged: the first between 540 and 570 cm−1 and the subsequent between 339 and 435 cm−1. To glean insight into the electromagnetic attributes of MZFO, we meticulously assessed the experimentally ascertained S-parameters. This scrutiny spanned a frequency spectrum of 8–18 GHz. It was inferred that electromagnetic wave energy dissipation arises chiefly from a combination of electrical and magnetic phenomena. The underlying mechanisms of electrical dissipation can be attributed to polarization processes. Concurrently, the magnetic energy losses predominantly stem from magnetization reversal dynamics. Notably, a substantial attenuation observed in the reflected wave energy, ranging between −10 and −18.5 dB, augments the potential for this material's integration into practical applications.

Zinc Oxide Filler Effect on Dissipation Factor of High-Density Polyethylene

Polymer Nano-composites (PNC) are efficient materials that consist of polymer matrix and nanoparticles to create a new generation with excellent properties. In this paper a PNC filler-based Zinc oxide (ZnO) is used for enhancing the dissipation factor (DF) or Tan δ of the obtained polymer compared to the individual polymer material and improving the electrical properties of high-density polyethylene (HDPE). The electrical properties of HDPE are investigated under different concentrations of zinc oxide including (0, 10, 20, 30, and 40 wt.%) as well as under different conditions including the variations of temperature (25-150 Celsius) and frequencies (0.1 kHz to 1 MHz). The simulation results reveal that inclusion Zinc oxide as filler can improve the electrical properties of HDPE. In addition to that the minimum value of dissipation factor and the best electrical properties can be obtained at concentration 10 % loading compared to the other concentration levels. Curve fitting solutions were performed to determine the best fit for the experimental results. African Vultures Optimization Algorithm (AVOA) was used to determine the optimal value of zinc oxide filler percentage to obtain the best optimal value of dissipation factor.

Assessment of voltage harmonics' impact on the maximum load capacity of the power supply transformer for the LHCD system.

To study the influence of the voltage total harmonic distortion (THDV) and its spectrum on the harmonic loss factor (FHL) and the maximum allowable load capacity ratio (Imax (pu)) for the transformer of the LHCD system, we use MATLAB software to model the LHCD system and study the winding loss and maximum allowed load capacity of the LHCD system transformer when the supply voltage source is sinusoidal and non-sinusoidal, respectively. The calculation is carried out by the method of IEEE standard C57.110 and the method of considering the skin effect. The calculation results of both methods clearly show that the THDV value of the supply voltage has a significant effect on the harmonic dissipation factor (FHL) and the maximum allowable load capacity ratio (Imax (pu)) of the transformer. And the calculation method considering the skin effect increases the maximum allowable load capacity ratio of the LHCD system transformer by about 2%. The research results have important reference value for the future retrofit design of LHCD system transformers.

Huge permittivity with decreasing dissipation factor and humidity sensing properties of CaCu2.9Mg0.1Ti4.2-xGexO12 ceramics

CaCu2.9Mg0.1Ti4.2-xGexO12 ceramics with x = 0, 0.1, and 0.2 were fabricated to study the electrical and dielectric properties, nonlinear current–voltage properties, humidity sensing properties. The main phase of CaCu3Ti4O12 (CCTO) was obtained in the sintered ceramics with dense microstructure and slight change in grain size. All sintered ceramics showed high dielectric permittivity (ε′ > 104) at frequencies below 105 Hz, while the loss tangent was reduced by a factor of 3 (from 0.034 to 0.010 at 1 kHz and 25 °C), as x increased from 0 to 0.1. The temperature dependence of ε′ was also reduced. Furthermore, the enhanced nonlinear coefficient (α = 4.8–5.9) and breakdown electric field (Eb = 227–755 V/cm) were achieved. The dielectric and nonlinear properties originated from the electrically heterogeneous microstructure, which was confirmed by impedance and admittance spectroscopies. Both the resistance and activation energy of the insulating internal barriers were higher than that of the semiconducting core grains. Furthermore, these two parameters of the doped samples were larger than that of the undoped sample (x = 0). It was found that a low frequency ε′ was strongly dependent in the relative humidity in the range of 11–95 %RH, which could be applied in a humidity sensor. Accordingly, the hysteresis error was also calculated to determine the possibility of application in humidity sensors.

Experimental Investigation and Treatment Methods for Temperature, Water Droplets, and Carbon Atoms Effect on Transformer Oils

This article adheres to oil purity standards, investigating the impact of temperature, water, and carbon contaminants on transformer oils. The research employed breakdown voltage (BDV) and dissipation factor (DF) tests concerning IEC standards. Further, this article provided superior valuable insights into the behavior of transformer oils under different conditions and offered practical solutions for maintaining their optimal performance. The results highlighted that as temperature increased, the BDV of the oils decreased, underscoring the importance of maintaining adequate cooling in transformers. The presence of water droplets within the oil lowered the BDV and increased the DF. However, a treatment method involving a vacuum machine and nano-oil mitigated these adverse effects. Similarly, the presence of carbon atoms within the oil decreased the BDV and increased the DF. Still, the treatment method involving infrared radiation and titanium dioxide (TiO2) nanoparticles effectively improved the oil’s properties. In other words, the treatment method reduced carbon atoms’ effect on transformer oil through nano-oil, where the BDV and DF were performed on all samples before and after treatment to ensure the success of the treatment. Furthermore, a statistical analysis tool is employed to assess and evaluate the accuracy of the experimental test.

Probe with a metallic bowl termination to determine the electric material parameters from variable thicknesses

This paper discusses a new approach to determining the material electric parameters (dielectric constant and dissipation factor) through a technique based on identical material variation thicknesses. The copper bowl controls the material thicknesses and allows quick and safe measurements to get to the electromagnetic material information. This approach assumes that the discontinuities generated at the probe and bowl are identical and removed through mathematical operations. The material under test (MUT) gap thickness doesn’t exceed one millimeter. Some formulations have been developed to determine the discontinuity condensers and both capacitors of each thickness. Two proposed developments have been given to extract the complex effective and relative permittivities. A mathematical formula has been proposed to ensure the transition from effective to intrinsic parameters, where the MUT thicknesses and the probe’s outer diameter of the inner conductor are considered. A de-embedding operation is necessary, and the method is suitable but not limited to low-k. The coaxial probe is flat terminated, and the experimental validation has been made in the frequency ranges 1 MHz—2.2 GHz for FR-4 HTG-175 and 1 MHz—0.8 GHz for Alumina 99.5%. All MUTs are 5.0×5.0 cm2, except their thicknesses. The suggested approach is straightforward in sample insertion, simple in data acquisition and implementation, and precise in the final parameters’ results.

Density Functional Theory-Based Approach For Dielectric Constant Estimation of Soluble Polyimide Insulators.

Evaluation of the insulating properties of polymers, such as the dielectric constant and dissipation factor, is crucial in electronic devices, including field-effect transistors and wireless communication applications. This study applies density functional theory (DFT) to predict the dielectric constant of soluble polyimides (SPIs). Various SPIs containing trifluoromethyl groups in the backbone with different pendant types, numbers, and symmetries are successfully synthesized, and their dielectric constants are evaluated and compared with the DFT-estimated values. Two types of DFT-optimized SPIs, single-chain and stacked-chain models, are used to describe the local geometries of the SPIs. In addition, to reveal the relationship between the molecular structure and dielectric constant, further investigations are conducted by considering the dielectric constant of composing ionic and electronic components. The DFT-estimated static dielectric constant of the single-chain model accurately reproduces the corresponding experimental value with at least 80% accuracy. Our approach provides a rational and accelerated strategy to evaluate polymer insulators for electronic devices based on cost-effective DFT calculations.

Multi-expert GMM decision support system with AHP method for determining weight of transformer oil insulation quality index

The transformer is important and quite central in the power system for distributing energy from generators to consumers through electrical substations. Good transformer oil isolation is needed to protect the transformer to function optimally and prevent fatal interference. Over time, insulating oil experiences aging which can cause transformer damage and disruption in energy distribution to consumers. There are three things that affect the condition of transformer oil insulation, namely chemically testing for acidity, sediment (SED) and water content, from an electrical point of view testing for breakdown voltage (BDV) and testing dielectric dissipation factor (DDF), and from a physical point of view, color, and interfacial tension (IFT) tests are carried out. In dealing with this problem, a Decision Support System (DSS) is needed to calculate the oil quality index based on the given parameters. The method used is Analytical Hierarchy Process (AHP) with multi-expert GMM. The results show that the system is running well, and the calculation method is appropriate. Tests show 100% accuracy in comparing manual calculations with the Confusion Matrix system. Users give an average satisfaction of 92.94%. In conclusion, this system effectively meets the need and helps to determine the quality index of insulating oil in transformers.

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films