Wide Frequency Range Research Articles

Investigation of the interface state characteristics of the Al/Al2O3/Ge/p-Si heterostructure over a wide frequency range by capacitance and conductance measurements

In this work, Al/Al2O3/Ge/p-Si heterostructures were fabricated by e-beam thermal evaporation. The EDX (energy dispersive X-ray spectroscopy) map visually obtained the basic distribution information in a two-dimensional graph. Three-dimensional atomic Force Microscope (AFM) analysis of the roughness of the Al/Al2O3/Ge/p-Si heterostructure shows that the Al2O3 particle has approximately 4.35 nm. Quantitative analysis via histogram plots for Al2O3 interlayer grown on p-Si shows a Gaussian-like distribution, and it has a sharp profile between 0 and 2 nm on silicon, located around 1.2 nm. The current-voltage (I–V) and capacitance-conductance-voltage (C-G/ω-V) measurements were used to investigate the electrical properties of the structure at room temperature. The I–V measurements revealed two distinct linear regions, attributed to barrier inhomogeneity and distribution of interfacial state/trap densities (Dit). For this reason, we obtained Dit distributions by considering the voltage dependence of the ideality factor n(V) in two regions. Diode parameters acquired through different methods are comparatively presented with a brief literature review. Then, the C-G/ω-V measurements were conducted across a broad frequency range (from 0.3 kHz to 3 MHz), and these measurements revealed notable alterations in the electrical parameters with regard to frequency. In order to probe interface states/traps, we employed the conductance/admittance method, which provided satisfactory information about trap lifetime, following the low-high frequency (LF-HF) and Hill-Coleman methods. The effects of these states/traps on the measurements according to voltage, frequency, and energy level (Eit-Ev) are discussed in detail.

Identification of pressure pulsation spectrum in a hydraulic system with a vibrating proportional valve

In this paper, attention was focused on identifying the components of the amplitude-frequency spectrum of pressure pulsations in a hydraulic system in which an external low-frequency mechanical vibration was subjected to a proportional hydraulic directional control valve. It was observed that an operating machine or device equipped with hydraulic valves is a source of mechanical vibrations with a wide frequency spectrum. The influence of these vibrations on the pressure pulsation spectrum was analyzed, identifying the components resulting from the forcing of the directional control valve spool. In addition, it was noted that the pressure pulsation spectrum includes components resulting from the pulsation of the displacement pump output feeding the hydraulic system. A description of these spectrum components was also made and, using the solution superposition method, the components of the pressure pulsation spectrum over a wide frequency range were identified.

Theta Frequency Electromagnetic Stimulation Enhances Functional Recovery After Stroke

AbstractExtremely low-frequency, low-intensity electromagnetic field (ELF-EMF) therapy is a non-invasive brain stimulation method that can modulate neuroprotection and neuroplasticity. ELF-EMF was recently shown to enhance recovery in human stroke in a small pilot clinical trial (NCT04039178). ELF-EMFs encompass a wide range of frequencies, typically ranging from 1 to 100 Hz, and their effects can vary depending on the specific frequency employed. However, whether and to what extent the effectiveness of ELF-EMFs depends on the frequency remains unclear. In the present study, we aimed to assess the efficacy of different frequency-intensity protocols of ELF-EMF in promoting functional recovery in a mouse cortical stroke model with treatment initiated 4 days after the stroke, employing a series of motor behavior tests. Our findings demonstrate that a theta-frequency ELF-EMF (5 Hz) effectively enhances functional recovery in a reach-to-grasp task, whereas neither gamma-frequency (40 Hz) nor combination frequency (5–16-40 Hz) ELF-EMFs induce a significant effect. Importantly, our histological analysis reveals that none of the ELF-EMF protocols employed in our study affect infarct volume, inflammatory, or glial activation, suggesting that the observed beneficial effects may be mediated through non-neuroprotective mechanisms. Our data indicate that ELF-EMFs have an influence on functional recovery after stroke, and this effect is contingent upon the specific frequency used. These findings underscore the critical importance of optimizing the protocol parameters to maximize the beneficial effects of ELF-EMF. Further research is warranted to elucidate the underlying mechanisms and refine the protocol parameters for optimal therapeutic outcomes in stroke rehabilitation.

Regulation of microwave absorbing performance of magnetic alloy/ferrite/carbon ternary composites by changing polydopamine-induced carbothermal reduction

Magnetic alloy/ferrite/nitrogen-doped carbon composites (CoFe/CoFe2O4/N–C) spheres were synthesized by controlled carbothermal reduction of Co-doped Fe2O3 nanospheres wrapped in polydopamine. Different dopamine hydrochloride dosages not only affected components and nanostructures, but also regulated the electromagnetic properties of CoFe/CoFe2O4/N–C composites. The results show that with the increase of dopamine hydrochloride dosage, graphitic degree of N-doped carbon layer would decrease after an initial increase, while the Ms values exhibit an opposite trend. All samples show similar μr spectra, and negative μ″ values can be obtained at high frequency, which should be related to eddy current and dielectric resonance. With the increment of polydopamine, εr would first increase due to generation of CoFe and the increase in graphitic degree, and then decrease owing to the agglomeration of spherical particles. Further research on microwave absorption shows that RL peak frequency coincides with the frequency of perfect impedance matching when good impedance matching has been achieved across a wide range of frequencies. Thanks to the synergistic effects of conduction loss, interfacial polarization, dipole polarization, natural resonance, eddy current, and complete interference cancellation, S-100 has a wide effective absorption bandwidth of 4.88 GHz at 2.0 mm and a low RL peak value of −70.48 dB at 1.95 mm. This work could offer new insights into multi-component magnetic MAMs design and illuminate the relationships between reflection loss, impedance matching, interference cancellation, phase composition, and composite structure.

Experimental evidence of nonreciprocal propagation in space-time modulated piezoelectric phononic crystals

A nonreciprocal system composed of a one-dimensional piezoelectric phononic crystal whose periodic electrical conditions are modulated in time is presented. One-way longitudinal wave propagation is studied experimentally and compared to finite element temporal simulations. The modulation is performed by prescribing grounded or floating potential conditions on a periodic set of electrodes through external circuits. This approach makes it possible to consider a wide range of modulation speeds, and the large number of unit cells of the phononic crystal allows us to characterize experimentally the full dispersion curves of the system. This permits to observe the presence of directional bandgaps and to follow the shift in frequencies of these bandgaps as a function of the modulation speed. The experiments show the linear evolution of the central position of the bandgaps with the increase in the modulation speed, as well as their progressive closure, over a wide range of frequencies. Experiments are also used to estimate the evolution of bandgaps in a dispersive system, a problem discussed in several theoretical works but never observed experimentally. This work may constitute the foundation for experimental analysis of Floquet acoustic metamaterials, accelerated-modulation space-time metamaterials, or acoustic analog of the event horizon.

Multiband terahertz metamaterial perfect absorber for microorganisms detection

We report a multi-resonant terahertz (THz) metamaterial perfect absorber (MPA)-based biosensor in the working frequency range of 0 - 3.8 THz for sensing of microorganisms (such as fungi, yeast) and wheat pesticides. Nearly 100% absorption is realized at f_1= 1.7THz, f_2= 2.8THz, f_3=3.2THz, and f_4=3.5THz. We designed our THz MPA sensor making resonators’ gap area compatible with the microorganisms’ size. To obtain optimum performance of the MPA, a mapping of amplitudes and shifts in the absorption resonance peaks with different structural parameters of the resonators is carried out. A very high-frequency shift is obtained for microorganisms such as Penicillium chrysogenum (fungi), yeast, and pesticides (Imidacloprid, N, N-Diethyldithiocarbamate sodium salt trihydrate, Daminozide, N, N-Diethyldithiocarbamate sodium salt hydrate, and Dicofol). An equivalent circuit model using Advance Design System (ADS) software is developed. The calculated results through the model show similar trends as obtained in the simulations using CST. Investigations of the effect of incidence angle of THz wave on the absorption spectra of the MPA are also carried out. It is found that incidence angle does not impact the stability of the lower resonance absorption peak (1.79THz). Due to the wide working frequency range, the proposed sensor is extremely suitable for the detection of all range of pesticides because their specific absorption fingerprint lies in the frequency range of 0–3.8THz. We believe that our sensor could be a potential detection tool for detecting pesticide residues in agriculture and food products. The THz MPA-based biosensor is capable of detecting a very small change in the effective dielectric constant of the MPA environment. Therefore, it can also offer huge opportunities in label-free biosensing for future biomedical applications.

Numerical Study of the Time-Periodic Electroosmotic Flow of Viscoelastic Fluid through a Short Constriction Microchannel.

Electroosmotic flow (EOF) is of utmost significance due to its numerous practical uses in controlling flow at micro/nanoscales. In the present study, the time-periodic EOF of a viscoelastic fluid is statistically analyzed using a short 10:1 constriction microfluidic channel joining two reservoirs on either side. The flow is modeled using the Oldroyd-B (OB) model and the Poisson-Boltzmann model. The EOF of a highly concentrated polyacrylamide (PAA) aqueous solution is investigated under the combined effects of an alternating current (AC) electric field and a direct current (DC) electric field. Power-law degradation is visible in the energy spectra of the velocity fluctuations over a wide frequency range, pointing to the presence of elastic instabilities in the EOF. The energy-spectra curves of the velocity fluctuations under a DC electric field exhibit peaks primarily beneath 20 Hz, with the greatest peak being observed close to 6 Hz. When under both DC and AC electric fields, the energy spectra of the velocity fluctuations exhibit a peak at the same frequency as the AC electric field, and the highest peak is obtained when the frequency of the AC electric field is near 6 Hz. Additionally, the frequency of the AC electric field affects how quickly the viscoelastic EOF flows. Higher flow rates are obtained at relatively low frequencies compared to under the DC electric field, and the greatest flow rate is found close to 6 Hz. But as the frequency rises further, the flow rate falls. The flow rate falls to a level below the DC electric field when the frequency is sufficiently high.

Considering flexible wheel-rail coupling effects: An analysis of the vibration and transmission characteristics of damped track

The vibration and transmission characteristics of track components during vehicle operation is a complex issue. To address this issue, this paper proposes a flexible wheelset-damped track-tunnel-soil model that considers the interaction between the flexible wheelset and the rail. Using field measurements and the developed model, this study investigates the vibration characteristics of track components and explores the influence of fastener stiffness and damping pad stiffness on track vibration and vibration transfer characteristics between components from an energy perspective, using track spectrum power flow as the evaluation index. The results demonstrate that the model considering wheel-rail coupling can more comprehensively reflect the vibration characteristics of the track during train operation. Compared to fasteners with lower stiffness, damping pads with lower stiffness can reduce track vibration in a wider frequency range. Lower fastener stiffness reduces the transmission of vibration in 50∼2000 Hz, while lower damping pad stiffness reduces the transmission of vibrations in 1∼2000 Hz.

Validation of a Mathematical-Based Model for the Rheological Characterization of Asphalt Mixtures

Asphalt mixtures are viscoelastic materials whose behavior is highly dependent on temperature and loading frequency. The influence of these factors is described through master curves constructed at a given reference temperature based on the principle of frequency-temperature superposition. These curves are used as inputs in asphalt pavement design procedures based on mechanistic principles and related to their in-service pavement performance. This paper proposes the application of the Kramers-Kronig (K-K) relations to characterize the rheological properties of asphalt materials using a mathematical approach. Due to the complexity of the integration of the K-K relations, an approximate solution of the K–K relations was used to develop a Mathematical-Based Model to predict the master curves for the Dynamic Modulus |E*| and the Phase Angle f. This model was validated using the experimental results of two different asphalt mixtures with different characteristics. The results indicate that the model is accurate, and could be an effective approach to mathematically predict the master curves of the asphalt mixture viscoelastic properties in a wide range of temperatures and frequencies.

Kinematic response of pile groups and piled rafts to a distant stationary or moving harmonic load via the FEM

Using the finite-element method (FEM), this study presents results on piled foundations excited by a stationary or moving harmonic vertical point load acting on the soil surface at a given distance. For the stationary loading case, typical configurations of pile groups and corresponding piled rafts are examined in the frequency domain. The contribution of the raft alone in the overall response is also explored. The soil is modelled as a linear-elastic continuum with hysteretic damping. A wide range of frequencies from 8 to 64 Hz is considered. Of interest is the resulting vertical oscillation mode. The influence of the number of pile rows in the direction of wave propagation on the resulting vibration reduction is assessed by monitoring a reference pile at the furthest back pile row and an observation point at the free-field behind. The associated wave-passage effect is quantified through appropriate transfer functions for the piles. Subsequently, the case of a harmonic load travelling with a constant speed parallel to the pile group is investigated. Most importantly, it is revealed that a good approximation for this case is a stationary load located on the moving load path at the shortest distance from the pile group. This has important implications in the vibration protection practice, as detailed modelling of moving loads is then not required. The methodology presented can be extended to arbitrary foundation geometries and layered soil profiles.

Dielectric, electrochemical and magnetic properties of the hydrothermally synthesized double perovskite La2NiMnO6 for energy storage applications

Double perovskite materials are greatly appealing because of their multiferroic properties. Among such materials, double perovskite with rare earth metals are widely studied by researchers. Presently, the double perovskite La2NiMnO6 (LNMO) samples are synthesized using the hydrothermal method by varying the concentration of the solvent (NaOH). The Powder X-ray diffraction analysis confirmed the formation of monoclinic structure with the P21/n space group for prepared LNMO samples. The SEM image of the prepared samples revealed a cube-like structure. The impedance, dielectric, AC conductivity and modulus are studied in a wide frequency range from 100 Hz to 5 MHz to analyse the electrical and microstructure properties of the synthesized LNMO samples. The presence of a non- Debye type of relaxation peak is confirmed by impedance, dielectric and modulus studies. The effect of grains and grain boundaries are analysed by the Nyquist plot and the polarization of the materials are explained by the Maxwell-Wagner interfacial polarization model and Koop's theory. Using a three electrode system, the electrochemical behaviour of prepared LNMO samples are studied in various concentration of electrolyte (KOH) at different scan rates and found to have a pseudocapacitive nature. The highest specific capacitance value for LNMO10 is 44.60 F/g, LNMO20 is 50.14 F/g and LNMO30 is 25.81 F/g at a scan rate of 10 mV/s for 3 M KOH. The room temperature magnetic behaviour of synthesized LNMO samples analysed by Vibrating Sample Magnetometer paves way for magnetic storage applications.

Stator current signal crossing for fault diagnosis of self-excited induction generators

This paper presents a novel method for modelling and diagnosis of electrical and mechanical faults in fixed-Speed Self-Excited Induction Generators (SEIGs) operating in autonomous mode in a small-scale wind energy system. The proposed method is validated using the finite element method. After the selection of the magnetising capacitors, the self-excitation process is performed under no-load conditions. Once the stator voltage is established, a symmetrical three-phase load is connected. The fault detection method introduced here is called Stator Current Signal Crossing (SCSC). The SCSC extracts a new signal from the stator currents, that enables the detection of stator inter turn shortcircuits, broken rotor bars, and dynamic eccentricity faults in SEIGs. A spectral analysis of SCSC using the Fast Fourier Transform (FFT) algorithm is used to precisely locate the induced fault components. What sets this fault-tracking method apart from its predecessors is its exceptional ability to detect faults of any magnitude by analysing the modulation of the SCSC signal. These faults are directly identified by the presence of distinct harmonics, each indicative of a specific type of fault. This study also focuses on the SEIG in a wind energy system, whereas previous works have mainly addressed the induction machine in motor mode. In contrast, previous methods involved analysing a single current signal and isolating specific harmonics from a wide frequency range. The effectiveness of the proposed fault detection method and the self-excitation process are illustrated by simulation results and spectral analysis.

Synthesis of nanosized spinel ferrites MnFe2O4 on the surface of carbon nanotubes for the creation of polymer composites with enhanced microwave absorption capacity

Currently, the creation of new protective materials able to absorb the electromagnetic (EM) radiation is an important direction strongly linked to the use of high-tech electronics which leads to EM pollution in a wide range of high frequencies. The wide-band absorption and large bandwidth are two important factors affected the absorbing performance of materials. In this research, the development of polymer nanocomposites based on the multi-walled carbon nanotubes (CNTs) as a conductive component modified by manganese ferrite (MnFe2O4) nanoparticles as a magnetic component made it possible to increase the efficiency of absorption of EM waves in the frequency range 1–41 GHz as a result of good impedance matching characteristics in comparison with pure manganese ferrite. Finally, the absorption coefficient of EM waves in the frequency range of 5–20 GHz for MnFe2O4/0.065 vol.%CNT nanocomposites about 2.5–3 times higher than for MnFe2O4. The present work shows, that the introduction of MnFe2O4/CNT composites into the both amorphous (epoxy resin) and crystalline (polychlorotrifluoroethylene) polymer matrices makes it possible to manage microwave absorbing properties as well as a shift of the region of frequencies of maximum peak values of the absorption coefficient and reflection loss. The obtained relations prove that by the change of the amount of the modifying component (MnFe2O4) on the surface of carbon nanotubes, the content of the MnFe2O4/CNT nanocomposite in the polymer matrixes, and the thickness of the polymer composites it is possible to control the absorption coefficient and reflection loss of EM waves in the high frequency range. The MnFe2O4/0.044CNT–PCTFE and MnFe2O4/0.065CNT–epoxy resin composites exhibit higher bandwidth in relation to other reported composites or structures at the same thickness.

Broadband metasurface based on metallic stereo split-ring structure for full-space terahertz beam deflection and focusing effect

In this paper, we proposed an all-metal metasurface that enables circular polarization (CP) conversion and wavefront manipulation of the both transmitted and reflected terahertz (THz) waves over a wide frequency range. The proposed metasurface consists of a periodic array of the metallic stereo split-ring (MSSR) structure adhered on an ultrathin dielectric substrate made of benzocyclobutene (BCB). Numerical simulations show that the incident CP waves through the proposed MSSR can be converted into their orthogonal components in the full-space in a broadband range, with transmission conversion coefficients exceeding 40 % and reflection conversion coefficients exceeding 50 % between 0.8 and 1.1 THz (relative bandwidth of 31.6 %). Based on the geometric phase principle, 2π-phase full coverage can be realized by changing the rotation angle of the MSSR structure in the operating frequency range. Specifically, to demonstrate the multifunctional wavefront manipulation, we numerically simulated the anomalous deflection of THz beams and the full-space planar focusing functionality, respectively. Our research provides a valuable reference for the study of multifunctional components that possess full-space amplitude and phase modulation capabilities. This work holds particular significance in the field of device research in the THz region.

New porous absorber simulation techniques in the context of finite element modelling

Porous liners are widely used as vibration and acoustics isolation materials due to their high absorbing qualities in a wide frequency range. In a car body porous plates are laid on top of a metal structure to prevent vibroacoustic wave propagation inside the passenger cabin. Unfortunately, currently used FEM (finite element method) simulation models for poroelasticity Biot's equations are still unable to efficiently describe such coupled structure-liner-fluid systems due to the lack of modelling precision. The current paper focuses on the importance of the phenomena taking place on the structure-liner interface during dynamic excitations in the frequency range of 10-1000 Hz. Measurements of transfer functions for numerous foam samples with varying boundary conditions have been conducted in a vacuum chamber to estimate the effect of interface conditions. New simulation approaches are presented to account for the observed phenomena. Moreover, the issues of measurement uncertainties regarding foam material parameters (or Biot parameters) and poor measurement reproducibility have been addressed and corresponding parameter optimization schemes have been implemented. As a result, a significant improvement in the agreement between simulation and measurement results has been achieved. All simulations have been conducted in a custom FEM code based on the open-source Deal II library.

Effect of pulsed current cathodic protection on pipeline steel API 5L X65 corrosion mitigation: An investigation and machine learning-assisted modeling

Pulsed current cathodic protection (PCCP) could be more effective than direct current cathodic protection (DCCP) for mitigating corrosion in buried structures in the oil and gas industries if appropriate pulsed parameters are chosen. The purpose of this research is to present the corrosion prevention mechanism of the PCCP technique by taking into account the effects of duty cycle as well as frequency, modeling the relationships between pulse parameters (frequency and duty cycle) and system outputs (corrosion rate, protective current and pipe-to-soil potential) and finally identifying the most effective protection conditions over a wide range of frequency (2–10 kHz) and duty cycle (25%-75%). For this, pipe-to-soil potential, pH, current and power consumption, corrosion rate, surface deposits and investigation of pitting corrosion were taken into account. To model the input-output relationship in the PCCP method, a data-driven machine learning approach was used by training an artificial neural network (ANN). The results revealed that the PCCP system could yield the best protection conditions at 10 kHz frequency and 50% duty cycle, resulting in the longest protection length with the lowest corrosion rate at a consumption current 0.3 time that of the DCCP method. In the frequency range of 6–10 kHz and duty cycles of 50%-75%, SEM images indicated a uniform distribution of calcite deposits and no pits on cathode surface.

Numerical modelling of dual function tanks for fire suppression and tuned liquid damper applications

Exceeding serviceability limits due to wind-induced motions in tall buildings can cause discomfort for residents and adversely affect auxiliary building services, such as elevator operations. A tuned liquid damper (TLD) is an attractive type of dynamic absorber because of its simplicity and affordability. However, its dimensions and geometry can be limited by available floor space. Utilizing dual-purpose water tanks for both damping and fire suppression purposes can be a feasible resolution to fire code requirements and building motion control. Several design criteria need to be considered to accommodate the fire code requirements and the proper tuning of the TLD. Consequently, in this study, a TLD tank is fitted with a perforated floor to divide it into two compartments that allow water transmission to meet fire code requirements. However, the sloshing motion within the tank is complex and computationally expensive to capture when using traditional simulation models. This paper presents a 2D ISPH code equipped with a macro-level model to capture the effect of the perforated floor on the overall sloshing response of the tank. The model is first evaluated using existing results from previous studies on tanks with horizontal baffles. Next, the ISPH model is used to numerically model the perforated floor using the Ergun resistance (ER) macro-level model. In addition, the perforated floor is also explicitly micro-level modelled using rigid boundary particles to validate the proposed ER model. A numerical analysis is then conducted under different excitation amplitudes and frequencies, with both time history and frequency response results being presented. A structure-TLD model is subsequently used to capture the structure-TLD system response under random excitation. Results show that the ER model can efficiently model tanks with dual functions under both harmonic and random excitation and across a wide range of amplitudes and frequencies, with appreciable computational time savings. The proposed tank with a perforated floor is found to be effective in serving as a dual-purpose TLD and storage tank for fire suppression in buildings.

An analytical approach for the analysis of stress wave transmission and reflection in waveguide systems based on Timoshenko beam theory

The paper presents an analytical continuous solution for the analysis of wave refraction and transmission/reflection caused by arbitrarily complex waveguide subsystems. It allows analyzing the way stress wave components are altered as they go through a substructure. The method is new in that it investigates the wave phenomena which govern the dynamic behavior of a structural system explicitly and studies the effectiveness of different serrated and fractal subsystem designs functioning as wave content filters. Timoshenko beam theory is used to model stress wave propagation in waveguides because of its accuracy and consistency over a wide range of vibration frequencies. The versatility of the method is demonstrated using a number of numerical examples characterizing stress wave refraction in single input/single output and single input/multiple output subsystems to study periodic, fractal, and serrated forms. The low computation cost and stable accuracy of the method over a very wide range of frequencies, make it an effective tool for metaheuristic optimization approaches which require massive calculations over many generations. The method is demonstrated to perform seamlessly in coupling with a genetic algorithm optimization framework to determine the optimal serrated configuration of a wave filter.

Synthesis of prussian blue analog (Co/TCNi/HCCr) nanoparticles using a facile co-precipitation approach and evaluation of their dielectric characteristics for electronic applications

The Prussian blue analog Co0.4/(TCNi)0.2/(HCCr)0.6 (PBA) nanoparticles were synthesized via a chemical co-precipitation approach. The structural characteristics of the nanocomposite (NCp) were investigated using the XRD technique, which revealed that the synthetic PBA has a tiny crystallite size and poor crystallinity. The XRD analysis suggests that the fabricated NCp has a face-centered cubic structure with space group Fm-3 m. For deep microstructure analysis, SEM, EDX, and AFM were employed to describe the topological nature and surface architecture. It is observed that the PBA nanocomposite has a small crystallite size of ~13.66 ± 0.32 nm. The particles’ surface displays a high degree of homogeneity, while the grain boundaries are clearly discernible, presenting a spherical morphology with an average diameter of 22 ± 2.1 nm. The porosity was ascertained from an AFM image of approximately 140. Furthermore, the value of the average roughness (Rs) is 6.86 nm. The AC conductivity of PBA in disc form was calculated at various temperatures and frequencies. The results indicate that the dielectric constant (ɛ′) of PBA nanoparticles exhibits a rise from 163 to 3464 throughout the frequency range of 10–100 kHz at ambient temperature and from 27 to 6000 at 293 K. This finding provides confirmation that the dielectric characteristics of PBA nanoparticles are enhanced during the process of annealing. The values of the exponent factor (s) range from 0 to 1; this behavior is connected to the correlated barrier hopping model (CBHM) for AC conductivity. The value of WM was ascertained to be 1.69 eV. Furthermore, the values of activation energy were calculated, and these values decreased from 0.20 to 0.17 eV with annealing. The change in loss tangent (tanδ) as a function of angular frequency at various temperatures is also shown. The investigation of the dielectric characteristics was measured over a wide range of frequencies and temperatures to get valuable data about the dissipation properties of the prospective electronic applications.

Upgraded Full multiple reflections method improves accuracy in Time-Domain dielectric spectroscopy

Automated measurements of the dielectric properties of matter, based on Time-Domain Dielectric Spectrometry, have been used for several decades. In this paper, we report and evaluate a novel Full Multiple Reflections algorithm for extracting the material-under-test complex dielectric permittivity, able to perform over a wide range of frequencies. The novel method is based on the analysis of multiple reflections due to non-idealities and unintended impedance mismatches in the transmission line, to extract their influence on the final result. The method is compared against two classic strategies and proves to be more accurate, while overriding the well-known drawbacks of using non-ideal transmission lines. Limitations of the method are discussed and tested through representative results using materials widely studied and researched in the literature.