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We report on temperature-dependent dielectric behavior of disordered ternary A6B2O17 (A = Zr, Hf; B = Nb, Ta)-form oxides in the GHz frequency range. The microwave dielectric properties including relative permittivity, dielectric loss, and temperature-dependent relative permittivity were characterized using cylindrical dielectric resonators using a resonant post measurement technique. Dielectric measurements through the resonant post method approach generally agree with dielectric measurements of A6B2O17 bulk ceramics measured through standard resonant post techniques. Coefficients describing the temperature-dependent relative permittivity for ternary A6B2O17 phases are strongly positive, suggesting contributions to polarizability arising from long-range mechanisms potentially associated with structural disorder. These observations support the working hypothesis that material functionality can be engineered by the chemical diversity and structural disorder possible in high configurational entropy A6B2O17 phases. [ABSTRACT FROM AUTHOR]

Manganese oxides with spinel structure could exhibit abundant physical effects due to the complex sublattice structure, variable valence states and the intricate roles of manganese cations in magnetic interaction. In this work, NiMn 2 O 4 ceramic with space group of Fd 3 ‾ m is synthesized. The low-temperature polarization behavior is investigated accompanied by revealing the multi-stage dielectric relaxation. Moreover, the relaxation mechanism is confirmed through microstructure characterization, multiple-condition pyroelectric measurement and the dielectric tunability properties under electric/magnetic fields. With increasing measuring temperature, different relaxation phenomena are respectively induced by lattice distortion because of the competition among magnetic coupling interactions (below ∼135 K), electron hopping relating to the coexistence of different valence states of manganese ions (∼135–230 K), and the synergistic contribution of oxygen vacancies and domain wall effect (above ∼230 K). These results provide additional evidence for comprehensive understanding the low-temperature polarization in NiMn 2 O 4 , guiding the method design for exploring the physical origin within a wide temperature range. [ABSTRACT FROM AUTHOR]

In this manuscript, a new method for the synthesis of CaCu 3 Ti 4 O 12 (CCTO) perovskite was adopted via co-precipitation followed by calcination processes. The co-precipitation route was employed to synthesize calcium and copper oxalates precipitated on the TiO 2 surfaces and the calcination technique at different temperatures was utilized to follow the single-phase formation. Differential thermal analysis-thermogravimetry (DTA-TG) were used to estimate the proper calcination temperatures and to follow the precursor′s decomposition stages. X-ray diffraction (XRD) revealed the initiation of titanate formation at 700 °C. The complete formation of single-phase was achieved at 1100 °C. In agreement with the XRD measurements, FT-IR spectra confirmed the formation the different phases at different calcination temperatures. The prepared titanate showed giant dielectric properties with values higher than reported in literature. The conductivity measurement indicated semi-conducting properties and revealed a transition agreed well with that obtained in the dielectric properties measurements vs. temperature, attributed to the orientional polarization or change in the entire conduction mechanism from hopping to ionic conduction. The obtained electrical properties enhances the utilization of the entire titanate as capacitors. [ABSTRACT FROM AUTHOR]

Pure anatase TiO 2 nanoparticles and its mono–doped and co–doped derivatives [i.e. (TiN 0.007 O 1.993); (Ti 0.998 Cu 0.002 O 2); (Ti 0.998 Cu 0.002 N 0.007 O 1.993)] were prepared by sol–gel auto–combustion technique. Further, the effects of copper (Cu) and nitrogen (N) dopants have been investigated on structural, optical and dielectric properties of nanostructured TiO 2 using X–ray diffraction (XRD), Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy and dielectric spectroscopy measurement respectively. The Rietveld refinement analysis of XRD data and Raman spectra revealed that all the synthesized samples have pure anatase phase having tetragonal structure with space group of I 4 1 / amd. The pure anatase phase of doped samples illustrate the substitution of Cu ions at Ti4+ sites and N ions at O2− sites in the TiO 2 host lattice. The crystallite size of TiO 2 and its derivatives has been observed in the range of 11–14 nm. The band gap of TiO 2 reduced from 3.2 to 1.9 eV with mono–doping and co–doping of the N and Cu in TiO 2 lattice as confirmed by UV–Vis spectroscopy. This red–shift might be occur due to the possible formation of N–2p and Cu–3d localized levels (mono–doping case), and the creation of isolated intermediate states (co–doping case). The dielectric spectroscopy was carried out to investigate the electrical properties in details and explained in terms of structural and intrinsic ionic behaviour of different dopants. The detected band gap energies in N/Cu mono–doped and co–doped anatase TiO 2 fall within the visible spectrum, rendering them suitable for harnessing solar energy in photocatalysis and photovoltaic applications. [Display omitted] • Synthesis of mono–doped and co–doped TiO 2 by Cu (0.2 mol%)/N (0.7 mol%) ions • Doping was performed using sol–gel method whilst retain anatase phase • Red–shift due to formation of N–2p and Cu–3d localized levels in mono–doping • Red–shift ascribed to isolated intermediate band formation in co–doping • Enhancement in conductivity for co–doping as compared to pure and mono–doping [ABSTRACT FROM AUTHOR]

A series of Mg doped ZCFAO (Zn0.3−xMgxCu0.7Al0.3Fe1.7O4 (0.05 ≤ x ≤ 0.25) spinel samples were synthesized by solid state reaction method. XRD, was utilized to investigate the structure phase, microstructural characteristics, The optical properties were analyzed; Biological instruments Sp-150 potentiostate is employed to investigate the dielectric measurements in the frequency range of 10 Hz to 1 MHz at various temperatures from 300 to 650 K. Vibrating sample magnetometer VSM was employed to examine the magnetic characteristics in the applied magnetic field ranging from − 20 to 20 kG. The creation of a single-phase cubic spinel was validated by X-ray analysis. The leverage of replacing Zn by Mg leads to enhancement in the lattice parameters, reducing both of the degree of inversion, crystal distortion and compelled these samples to be normal spinel. It turned out that as the degree of inversion sank, the crystallite size declined. The values of dislocations density was found in the order of 10−5 which reveal improving and completing the crystallization of the ferrite samples. The samples have an optical energy gap in the range 3.1–3.38 eV, according to the inferred optical characteristics. The dielectric constant revealed the normal behavior of spinel ferrite it decreases with increasing frequency and enhanced with increasing temperature. It seems that the microstructure of the compound consists of both high-conductive grains and low-conductive grain boundaries, which has been confirmed by the complex impedance. Additionally, the presence of the Maxwell–Wagner relaxation process is also detected. This information can provide valuable insights into the properties and behavior of the compound. Using Nyquist plot, the sample impedance characteristics were interpreted while taking grain and grain boundary contributions into account. The magnetic properties proved that doping ZCFAO with diamagnetic cations (Mg) increases both of saturation magnetization from 16.416 up to 29.983 emu/g and the magnetocrystalline anisotropic constant from 1319.24 to 1612.804 because the two main factors that influence the magnetic properties are the distribution of cations between the octahedral and tetrahedral sites and the magnetic moment of each of its cations. Novelty of our work replacing Zn by Mg (both of them diamagnetic materials) enhance the magnetic properties. Synthesized materials may reexamine the mechanisms underlying Mg2+ induced cationic exchange in ZCFAO and have prospective uses as soft-magnetic materials. [ABSTRACT FROM AUTHOR]

Non-linear optical materials have greatly impacted science and technology in recent years. In the present work, crystals of amino acid derivative l-histidinium acetate dihydrate (L-HA) were grown using the gradual evaporation method. The powder-crystal X-ray diffraction (PXRD) technique was applied to examine the phase composition of the crystal sample. The XRD analysis showed that the L-HA was crystallized into the triclinic system. Microstructural parameters were evaluated, including dislocation density and micro-strain induced in the samples. The vibrational modes of the L-HA crystal were found using confocal Raman spectrum analysis. UV–Vis spectral analysis was applied to ascertain the crystal's optical absorbance and transmittance. The bandgap and Urbach edge of L-HA were explored in the UV–Vis spectrum. The second harmonic generation potency of L-HA was examined using Kurtz–Perry analysis, and it was found that L-HA exhibited significant SHG efficiency. The dielectric and impedance characteristics of the L-HA were assessed in the 100 Hz‒5 MHz range at different temperatures. Dielectric measurements show that at frequencies higher than 10 kHz, the dielectric constant and dielectric loss are saturated at minimum levels. The Nyquist graph displays the negative temperature coefficient of resistance in the compound. Vickers microhardness analysis demonstrates the normal indentation size effect and hard nature of the L-HA sample. Thus, the L-HA crystals are suitable for optoelectronic applications due to their excellent optical characteristics, considerable SHG efficiency, and appropriate dielectric, impedance, and microhardness features. [ABSTRACT FROM AUTHOR]

The tetragonal tungsten bronze structural type (TTB) is one of the interesting family where the structure is compatible with a wide variety of cationic substitution that permits tailoring physical properties including ferroelectricity, piezoelectricity, nonlinear optics, and energy storage properties. Over the past years, major consideration was devoted to niobate based- tetragonal tungsten bronze, as promising materials for electronic components. In the present work, the conventional solid-state method was used to prepare samples within the NaNbO3−BaNb2O6−MoO3 system. The structural refinement performed by the Rietveld method and using GSAS-II software, showed that this sample is constituted by two crystalline phases namely Ba2Mo0.80NaNb4.20O15 and Ba2Mo0.40NaNb4.60O15. The first one crystallizes in the P4bm- tetragonal structure with cell parameters of a = b = 12.3762Å and c = 3.98587Å. However, the second was found to crystallize in the orthorhombic symmetry with Pba2 as space group and a = 12.5260 Å, b = 12.42936 Å, and c = 3.97861 Å. Raman spectroscopy was used to get complementary comments on the structure of the BNMO ceramic. The dielectric measurements were carried out from 25 °C to 550 °C and in a frequency range of (10 Hz–1 MHz). [ABSTRACT FROM AUTHOR]

In this study, we used the solution casting process to produce polyvinyl chloride (PVC) polymer nanocomposites incorporated with ZnMn2O4/CuCo2O4 (ZMCC) and different tetramethylammonium iodide (TMAI) quantities. The PVC/ZMCC/x wt% TMAI polymers were characterized with several analytical techniques; x-ray diffraction, transmission electron microscope, UV–vis diffuse reflectance, photoluminescence (PL), and dielectric measurements. The results obtained from these techniques demonstrated an excellent interaction between the different fillers and the PVC matrix. The reflectance (R), transmittance (T), extinction coefficient (k), refractive index (n), optical dielectric constants, optical conductivity, energy loss functions and nonlinear optical parameters were analyzed. Upon composing with the fillers, T is reduced while A is enhanced for all composition ratios with minimum T and maximum A for the blend with 6 wt% TMAI. The optical energy gap declined from (4.29, 5.17) eV and (4.02, 4.79) eV to (3.04, 3.93, 5.01) eV and (2.43, 3.57, 4.22) eV for direct and indirect transition as the content of TMAI became 6 wt% in loaded polymer. Under varying excitation wavelengths, a blue-violet emission was observed in all the polymers. The effect of fillers on the dielectric constants, dielectric moduli, energy density, and AC conductivity were examined. The polymer with 6 wt% TMAI produced the highest AC conductivity, while the polymer with ZMCC has the highest capacitance. The Cole–Cole plot, obtained using a non-Debye technique, exhibited a semicircular shape. Hence, the improved optical and dielectric properties of the PVC/ZMCC/x wt% TMAI polymers nanocomposites suggest that these materials are suitable for smart electronic devices. [ABSTRACT FROM AUTHOR]

This article presents the research results of lead-free Ba1−3/2xLax(Fe0.5Nb0.5)O3 (BFNxLa) ceramic materials doped with La (x = 0.00–0.06) obtained via the solid-state reaction method. The tests of the BFNxLa ceramic samples included structural (X-ray), morphological (SEM, EDS, EPMA), DC electrical conductivity, and dielectric measurements. For all BFNxLa ceramic samples, the X-ray tests revealed a perovskite-type cubic structure with the space group Pm 3 ¯ m. In the case of the samples with the highest amount of lanthanum, i.e., for x = 0.04 (BFN4La) and x = 0.06 (BFN6La), the X-ray analysis also showed a small amount of pyrochlore LaNbO4 secondary phase. In the microstructure of BFNxLa ceramic samples, the average grain size decreases with increasing La content, affecting their dielectric properties. The BFN ceramics show relaxation properties, diffusion phase transition, and very high permittivity at room temperature (56,750 for 1 kHz). The admixture of lanthanum diminishes the permittivity values but effectively reduces the dielectric loss and electrical conductivity of the BFNxLa ceramic samples. All BFNxLa samples show a Debye-like relaxation behavior at lower frequencies; the frequency dispersion of the dielectric constant becomes weaker with increasing admixtures of lanthanum. Research has shown that using an appropriate amount of lanthanum introduced to BFN can obtain high permittivity values while decreasing dielectric loss and electrical conductivity, which predisposes them to energy storage applications. [ABSTRACT FROM AUTHOR]

In this study, we investigated the impact of Chromium substitution on the structural, dielectric and ferroelectric characteristics of Ba 0·90 Sr 0·10 Ti 1-3x/4 Cr x O 3 (x = 0, 0.005, 0.010, 0.015 and 0.020) ceramics fabricated by solid state reaction method. Rietveld refinement of X-ray diffraction pattern confirmed tetragonal perovskite structure for all the samples. Based on the crystal structure and the lattice parameter obtained through XRD measurement, the Madelung energy of each sample was computed. SEM images revealed a reduction in grain size with rising Cr concentration. TEM, HRTEM, SAED and EDS analysis was carried out for BST-Cr3 sample. Diffused rings observed in Selective Area Electron Diffraction (SAED) patterns indicate the crystallinity of the sample. EDS analysis indicated the presence of Ba, Sr, Ti, O and Cr elements. In the temperature range of 30 °C–150 °C, dielectric measurements (dielectric constant 'ε' and tangent loss 'tanδ') have been made at different frequencies (1, 10, 50, 100 and 1000 kHz). The samples displayed a diffused phase transition, with noticeable reduction in Curie temperature 'T c ' and tangent loss 'tanδ' with the substitution of Cr. Polarization versus electric field loops were recorded at different electric fields (5, 10, 15, 20 and 25 kV/cm) and improved values of remnant polarization 'P r ' and coercive field 'E c ' were observed. A lower E c value facilitates easier domain movement within the unit cell, leading to enhanced ferroelectric properties. Temperature dependent P-E loops indicated that as the temperature increased, the material became softer accompanied by simultaneous reduction in P r and E c values. [ABSTRACT FROM AUTHOR]

In recent years, environment-friendly lead-free dopants-incorporated Ba-based perovskite oxides have found their potential applications in electronic devices due to their improved performances by modifying the crystal structures. In this study, BCZT [Ba0.9Ca0.1Zr0.1Ti0.9O3], Bi-doped BCZT [(Ba0.9Ca0.1)0.925Bi0.05Zr0.1Ti0.9O3], Cu-doped BCZT [Ba0.9Ca0.1(Zr0.1Ti0.9)0.997Cu0.003O3], and Bi–Cu both doped BCZT [(Ba0.9Ca0.1)0.925Bi0.05(Zr0.1Ti0.9)0.997Cu0.003O3] were prepared by conventional solid-state reaction method to study the effect of doping from microscopic and atomic point of view. XRD and Rietveld techniques are used to identify and quantify the phases, respectively. FTIR study confirmed the modification of the cell parameters due to doping, based on its composition. Raman spectroscopy is used to study the nature of symmetry presence in BCZT ceramics before and after doping. It reveals the presence of trace amount of orthorhombic symmetry with Tetragonal in all samples, as well as little cubic symmetry observed in BCZT-Bi and BCZT-BiCu. FESEM is used to study the surface morphology along with different grains in BCZT with doping. Localized structural distortion originated by dopants was investigated by the Atomic Pair Distribution Function (PDF) method. Aside from average structure, PDF gives information about localized structure within short-range zone, which is significantly modified, whereas long-range structure is almost similar. PDF shows the Raman-predicted orthorhombic phase is not exactly orthorhombic but the distorted tetragonal phase. Ultraviolet–visible (UV–vis) spectra show the bandgap energy increased after doping in BCZT. Dielectric measurement of all samples shows a high dielectric constant (>2000), and it is shown that vacancy in the crystal plays an important role in the dielectric behavior with frequency. The average and atomic–scale structure of Bi/Cu and Bi–Cu doped BCZT helped to understand the dielectric behavior for potential application of the barium titanate complex perovskites. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the dielectric constant of solutions of a polar liquid in a nonpolar solvent: chlorobenzene–benzene, chlorobenzene–hexane. The measurements were carried out at a wavelength λ = 1 2. 8 0 cm in the temperature range from − 8 0 ∘ C to 2 0 ∘ C. The studies were carried out using the dielectric spectroscopy method. This method allows a more detailed study of the dielectric properties of the objects of study due to the large equilibrium ("static") dielectric constant of the object. The temperature dependence of the dielectric relaxation time of molecules in the liquid and solid states of the studied solutions is determined. It has been established that with increasing concentration (0.300, 0.562, 0.794, 1.000 for a chlorobenzene–hexane solution and 0.179, 0.368, 0.567, 0.778, 1.000 for a chlorobenzene–benzene solution) of the halogen substituent, the relaxation time increases. The measurement results of dielectric constant ε ′ and absorption coefficient ε ′ ′ obtained for concentrated solutions chlorobenzene–benzene, chlorobenzene–n–hexane at wavelengths λ = 1 2 , 80 and λ = 3 , 2 6 cm at temperature 2 0 ∘ C are given in the paper. The static dielectric constant is obtained at a frequency of 1 MHz. The obtained experimental values ε ′ , ε ′ ′ and ε 0 of investigated systems in ( ε ′ , ε ′ ′ ) plane locate on the semi-circle the center of which is on ε ′ axis. In this case, the high-frequency limit value of ε ∞ dielectric coefficient exceeds the corresponding n2 refraction index square. The macroscopic and molecular relaxation times are calculated on the base of experimental data. The thermodynamic quantities characterizing the process of dielectric relaxation are calculated for solutions of chlorobenzene–benzene, chlorobenzene–hexane. It has been determined that the height of the potential barrier separating the two equilibrium positions of a polar molecule is greatest in the state of a pure polar liquid and decreases with dilution in a nonpolar solvent. [ABSTRACT FROM AUTHOR]

The present work explores a systematic investigation of the microstructural, optical, and dielectric properties of W1−xNixO3 (x = 0, 0.02, 0.04, and 0.06) samples and their application in supercapacitors. The sol–gel auto-combustion process was used to synthesize these samples, and a number of analytical techniques such as x-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman, Scanning Electron Microscopy (SEM), UV–visible spectroscopy, dielectric measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to characterize them. The Rietveld refined XRD patterns confirm the monoclinic phase with space group P21/n in a single phase. FTIR spectroscopy confirms the functional groups associated with stretching and bending vibrational modes at various wavenumbers. Raman spectroscopy ensures the phase purity of the materials and shows a blue shift with Ni doping. SEM microscopy reveals a uniform surface morphology as well as particle agglomeration at the surface. UV–visible studies reveal a significant decrease in the bandgap (2.13–1.81 eV) as the Ni concentration is increased. Dielectric studies show that as the frequency rises, the dielectric constant decreases and becomes saturated at higher frequencies. The highest value of the dielectric constant (ε') is observed for the 4% Ni-doped WO3 sample. The electrochemical and capacitive properties have been characterized and studied using CV and EIS analysis. Cyclic voltammetry tests were carried out in the range of − 0.2 to 0.8 V with varying scan rates (5–100 mVs−1), exhibiting a significantly large area under the CV curve, hence higher values of specific capacitance. The maximum specific capacitance at a scan rate of 5 mVs−1 for each sample of W1−xNixO3 (x = 0, 0.02, 0.04, and 0.06) is found to be 126.671, 192.31, 278.52, and 128.58 Fg−1, respectively, in 2M KOH electrolyte. Thus, the synthesized samples exhibit potential for application as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

Microwaves can safely and non-destructively illuminate and penetrate dielectric materials, making them an attractive solution for various medical tasks, including detection, diagnosis, classification, and monitoring. Their inherent electromagnetic properties, portability, cost-effectiveness, and the growth in computing capabilities have encouraged the development of numerous microwave sensing and imaging systems in the medical field, with the potential to complement or even replace current gold-standard methods. This review aims to provide a comprehensive update on the latest advances in medical applications of microwaves, particularly focusing on the near-field ones working within the 1–15 GHz frequency range. It specifically examines significant strides in the development of clinical devices for brain stroke diagnosis and classification, breast cancer screening, and continuous blood glucose monitoring. The technical implementation and algorithmic aspects of prototypes and devices are discussed in detail, including the transceiver systems, radiating elements (such as antennas and sensors), and the imaging algorithms. Additionally, it provides an overview of other promising cutting-edge microwave medical applications, such as knee injuries and colon polyps detection, torso scanning and image-based monitoring of thermal therapy intervention. Finally, the review discusses the challenges of achieving clinical engagement with microwave-based technologies and explores future perspectives. [ABSTRACT FROM AUTHOR]

This paper presents a complete analysis of the electrical and dielectric characteristics of N i C o 2 O 4 (NCO) bulk ceramic synthesized by the co-precipitation process as a future electronic device material. The structural analysis following the synthesis process revealed the formation of cubic-phase spinel NCO in the shape of nanospheres, with an approximate diameter of 25 nm. The present study aimed to examine the relationship between capacitance and conductance for the NCO under investigation, focusing on their frequency and temperature dependencies. The frequency range of interest ranged from 100 Hz to 1.5 MHz, while the temperature range considered was from 300 K to 450 K. The C/f plot has exhibited the phenomenon of negative capacitance, which may be attributed to the augmentation of polarization and the incorporation of additional minority carriers inside the structure. The dielectric parameters, such as permittivity, dielectric loss, alternating current conductance, and electrical modulus, were determined by capacitance and conductance measurements, taking into account their frequency and temperature reliance. All dielectric calculations were influenced by negative capacitance measurements. The negative capacitance feature of N i C o 2 O 4 is attributed to the ferroelectric properties of the Ni and Co elements in its composition. In conclusion, this paper has made a valuable contribution to the existing body of literature by enhancing our comprehension of the negative capacitance behavior and dielectric characteristics of the NCO. [Display omitted] [ABSTRACT FROM AUTHOR]

Complex dielectric measurements were performed in 1-nitropropane (NTP) and DMSO mixtures at various concentrations in the frequency range of 10 MHz to 50 GHz using time domain reflectometry technique. The excess inverse relaxation time values were found to be negative, indicating that the dipoles rotated more slowly. Alenka Luzar's hydrogen-bonded theory is used to calculate theoretical estimates of the static dielectric constant. The variations in dielectric parameters such as dielectric constant, relaxation time, Kirkwood correlation factor and excess properties observed in the study confirm the existence of intermolecular interactions within the NTP-DMSO mixtures. [ABSTRACT FROM AUTHOR]

This paper presents accurate, prompt, and cost‐effective relative permittivity and loss tangent measurements of low‐loss dielectrics such as DuPontTM VESPEL® SP‐1 and VictrexTM polyetherketone (PEEK) 450G, which are commonly used materials in space communication antennas. It is essential for an antenna engineer to have the information regarding the electrical properties, that is, dielectric permittivity, dielectric loss tangent, magnetic permeability, and magnetic loss tangent at the frequency of interest. The test method relies on the accurate measurements of the S‐parameters of the sample under test by means of Through‐Reflect‐Line (TRL) calibration using a Vector Network Analyzer (VNA). Nicholson‐Ross‐Weir (NRW) method is employed to get the conversion from S‐parameters to both complex permittivity and permeability values of the samples. The experimental results are verified with the literature data of Teflon and relative permittivity and loss tangent measurements of VESPEL® SP‐1 (εr=3.119±0.043 ${\varepsilon }_{r}=3.119\pm 0.043$, tanδ=(20.893±4.042)*10−3 $\tan \delta =(20.893\pm 4.042)* {10}^{-3}$) and PEEK 450G (εr=3.119±0.015 ${\varepsilon }_{r}=3.119\pm 0.015$, tanδ=(5.654±1.877)*10−3 $\tan \delta =(5.654\pm 1.877)* {10}^{-3}$) are presented for X‐band (8‐10 GHz) frequencies. [ABSTRACT FROM AUTHOR]

The search for new materials and compositions, in which the phenomena of ferrimagnetism and ferroelectricity are closely coupled, is of great technological interest. In the present study, composite systems of (BaTiO 3) (100- x)% /(CoNb 0 · 02 Fe 1 · 98 O 4) x % where x = 0, 2, 5, 10, 20, and 100% were produced. Initially, BaTiO 3 (BTO) was made by sol-gel combustion approach and CoFe 1 · 98 Nb 0 · 02 O 4 (CoFeNbO) was made by hydrothermal method. Both compounds were then combined via solid-state reaction route to form the composite systems. According to X-ray diffraction, the pristine BTO and CoNbFeO display tetragonal and cubic structures, respectively, and all composite systems consisted of the cubic phase for BTO and spinel phase for CoNbFeO. Scanning electron microscopy showed a decrease in grain size (from 0.552 μm to 0.194 μm) and porosity (from 18.65% to 4.57%) as the CoNbFeO content increases from x = 0 to x = 20%, respectively. The influence of magnetic CoNbFeO content on the magnetic, ferroelectric, magnetoelectric coefficient, electric, and dielectric properties of composite systems has been investigated. The ferromagnetic and ferroelectric natures of diverse composite systems are reflected via the registered M-H and P-E loops at ambient temperature. A steady increase in magnetic parameters such as saturation magnetization and remanent magnetization is observed as the spinel ferrite CoNbFeO content increases. Similarly, the values of the electric coercivity increased from 1.65 kV/cm for x = 0% to 3.99 kV/cm for x = 20%. The frequency-dependent dielectric and electrical measurements were also investigated at various temperatures. By raising the measurement temperature, the dielectric polarization was found to increase for composite systems with x > 2%. Interestingly, the tangent loss was reduced for different composite systems in comparison to pristine BTO and CoNbFeO materials. The lowest tangent loss values were noticed for x = 5% composite system. All composite systems revealed good magnetoelectric coupling with coupling coefficient magnitudes up to a maximum value of ∼22.5 mV/cm.Oe, indicating that they can be potential candidates for use in advanced multifunctional electric devices. [ABSTRACT FROM AUTHOR]

A thorough understanding of the interplay between polarization mechanisms is pivotal for the interpretation of electrical measurements, since sub-megahertz electrical measurements in sedimentary rocks are dominated by interfacial polarization mechanisms. Nonetheless, rock-physics models oversimplify pore-network geometry and the interaction of electric double layers relating to adjacent grains. Numerical algorithms present the best possible framework in which to characterize the electrical response of sedimentary rocks, avoiding the constraints intrinsic to rock-physics models. Recently, an algorithm was introduced that can simulate the interactions of electric fields with the ions in solution. The sub-kilohertz permittivity enhancement in sedimentary rocks is dominated by Stern-layer polarization, but a model for the polarization mechanism associated with the Stern layer has not been developed. Hence, the aim of this paper is to develop and test a numerical simulation framework to quantify the influence of Stern- and diffuse-layer polarization, temperature, ion concentration, and pore-network geometry on multi-frequency complex electrical measurements. The algorithm numerically solves the Poisson–Nernst–Planck equations in the time domain and a mineral-dependent electrochemical adsorption/desorption equilibrium model to determine surface charge distribution. Then, the numerical simulator is utilized to perform a sensitivity analysis to quantify the influence of electrolyte and interfacial properties on the permittivity of pore-scale samples at different frequencies. [ABSTRACT FROM AUTHOR]

Cell dielectric property measurement holds significant potential for application in cell detection and diagnosis due to its label-free and noninvasive nature. In this study, we developed a biosensor designed to measure the permittivity of liquid samples, particularly cell suspensions at the nanoliter scale, utilizing microwave and millimeter wave coplanar waveguides in conjunction with a microchannel. This biosensor facilitates the measurement of scattering parameters within a frequency domain ranging from 1 GHz to 110 GHz. The obtained scattering parameters are then converted into dielectric constants using specific algorithms. A cell capture structure within the microchannel ensures that cell suspensions remain stable within the measurement zone. The feasibility of this biosensor was confirmed by comparison with a commercial Keysight probe. We measured the dielectric constants of three different cell suspensions (HepG2, A549, MCF-7) using our biosensor. We also counted the number of cells captured in multiple measurements for each cell type and compared the corresponding changes in permittivity. The results indicated that the real part of the permittivity of HepG2 cells is 0.2–0.8 lower than that of the other two cell types. The difference between A549 and MCF-7 was relatively minor, only 0.2–0.4. The fluctuations in the dielectric spectrum caused by changes in cell numbers during measurements were smaller than the differences observed between different cell types. Thus, the sensor is suitable for measuring cell suspensions and can be utilized for label-free, noninvasive studies in identifying biological cell suspensions. [ABSTRACT FROM AUTHOR]

Solid solutions of Pb1-xSmx[Zr0.50Ti0.45(Mo1/3In2/3)0.05]1-x/4O3, known as PSZT-PMI, were successfully synthesized using the mixed oxide method at high temperature. The concentrations of Sm+3 varied (x = 0.03, 0.08, 0.10, and 0.12). The resulting ceramic samples underwent sintering at 1250°C, followed by comprehensive analysis utilizing various laboratory techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), density measurement, dielectric measurements, and Raman spectroscopy. The XRD analysis confirmed the crystallization of the ceramics in a tetragonal phase structure. Among the samples, the one with 8% Sm3+ exhibited the highest experimental density, measuring 92.6641%. Remarkably, this particular ceramic sample also demonstrated exceptional dielectric properties, characterized by a relative permittivity (εr) of 12503.59, a loss tangent (tanδ) of 0.04168, and a Curie temperature (Tc) of 635K. SEM micrographs revealed the presence of uniformly distributed grains with varying shapes and sizes across the entire surface of the samples. [ABSTRACT FROM AUTHOR]

This study investigates the effect of positive temperature coefficient (PTC) fillers, i.e., barium strontium titanate (BST‐60) and nano hexagonal boron nitride (h‐BN) fillers, on thermal and dielectric insulation properties of epoxy (EP). The electrical resistivity, DC breakdown strength, space charge, thermal conductivity, thermogravimetric analysis, and glass transition temperature (Tg) of EP composites were measured. Results indicate that, below curie temperature, the EP composites containing 0.5 and 1 wt% of BST and 5 wt% of h‐BN have superior electrical resistivity, breakdown strength, and thermal conductivity. However, above curie temperature, the EP composites containing 2 and 2.5 wt% of BST and 5 wt% of h‐BN have superior insulation properties than the pure EP and other composites. While the thermal properties of EP improve with an increase in h‐BN loading to 10 wt%, its dielectric properties are slightly compromised due to the presence of tiny defects in the composite material. It is hypothesized that the BST‐60 suppresses the negative temperature coefficient effect (NTC) of EP by regulating the electrical resistivity above the curie point, whereas nano h‐BN enhances the thermal conductivity of EP by constructing a heat dissipation path. The proposed mechanism for charge dynamics along with heat conduction‐dissipation explains the fillers' behavior at different temperatures. Highlights: Analysis of epoxy composites with polydopamine‐modified BST and h‐BN fillers.PTC fillers are used to mitigate the negative temperature effect of epoxy.Optimal fillers wt% improves dielectric and thermal properties.This study shows that optimized epoxy composites can be used for packaging. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for the fabrication of magnetoelectric composites aimed at enhancing cross-coupling between electrical and magnetic phases for potential applications in intelligent sensors and electronic components. Unlike previous methodologies known for their complexity and expense, our method offers a simple and cost-effective assembly process conducted at room temperature, preserving the original properties of the components and avoiding undesired phases. The composites, composed of PZT fibers, cobalt (CoFe2O4), and a polymeric resin, demonstrate the uniform distribution of PZT-5A fibers within the cobalt matrix, as demonstrated by scanning electron microscopy. Detailed morphological analyses reveal the interface characteristics crucial for determining overall performance. Dielectric measurements indicate stable behaviors, particularly when PZT-5A fibers are properly poled, showcasing potential applications in sensors or medical devices. Furthermore, H-dependence studies illustrate strong magnetoelectric interactions, suggesting promising avenues for enhancing coupling efficiency. Overall, this study lays the basic work for future optimization of composite composition and exploration of its long-term stability, offering valuable insights into the potential applications of magnetoelectric composites in various technological domains. [ABSTRACT FROM AUTHOR]

The purpose of this article is to determine the dielectric characteristics of wood species from Central African forests at microwave frequency for use as patch antenna substrate. The measurements were carried out on dried wood at frequencies of 930 MHz and 2.48 GHz. The suitability of the wood as a printed microwave antenna substrate will be determined by the values taken by the complex parameters "permittivity" ε′, loss tangent "tanδ," and "permeability" μ = 1. The measurement method chosen in this work is the method of small disturbances in a cylindrical cavity operating in the TM010 mode. The values obtained for each species confirm the anisotropic nature of the wood. These measurements will also confirm that losses, which are the main criterion for selecting wood as substrate, increase with the wood species category and its density. The design and simulation results at 28 GHz of a travelling wave antenna on a wood substrate show that antennas can radiate with these materials in the millimetre band. [ABSTRACT FROM AUTHOR]

Dielectric elastomers, such as thermoplastic polyurethanes (TPUs), are widely used as the dielectric layer, encapsulation layer, and substrate of flexible and stretchable devices. To construct capacitors and actuators that work stably upon deformation, it has become urgent to investigate the evolution of dielectricity under stress and strain. However, the lack of effective methods for estimating the dielectric constant of elastomers under strain poses a big challenge. This study reports a device for the in situ measurement of the dielectric constant of TPU under strain. It is found that upon stretching TPU to a strain of 400%, its dielectric constant decreases from 8.02 ± 0.01 to 2.88 ± 0.25 (at 1 MHz). In addition, combined Fourier-transform infrared spectroscopy, the X-ray scattering technique, and atomic force microscopy were utilized to characterize the evolution of the microstructure under strain. The investigation under tensile strain reveals a decreased density and average size of polarized hard domains, along with a tendency of the molecular chains to align in parallel with the tensile stress. The evolution of the microstructures results in a reduction in the measured dielectric constant in TPU. [ABSTRACT FROM AUTHOR]

We report high-resolution calorimetric, optical and dielectric studies on two Schiff's based liquid crystalline materials, 4O.5 and 5O.5, which exhibit multiple phase transitions. The study goes beyond the commonly studied isotropic-to-nematic (I–N) and nematic-to-smectic A (N–SmA) phase transitions and explores higher-order smectic phase transitions. The critical exponent, α values, for different phase transitions has been explored. For the I–N, N–SmA, SmA–SmC, SmC–SmF, SmF–CrG and SmB–CrG transitions, α values close to 0.5 and amplitude ratios A−/A+ ~ 1.6 and D−/D+ ~ 1 indicate a first-order nature. Notably, for the SmA–SmB transition, although α (≈ 0.64) is larger than the tricritical value of 0.5, A−/A+ ~ 1.2 and D−/D+ ~ 1, and the study reports an order parameter critical exponent (β) of 0.26 ± 0.002, which supports a tricritical nature for this transition. Importantly, the ratios of A−/A+ and D−/D+ are found to have similar values across all three-measurement methods, indicating consistency and agreement among these methods. [ABSTRACT FROM AUTHOR]

We study the effects of concentration and size of the doped silver nanoparticles on material properties of 6CB nematic: 4-hexyl-4'-cyanobiphenyl using electrical, dielectric measurements along with the polarising microscopy methods. We show that the dispersed NPs do not affect the nematic-isotropic liquid transition temperature. We report that the doped NPs decrease the dielectric anisotropy, elasticity and viscosity of the material. We attribute this behaviour to the fact that the dispersed NPs lower the orientational order parameter of the nematic. However, the threshold voltage stays almost unaffected by the doped NPs and the switching-off time is decreased only at certain NPs concentration. Using our measured data, we test the validity of the predicted by the classical Maier-Saupe theory, linear dependence of the elasticity vs the square root of the order parameter. We show that while for the pure sample the mentioned dependence follows the classical prediction, the dispersed samples elasticity shows anomalous behaviour. We report that the mentioned dependence predicted by Gelbart-Ben Shaul theory fits well with the doped samples measured data. [ABSTRACT FROM AUTHOR]

The spontaneous polarization of perovskite layer structured Sr2Nb2O7 ferroelectrics (FEs) is originated from mainly the oxygen octahedral rotations and partially the displacement of Sr2+ ions. However, there is FE anomaly of showing the typical characteristics of antiferroelectric (AFE)‐like behavior with double polarization–electric field hysteresis loops of Sr2Nb2O7 ceramics by Pb doping. Here, combinations of low frequency and sub‐terahertz band dielectric measurements under applied DC field reveal field‐induced transition from AFE to FE structure. Temperature dependence of dielectric constant suggested a second‐order phase transition near 215°C, which further supported by the lattice parameters and thermal expansion coefficient extracted from the variable temperature X‐ray diffraction in the heating and cooling processes. The selected area electron diffraction results show no new superlattice spots are observed along [1 0 0] zone axis related to c direction. We proposed a model based on octahedral tilting/rotation that accounted for the incommensurate lattice modulation in the c direction for Sr2Nb2O7 system by Pb doping. All the results show AFE‐like behavior be likely to origin from the electron structures of Pb2+ with a 6s2 lone pair. Our results gave us a new concept provide possibilities for the design of AFE‐like materials in layer structured compounds with super high FE Curie point. [ABSTRACT FROM AUTHOR]

Infrared Reflection Absorption Spectroscopy (IRAS) on dielectric single crystals is challenging because the optimal incidence angles for light–adsorbate interaction coincide with regions of low IR reflectivity. Here, we introduce an optimized IRAS setup that maximizes the signal-to-noise ratio for non-metals. This is achieved by maximizing light throughput and by selecting optimal incidence angles that directly impact the peak heights in the spectra. The setup uses a commercial Fourier transform infrared spectrometer and is usable in ultra-high vacuum (UHV). Specifically, the optical design features sample illumination and collection mirrors with a high numerical aperture inside the UHV system and adjustable apertures to select the incidence angle range on the sample. This is important for p-polarized measurements on dielectrics because the peaks in the spectra reverse the direction at the Brewster angle (band inversion). The system components are connected precisely via a single flange, ensuring long-term stability. We studied the signal-to-noise ratio (SNR) variation in p-polarized IRAS spectra for one monolayer of CO on TiO2(110) as a function of incidence angle range, where a maximum SNR of 70 was achieved at 4 cm−1 resolution in a measurement time of 5 min. The capabilities for s polarization are demonstrated by measuring one monolayer D2O adsorbed on a TiO2(110) surface, where a SNR of 65 was achieved at a peak height ΔR/R0 of 1.4 × 10−4 in 20 min. [ABSTRACT FROM AUTHOR]

The polycrystalline (1-x)BiFeO3-xNa0.5Bi0.5TiO3, x = 0.00, 0.05, 0.10 and 0.15, ceramics were prepared using conventional solid-state route. The structural studies using X-ray diffraction and Raman measurements confirmed the rhombohedral R3c structure of the compounds. The scanning electron micrographs showed that grain size decreased, and the density of the compounds increased with the higher Na0.5Bi0.5TiO3 content. The weak ferromagnetism was induced in the solid solution of antiferromagnetic BiFeO3 compound with Na0.5Bi0.5TiO3 content. The structural distortions were increased with the increase of x, which favours the increase of weak ferromagnetism in the antiferromagnetic compound. The electric polarisation measurements indicated that leakage character decreased with the increase in Na0.5Bi0.5TiO3 fraction. The temperature and frequency-dependent dielectric measurements showed that the dielectric constant was improved and loss tangent was decreased in Na0.5Bi0.5TiO3 rich compounds. The temperature dependence of dielectric constant data showed a dielectric anomaly near the magnetic transition of BiFeO3, which shifted towards the lower temperature side with the increase of x. The UV-VIS-NIR spectroscopy measurements evidenced an increase in band gap energy for higher Na0.5Bi0.5TiO3 concentration.. [ABSTRACT FROM AUTHOR]

As a simple, fast, and non-destructive measuring technology, dielectric spectroscopy is usually used to analyze the dielectric properties of agricultural products and food, and then to predict the main components of materials. However, the large and expensive vector network analyzers (VNA) with expensive analysis software applied in measuring dielectric properties make research limited to the laboratory. To acquire dielectric spectra in situ, a model for solving relative complex permittivity was derived, and its performance was validated. Then, a low-cost portable dielectric spectrometer with a mini VNA, a Raspberry Pi, and a coaxial probe as core parts was developed over the frequency range of 100-3000 MHz. The stability and accuracy of the developed spectrometer were tested using milk and juice. The results indicated that the relative errors of the model were within ±5% for dielectric constant (s') and loss factor (e"). The coefficients of variation of measured e' and e" by the developed spectrometer at 100-3000 MHz were less than 1% and 2%, respectively. Compared with the dielectric properties obtained by using a commercial dielectric measurement system, the relative errors of measured e' and e" were within ±3.4% and ±6.0%, respectively. This study makes fast, non-destructive, and on-site food quality detection using dielectric spectra possible. [ABSTRACT FROM AUTHOR]

To investigate the effect of the stability of oxygen vacancies on the low-temperature degradation (LTD) resistance of two kinds of commercial zirconia-based materials (3Y-TZP ceramics and Ce-TZP/Al 2 O 3 composites) via the dielectric probing methods. The commercial 3Y-TZP ceramics and Ce-TZP/Al 2 O 3 composites were prepared via conventional solid-state methods. Density, phase content, microstructure, strain, and biaxial flexural strength (BFS) of two materials were investigated using Archimedes method, XRD, SEM, strain-electric field (S-E) loops and ball-on-ring methods, respectively. The concentration of oxygen vacancies before and after LTD of two materials were evaluated using dielectric probing and XPS methods. The XRD analysis revealed that compared to the 3Y-TZP ceramics, the Ce-TZP/Al 2 O 3 composites showed better LTD resistance, without clear LTD. The greater LTD resistance for Ce-TZP/Al 2 O 3 composites was associated with their stability of oxygen vacancies, by higher activation energy based on the dielectric measurements and XPS results. For the 3Y-TZP ceramics that underwent the tetragonal to the monoclinic phase transition during the LTD treatment, the concentration of their oxygen vacancies decreased after LTD. In addition, the Ce-TZP/Al 2 O 3 composites exhibited higher flexural strength and potential fracture toughness based on the BFS testing and strain vs electric field measurement results, indicating a great potential for use in fixed restorative dental applications. This work suggested the stability of oxygen vacancies played a key role in the resistance to LTD. Optimizing the stability of the oxygen vacancies is key to the development of more reliable zirconia- based dental biomaterials with greater resistance to LTD. • LTD observed in the 3Y-TZP ceramics, accompanied with their decrease concentration of oxygen vacancies. • The stability of oxygen vacancies in the Ce-TZP/Al 2 O 3 composites played an important role in their resistance to LTD. • Dielectric probing was proved to be a useful method to investigate the LTD of zirconia bio-ceramics. [ABSTRACT FROM AUTHOR]

The quality 2-amino-5-chloropyridinium 4-aminobenzoate (2A5ClP4AB) single crystals were grown in methanol solvent by employing the solvent evaporation technique. The stoichiometry ratio of 2A5ClP4AB was confirmed by microanalysis. The melting point, decomposition, crystalline phase, purity, and specific heat capacity of 2A5ClP4AB crystal were explored by thermogravimetric-differential thermal analyses (TG–DTA), differential scanning calorimetry (DSC), and modulated scanning calorimetry (MDSC) methods. The various dielectric properties of 2A5ClP4AB single crystal concerning temperature and frequency were examined by dielectric measurements. The nonlinear optical (NLO) parameters such as dipole moment, polarizability, first-order hyperpolarizability, and second-order hyperpolarizabilities of the 2A5ClP4AB molecule were computed using density functional theory (DFT) by utilizing the Gaussian 09 program. The figured HOMO–LUMO energies of 2A5ClP4AB demonstrate the occurrence of a charge transfer mechanism, whereas the MESP map illustrates how various molecular interactions took place in it. Hirshfeld surface analyses helped to decode the nature of the interactions and packing structure of the crystals. The above studies were intended to explore the structural, thermal, electrical and NLO properties of 2A5ClP4AB and also to strengthen its effectiveness for optoelectronic and frequency conversion applications. [ABSTRACT FROM AUTHOR]

This work proposes the synthesis of strontium ferrite by two different methods: sol-gel (SG), using powdered coconut water (PCW) as a precursor, and laser floating zone (LFZ). The SG samples were after treated at temperatures of 700, 1000, and 1200 °C, while the samples obtained by LFZ were grown at pulling rates of 10, 50, and 100 mm/h. All samples studied were subjected to structural characterization techniques, as well as electrical (AC and DC) and magnetic characterization. Through X-ray diffraction, it was possible to observe that all the samples presented strontium ferrites, but none were single phase. The phases detected in XRD were confirmed by Raman spectroscopy. Scanning electron micrography allowed the observation of an increase in grain size with the temperature of SG samples and the reduction of the porosity with the decrease in growth rate for LFZ fibers. Through electrical analysis, it was observed that the most suitable samples for energy storage were the samples grown at 100 mm/h ( ε r ′ = 430,712; ε r ″ = 11,577; tan δ = 0.84; σac = 0.0006 S/m, at 1 kHz). The remaining samples had high dielectric losses and can be applied in electromagnetic shielding. The SG 700 °C sample presented the highest magnetization (38.5 emu/g at T = 5 K). [ABSTRACT FROM AUTHOR]

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The authors of numerous measurements of conductivity for suspensions of nanoparticles of various types carried out in the last decade came to the general conclusion that the well-known Maxwell's theory is not applicable to quantitative explanation of the properties of such systems. In the present work, we demonstrate that the Maxwell's theory can be still applicable even for such systems, but the specifics of the standard ac measurements have to be correctly taken into account. Namely, the dependence of the capacitance of "metal–electrolyte" cuvette boundaries on nanoparticle adsorption, which in its turn dramatically depends on nanoparticle concentration, has to be taken into account. The latter circumstance strongly (via the R C characteristic of the circuit) affects the results of conductivity measurements. We propose the new algorithm of the impedance measurement data analysis for the particles' concentration dependence of conductivity σ (ϕ) (where ϕ is the volume fraction of nanoparticles in suspension) for the suspensions of the diamante nanoparticles in alcohol which demonstrates the adequate correspondence of the Maxwell's theory to the available experimental findings. [ABSTRACT FROM AUTHOR]

Nonlinear dielectric measurements are an important tool to access material properties and dynamics concealed in their linear counterparts, but the available data are often intermittent and, on occasion, even contradictory. Employing and refining a recently developed technique for high ac field dielectric measurements in the static limit, we ascertain nonlinear effects in glycerol over a wide temperature range from 230 to 320 K. We find that the temperature dependence of the Piekara factor a, which quantifies the saturation effect, changes drastically around 290 K, from ∂a/∂T = +1.4 to −130 in units of 10−18 V2 m−2 K−1. These high values of |a| quantify not only elevated dielectric saturation effects but also indicate a temperature driven increase in higher-order orientational correlations and considerable correction terms with respect to the central limit theorem. No signature of this feature can be found in the corresponding low field data. [ABSTRACT FROM AUTHOR]

The capability of dielectric measurements was significantly increased with the development of capacitive one-side access physical sensors. Complete samples give no opportunity to study electric susceptibility at a partial coverage of the one-side access sensor's active area; therefore, partial samples are proposed. The electric susceptibility at the partial coverage of a circular one-side access sensor with cylinders and shells is investigated for polyurethane materials. The implementation of the relative partial susceptibility permitted us to transform the calculated susceptibility data to a common scale of 0.0–1.0 and to outline the main trends for PU materials. The partial susceptibility, relative partial susceptibility, and change rate of relative partial susceptibility exhibited dependence on the coverage coefficient of the sensor's active area. The overall character of the curves for the change rate of the relative partial susceptibility, characterised by slopes of lines and the ratio of the change rate in the centre and near the gap, corresponds with the character of the surface charge density distribution curves, calculated from mathematical models. The elaborated methods may be useful in the design and optimization of capacitive OSA sensors of other configurations of electrodes, independent of the particular technical solution. [ABSTRACT FROM AUTHOR]

This article explores the measurement of electric fields in parallel plate capacitors. It explains the concept of parallel plate capacitors and their applications in experiments related to electric charges. The article acknowledges that real-life capacitors do not meet ideal conditions and presents standard formulas for ideal capacitors. It also discusses a simple experiment using a charged bead to measure the electric field inside and outside a parallel plate capacitor, along with the theoretical framework and equations involved. The authors conducted experiments to measure the electric field in both regions and discovered the presence of a field outside the capacitor due to the fringing effect. The study provides a theoretical explanation and a practical apparatus for measuring the electric field of a parallel plate capacitor. The article was authored by Taehun Jang, Hyejin Ha, Sang Ho Sohn, and Jungmin Moon, with Sang Ho Sohn being a professor of physics at Kyungpook National University in South Korea. [Extracted from the article]

Epoxy nano-magnetic composites exhibit remarkable and promising properties by synergistically combining the properties of epoxy resin and magnetic nanofillers. The current study deals with the synthesis of Fe3O4, NiFe2O4, and CoFe2O4 nanoparticles and their respective nanoparticles-doped epoxy composites, as well as the structural, optical, and dielectric characterization of the resultant nano-composites. To investigate the surface morphology of the synthesized nanoparticles, field emission electron microscopy (FESEM) analysis was employed. By measuring electron diffraction spectroscopy (EDS), the presence of various chemicals was verified. X-ray diffraction (XRD) was used to determine the structural details of the synthesized nanoparticles and nanoparticles-doped epoxy composites. The structural chemistry and surface functionality of the nano-epoxy composites were investigated using Fourier transform infrared spectroscopy (FTIR). The magnetic properties of the synthesized nanoparticles and nanoparticles loaded epoxy composites were also studied using a vibrating sample magnetometer (VSM). UV–visible reflection spectroscopy was also carried out to find the optical properties of the synthesized nanoparticles, neat (undoped) epoxy, and nanoparticles-doped epoxy composites. Dielectric spectroscopy measurements of nanoparticles-doped epoxy composites were performed using an Agilent E4980A precision LCR (Inductance Capacitance Resistance) meter with an Agilent 16451B-test fixture LCR and vector network analyzer (VNA) in the frequency span of 10 kHz to 2 MHz and 200 MHz to 20 GHz, respectively. The influence of the synthesized nanoparticles on the neat (undoped) epoxy composites and the results in view of future applications are fully discussed. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites (PNCs), exhibiting enhanced physical properties, are emerging as innovative functional materials due to their versatile characteristics suitable for various technological applications. Composite films comprising 0.1% copper (Cu) doped Nickel oxide (NiO) [CNO1 (350)] nanoflakes calcined at 350 °C embedded in Poly (vinylidene fluoride) (PVDF) polymer were prepared using the solution casting method. The influence of CNO1 (350) filler incorporation on the structure and morphology of the composite films was scrutinized through X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM). Results unveiled a direct correlation between CNO1 (350) filler concentration and the crystallinity, β-phase content, and morphology of the composite films, attributed to heterogeneous nucleation. Room temperature electrical measurements indicated dielectric constants reaching more than six times at 40 Hz and a conductivity increase exceeding two orders of magnitude, with a percolation threshold identified around 25wt% of CNO1 (350) filler content. The observed outcomes are elucidated through Maxwell–Wagner–Sillars interfacial polarization occurring at the interface of CNO1 (350) and the insulating polymer matrix. This elucidation involves the development of a conductive network and the establishment of a micro-capacitive structure within the PVDF thin films modified with CNO1 (350). [ABSTRACT FROM AUTHOR]

Magnesium titanate ceramics were prepared by reactive spark plasma sintering (SPS) at 1200 °C for 5 min. Prior to sintering, MgO and TiO 2 powders were mixed by high energy ball milling (HEBM) for 15, 30, or 60 min. The effect of milling time on phase composition was analyzed by X-ray diffraction (XRD) for milled powders and sintered specimens. The morphology of the sintered ceramics was investigated by scanning electron microscopy (SEM), while elemental distribution was determined by energy dispersive spectroscopy (EDS). The presence of the MgTi 2 O 5 phase was detected in XRD and was confirmed by EDS analysis. Microcracking was observed for specimens prepared with longer milling times and attributed to the coefficient of thermal expansion (CTE) mismatch dominantly due to the anisotropic crystal structure of MgTiO 3 phase. The sample milled for 15 min showed the highest Vickers hardness due to less or no microcracking and nearly full density. The dielectric measurements in the range of 10 Hz–250 MHz demonstrated extremely high dielectric permittivity, as high as 104 at 1 kHz. An increase in loss tangents was observed due to oxygen vacancy formation, which was promoted by the vacuum environment during SPS. Oxygen vacancy-related dielectric relaxation was also detected and explained. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Bi0.8Ba0.1Er0.1Fe0.96Cr0.02Mn0.02O3 (BBEFCMO) multiferroic ceramic was synthesized through the sol-gel route. The impact of incorporating various dopants into both A and B sites of the BiFeO3 was investigated, and structural, Raman, dielectric, electric, and magnetic properties were studied. X-ray diffraction analysis and Raman spectroscopy revealed a rhombohedral structure with the R3c space group for the doped material (BBEFCMO). Dielectric properties were examined across a frequency range of 102–106 Hz. The present multiferroic material exhibits a colossal dielectric constant and minimal dielectric loss tangent, making it suitable for applications in energy storage. Furthermore, the Cole-Cole type of relaxation was deduced from the imaginary part of the modulus for both grain and boundary-grain contributions. Overall, this study indicates that substituting ions in both A and B sites of BiFeO3 significantly enhances its multiferroic properties, as evidenced by dielectric and magnetic measurements. [ABSTRACT FROM AUTHOR]

Accurate estimation of soil water content (SWC) is crucial for effective irrigation management and maximizing crop yields. Although dielectric property-based SWC measurements are widely used, their accuracy is still affected by soil variability, soil–sensor contact, and other factors, making the development of convenient and accurate soil-specific calibration methods a major challenge. This study aims to propose a plate compression filling technique for soil-specific calibrations and to monitor the extent of soil biomass degradation using dielectric properties. Before and after biodegradation, dielectric measurements of quartz sand and silt loam were made at seven different water contents with three different filling techniques. A third-order polynomial fitting equation explaining the dependence of the dielectric constant on the volumetric water content was obtained using the least-squares method. The suggested plate compression filling method has a maximum mean bias error (MBE) of less than 0.5%, according to experimental results. Depending on the water content, silt loam's dielectric characteristics change significantly before and after biodegradation. The best water content, measured in gravimetric units, to encourage the decomposition of biomass was discovered to be 24%. It has been demonstrated that the plate compression filling method serves as a simple, convenient, and accurate alternative to the uniform compaction method, while the dielectric method is a reliable indicator for evaluating biomass degradation. This exploration provides valuable insights into the complex relationship between SWC, biomass degradation, and soil dielectric properties. [ABSTRACT FROM AUTHOR]

Electrocaloric effect and loss-induced self-heating are simultaneously investigated in single-crystalline relaxor 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 by a direct, high-resolution method. Transients of the total temperature change for few-cycle electric field pulses allow to distinguish and individually determine the contributions from electrocaloric effect and self-heating with millikelvin temperature and submillisecond temporal resolution. Simultaneous dielectric measurements make the comparison of observed self-heating to hysteresis losses possible, where very good agreement is found. The loss factor as a figure of merit for electrocaloric materials is directly obtained from the combined determination of caloric temperature change and losses. [ABSTRACT FROM AUTHOR]

The composite of zinc tungstate (ZnWO 4) and multi-walled carbon nanotubes (MWCNTs) demonstrated remarkable performance in supercapacitors and lithium-ion batteries. In this study, novel polymeric nanocomposites (PVP/CMC/MWCNTs/x wt.% ZnWO 4) were synthesized using solution casting and hydrothermal techniques. The resulting blends and filler ZnWO 4 were thoroughly characterized using X-ray diffraction and transmission electron microscopy techniques. Utilizing diffuse reflectance measurements, various optical parameters were analyzed. Upon the introduction of MWCNTs/ZnWO 4 into the PVP/CMC blend, its transmittance in the visible range experienced a reduction from ∼90 % to (15–30 %), while the reflectivity and absorptivity increased. The direct and indirect optical band gaps of PVP/CMC blend changed nonmonotonically upon loading with MWCNTs and ZnWO 4. The linear and nonlinear optical parameters were enhanced. Also, the fluorescence (FL) intensity exhibited a decline, and analysis of CIE chromaticity indicated that the blends are emitting blue light to different extents and the purity of the blend decreased from 71 % to 60 % when loaded with MWCNTs and 2.5 wt% ZnWO 4. From the dielectric measurements, the AC conductivity exhibited an increase, while the energy density experienced a reduction upon the incorporation of ZnWO 4. In general, the optical and dielectric characteristics of the current blends render them suitable for implementation in optoelectronic and energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, the effect of Sm ionic doping in BaTiO 3 for electrocaloric effect has been studied. Ba 1-x Sm x TiO 3 (x = 0, 0.02, 0.04, 0.06) ceramics were made via sol-gel method. All samples, according to XRD analysis, have a tetragonal symmetry that decreases with increasing Sm concentration. SEM micrographs revealed that, with the exception of the pure BaTiO 3 , all samples exhibited a dense microstructure. Compared to pure BaTiO 3 , thermal analysis using DSC measurement showed that as samarium content increases, the phase transition temperature decreases and the endothermic peak flattens. Dielectric measurements showed that the value of the loss tangent decreased and the value of the dielectric constant increased as the samarium doping concentration increased. Ferroelectric experiments highlighted that all samples were in the ferroelectric phase at room temperature. The remnant polarization increased with increasing Sm concentration. For Sm-doped ceramics the maximum value was Pr = 5.2 μC/cm2 for x = 6 %, under a maximum applied field of 25 kV/cm. An original customized pASC calorimeter was used in a direct method to study isothermal heat production resulting from the electrocaloric effect (ECE). According to the ECE results, the partial substitution of barium by samarium lowers the Curie temperature, which in turn lowers the temperature at which the electrocaloric effect is strongest. This extends the temperature range at which ECE can be used. For the sample Ba 0.96 Sm 0.04 TiO 3 , the maximum electrocaloric effect recorded is reached with a ΔT/ΔE = 0.343 K m/MV. [ABSTRACT FROM AUTHOR]