Permittivity Values Research Articles

Fabrication of Cellulose Powder Dielectric Composite Material using Pineapple Leaves Fiber

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

Investigating the microwave properties of carbon materials from microwave-driven methane pyrolysis

Rising carbon dioxide emissions due to fossil fuel combustion has led to the urgent need to investigate and adopt different energy solutions that can mitigate this problem. Hydrogen has surfaced as a promising alternative in the pursuit for CO2-neutral energy systems. Microwave pyrolysis of methane has recently emerged as an innovative method to accomplish this goal. To enhance our understanding of this technique and its scalability, it is essential to explore the microwave characteristics of the carbon used and generated during this process. This work investigates the microwave properties of two carbon samples (seed carbon; SC and product carbon; PC) from microwave-driven pyrolysis of methane. The cavity perturbation technique was employed from room temperature to 1250 °C for frequencies of 397, 912, 1429, 1948 and 2467 MHz. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis were also performed to elucidate the permittivity results. It was found that SC initially showed a decline in permittivity values up to 200 °C which is attributed to the release of moisture from the sample. These results were correlated to TGA/DSC which showed 5 % mass loss from 100 to 155 °C. The permittivity gradually reached a peak after which it started to fall due to high conductivity. In the case of the PC, the permittivities exhibited undulations but the values remained consistent. Since this form of carbon is formed at elevated temperature, no loss in moisture was seen in TGA/DSC. These findings indicate that the microwaves can penetrate and heat both the samples uniformly across their entire volume, resulting in efficient heating. SC demonstrated higher permittivity magnitudes compared to PC, suggesting its better responsiveness to microwave fields. Nonetheless, the possibility of thermal runaway in SC renders it less favorable for applications involving microwave-driven pyrolysis. XRD analysis showed that the samples SC and PC demonstrated amorphous carbon structures, with PC showing indications of graphitization to some extent. Both SC and PC have the potential to serve as microwave heat carriers in the methane pyrolysis process. This suggests that utilizing the carbon produced can enable a self-sufficient process, eliminating the necessity for costly catalysts.

Influence of Nano-CeO2 and Graphene Nanoplatelets on the Conductivity and Dielectric Properties of Poly(vinylidene fluoride) Nanocomposite Films.

Novel three-phase polymer nanocomposites (PNCs) based on cerium oxide (CeO2) nanoparticles (NPs) and graphene nanoplatelets (GNPs) incorporated in a poly(vinylidene fluoride) (PVDF) matrix were formulated using a solution-casting approach. To understand the structural and morphological features of PVDF/CeO2/GNP nanocomposites (NCs), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses were accomplished. The PVDF/CeO2/GNP NCs displayed improved thermal stability which resulted from strong bonding between GNPs and CeO2 NPs and restriction of the polymer chain movement. The introduction of CeO2 NPs and GNPs within the PVDF matrix and good synergy between CeO2 NPs and GNPs led to variable mechanical properties of the prepared NCs. The PVDF/CeO2/GNP NCs portrayed reduced thermal stability, which could be due to the increased mobility of PVDF chains imposed by GNPs leading to the formation of volatile degradation products. Moreover, PVDF/CeO2/GNP NCs exhibited good electrical conductivity and high dielectric permittivity. The obtained dielectric permittivity value for the PVDF/CeO2/GNP NCs was 3-fold greater than PVDF/CeO2 NCs, making these novel tertiary composite materials a probable candidate for energy-storage applications.

Spinel-trirutile microwave dielectric ceramics with high Q and excellent temperature stability based on MgO-Al2O3-Ta2O5 ternary systems

(1-x)MgAl2O4-xMgTa2O6 composite ceramics based on the MgO-Al2O3-Ta2O5 pseudoternary phase diagram were prepared by the solid-state reaction. MgAl2O4 and MgTa2O6 could coexist due to their different crystal structures. MgAl2O4 inhibited the rapid growth of MgTa2O6 grains, and dense microstructures (ρ > 95%) with a uniform grain size distribution was obtained, with an optimal densification temperature of 1550 - 1575 °C. The temperature coefficient of resonant frequency (τf) and quality factor (Q×f) were optimized by introducing MgTa2O6 phases with low dielectric loss and positive τf. In addition, the partial solid solutions of Al3+ into Ta5+ sites resulted in loosening bonds within [Al/TaO6] octahedra and abnormally large polarizabilities, which was confirmed by the decrease in VTa-O and the redshift of A1 g(Ta-O) mode. Consequently, the relative permittivity (εr) and τf values of MgAl2O4-MgTa2O6 composite ceramics were further enhanced, exceeding the predicted ones. The 0.6MgAl2O4-0.4MgTa2O6 composition sintered at 1550 °C achieved excellent performance, with a near-zero τf value of 3.3 ± 1.7 ppm/°C, a low εr of 16.4 ± 0.3 and an ultra-high Q×f of 179,000 ± 6700 GHz @ 8.94 ± 0.04 GHz. These findings hold promising applications in the field of 5 G/6 G high-frequency communication.

Exciton interactions of chlorophyll tetramer in water-soluble chlorophyll-binding protein BoWSCP

The exciton interaction of four chlorophyll a (Chl a) molecules in a symmetrical tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP was analyzed in the pH range of 3–11. Exciton splitting ΔE = 232 ± 2 cm−1 of the Qy band of Chl a into two subcomponents with relative intensities of 78.1 ± 0.7 % and 21.9 ± 0.7 % was determined by a joint decomposition of the absorption and circular dichroism spectra into Gaussian functions. The exciton coupling parameters were calculated based on the BoWSCP atomic structure in three approximations: the point dipole model, the distributed atomic monopoles, and direct ab initio calculations in the TDDFT/PCM approximation. The Coulomb interactions of monomers were calculated within the continuum model using three values of optical permittivity. The models based on the properties of free Chl a in solution suffer from significant errors both in estimating the absolute value of the exciton interaction and in the relative intensity of exciton transitions. Calculations within the TDDFT/PCM approximation reproduce the experimentally determined parameters of the exciton splitting and the relative intensities of the exciton bands. The following factors of pigment-protein and pigment–pigment interactions were examined: deviation of the macrocycle geometry from the planar conformation of free Chl; the formation of hydrogen bonds between the macrocycle and water molecules; the overlap of wave functions of monomers at close distances. The most significant factor is the geometrical deformation of the porphyrin macrocycle, which leads to an increase in the dipole moment of Chl monomer from 5.5 to 6.9 D and to a rotation of the dipole moment by 15° towards the cyclopentane ring. The contributions of resonant charge-transfer states to the wave functions of the Chl dimer were determined and the transition dipole moments of the symmetric and antisymmetric charge-transfer states were estimated.

Structural studies, dielectric and electrical properties of (1-x) Pb(Zr0.52Ti0.48)O3– xCoFe2O4 multiferroics materials

This work aimed to develop a better combination of PbZr0.52Ti0.48O3 (PZT) and CoFe2O4 (CFO) ceramics with enhanced structural, dielectric, and electric properties. For this aim, (1-x)PZT-xCFO nanocomposites at (0.00, 0.10, 0.20, 0.30, 0.40, 0.50, and 1.00) were synthesized using the combination before calcination of sol–gel (for PZT ceramic) and solid-state (for CFO material) methods. The powder X-ray diffraction analysis reveals that the CFO crystallizes in a spinel cubic structure with the Fd3m space group structure, while the PZT compound crystallizes in two tetragonal and rhombohedral structures with P4mm and R3m space groups respectively, which is confirmed by Raman spectra which also demonstrate that CFO content in (1-x)PZT-xCFO composites affects the vibration types. The scanning electron micrographs (SEM) show that the grains are homogeneous and irregular, with several pores on the surface of ceramics. The dielectric properties of the ceramics were investigated as a function of temperature (from 25 to 500 °C) and frequency (from 100 Hz to 2 MHz) using complex impedance spectroscopy. It shows that with the increase of CFO ratio, the dielectric permittivity values increase in the composites until the composition corresponding to x = 0.3 From 485 to 1620 at 5KHz) and then decreases until 65 for x = 1.00. The dielectric constant a function of frequency at different temperatures of (1-x)CFO-xPZT composites indicated that the dielectric constant increases with the increase of CFO content. The impedance spectrum is characterized by simple semicircular arcs and shows a non-Debye relaxation. The electric conductivity reveals that as CFO increases, conductivity remains constant, and the frequency dependence of conductivity shifts away from high frequencies. Also, the value of the exponent n decreases from 1.44 to 0.26 with an increasing CFO concentration. The activation energy is between 0.32 and 0.16 which confirms that electron hopping is responsible for electrical conduction.

DUAL-BAND BANDSTOP FILTERS BASED ON ULTRA THIN FREQUENCY SELECTIVE SURFACES

In this paper, we present designs for terahertz filters with two independent stopbands based on periodic metallic resonant structures patterned on the dielectric substrate. Two simple and thin structures are proposed to realize required characteristics for single-polarized and dual polarized filter designs. To realize single polarized one, a unit cell of the proposed periodic structure consists of two sets rectangular shape conducting metal patches patterned on the top of the dielectric substrate, and the dual-band response is due the lattice resonances observed in the unit cell. To realize dual polarized filter design, a modified unit cell is considered with additional patches on the bottom of the dielectric substrate. The patches on the bottom layer are the same ones as on the top layer but orthogonally oriented. For this case, polarization-independent frequency response can be obtained after geometric optimization of the unit cell because the top and the bottom layers resonantly interact with only the TE or TM incident plane wave to minimize cross coupling effects between the layers. In order to intensively understand the transmission performance of the proposed filters, a large number of simulations using integral equation method are performed based on the different values for permittivity, period of the unit cell, dielectric thickness, and geometric dimensions. The electric field distributions are analyzed to understand the mechanism of the resonance behavior.

ELECTRON-BEAM SINTERING OF ZIRCONIUM DIOXIDE/TITANIUM CERAMICS FOR MICROELECTRONICS PRODUCTS

Zirconium dioxide (ZrO<sub>2</sub>) has excellent physical, chemical, and mechanical properties. These properties make it an excellent material for composite ceramics. High values of dielectric permittivity, mechanical resistance, and high radiation resistance allow it to be used to protect integrated circuits (ICs) from external influences. In this study, we fabricated ZrO<sub>2</sub>/titanium (Ti) ceramic composites by employing electron-beam sintering and a forevacuum-pressure plasma-cathode electron-beam source. We used a scanning electron microscopy method to study the properties of the ceramics after sintering. The results obtained showed that with an increase in the sintering temperature up to 1700°C, the Ti content in the near-surface layer of the composite decreased to almost 0. The depth of the region with low metal component content also increased with an increase in the sintering temperature and reached 2 mm in 3-mm-thick samples. This method can be used in the production of composite materials used in IC packaging.

Numerical modeling of metal-dielectric metasurface as an element of microwave sensors for biomedical applications

This paper reports the results of numerical modeling of wave reflection coefficient behavior of the metal-dielectric metasurface at microwaves that can be used for biomedical applications. The study includes optimization of the working parameters of the metasurface-based structure as a sensitive element of a microwave sensoring systems for determination of proteins concentration in different solutions. In the current research a unit with the geometry, which is similar to the geometry of one well of the standard 96-multiwell laboratory microplate, is used as a resonant metasurface unit cell and liquid-holding structure. Human serum albumin (HSA) is used as a protein specimen in our model study. The present numerical modeling is based on the results of our previous experimental measurements of complex permittivity values of HSA water solutions and its biochemical reaction mixtures using microwave dielectrometry method and the developed setup. The unit cell approach calculations are performed by COMSOL Multiphysics software. The optimization of working parameters of the metal-dielectric metasurface structure with tested solutions allow us to observe the resonance effects of the wave reflection coefficient in the microwave range. We can determine the HSA concentration changes in water solutions and enzymatic reaction mixtures by the resonance frequency shift of the wave reflection coefficient of the metal-dielectric metasurface. Developed metal-dielectric metasurface-based structure demonstrates prospects to be used as a sensitive element of microwave sensors for proteins concentration determination with biomedical purposes.

Synthesis and characterization of cellulose nanocrystal derived from paper as nanofiller for polymer insulation materials

The synthesis and characterization of cellulose nanocrystal by utilizing filter paper as the source of material deserves to be an advanced approach. Nanocellulose has received enormous attention due to its unique properties. Being the most abundant organic polymer on earth, nanocellulose is the most suitable candidate for alternative replacement of petroleum-based products. The cellulose was extracted from filter paper by chemical processes involved alkali treatment, bleaching treatment, and acid hydrolysis. Cellulose nanocrystal has been characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Electrical Impedance Spectroscopy (EIS). The dielectric permittivity of the prepared CNC have been investigated in the different temperatures. The nanofiller CNC exhibits a higher real permittivity value at elevated temperatures (60 °C) in the low-frequency region. At high-frequency region, the real permittivity is independent on temperature. In brief, the studies point to the application potential of CNC for future insulation materials.

Electromagnetic cloak design with mono-objective and bi-objective optimizers: seeking the best tradeoff between protection and invisibility

We revisit the design of cloaks, without resorting to any geometric transform. Cancellation techniques and anomalous resonances have been applied for this purpose. Instead of a deductive reasoning, we propose a novel mono-objective optimization algorithm, namely a ternary grey wolf algorithm, and we adapt a bi-objective optimization algorithm. Firstly, the proposed chaotic ternary grey wolf algorithm searches three-valued spaces for all permittivity values in the cloak while minimizing the summation of a protection criterion and an invisibility criterion. Secondly, a bi-objective genetic algorithm is adapted to find pairs of optimal values of invisibility and protection.

Wastewater leakage identification in WWTP and concrete pipelines using integrated geophysical imaging methods

Industry and mining activities covers a broad spectrum of processes that dispose an abundant amount of wastewater. Given the vast array of industries, there are equally large number of heavy metals, organic solvents, and hydrocarbons pollutants associated with its wastewater, posing a great threat to aquifers, especially groundwater. Main contributor of this polluting scheme are from the leakage of underground/surface storage tanks, effluent pipework, industrial sewers, and waste injection system. To ascertain the presence of pollution in the subsoil and groundwater resources, an integrated geophysical method can be the alternative of non-invasive methods. The presence of contaminants in subsoil alters the physical properties of rock formations and decrease pore-water resistance, therefore it can be mapped by geoelectrical resistivity. In this paper, study case was conducted in Medan Industrial Estate, Indonesia, to identify potential leakage under the Wastewater Treatment Plant (WWTP) and its pipework, using Geoelectrical Wenner and Magnetotelluric Method with 5 lines in the interval of 40-60 meters and Magnetotelluric Method throughout the 175 meters of pipework in the production area. Based on the Geoelectrical Method, an anomaly with a low resistivity value was detected within 7 meters of the ground depth. Meanwhile, in the Magnetotelluric Method, a moderate permittivity value was detected that is local and located within 2 meters depth which is where the pipe and the bottom of the WWTP storage tank is located. In conclusion, based on the results obtained from the Geoelectrical and Magnetotelluric Methods that have been carried out in the WWTP area and along the wastewater pipeline leading to the WWTP, no anomalies were found that lead to waste water leakage.

Comparative Analysis of Dielectric Properties of Polyvinyl Alcohol and Polyethylene

The article presents a new comparative analysis of the dielectric properties of polyvinyl alcohol (PVA) and polyethylene (PE) at different temperatures and their other physical properties. The characteristic peaks were observed in the FTIR spectra of the polymers. The amounts of carbon and oxygen on PVA’s surface differed from PE. It was hypothesized that these properties could be affected by the increase in temperature and difference in the chemical structures of the polymers. We investigated the dielectric properties of these polymers between 20 °C and 100 °C. Our results revealed that the dielectric properties of these polymers were not the same. The actual permittivity values of PVA at low temperatures were almost constant for all frequency values and increased at higher temperatures with the decrease in frequency. The same pattern concerning the increase of imaginary permittivity of this polymer was observed at low frequencies. The increase of the real and imaginary permittivity of the PVA accompanied the increase in temperature. The actual permittivity of PE was almost constant with the frequency at different temperatures. However, the imaginary permittivity of this polymer showed an increase at low frequencies. The increase in temperature accompanies the increase of the PE’s imaginary permittivity. As expected, the capacitance, like permittivity, changed differently for the polymers. Moreover, an increase in temperature had more effect on the conductivity of PVA than that of PE. The difference in these polymers’ dielectric properties could be due to their chemical structures. The results of this article can be used for further applications of PVA and PE in science and engineering.

Boosted visible light dye-decontamination and colossal dielectric constant features of Bi2O3: Role of In, Cu and Li-dopants

This study focused on improving the optical, dielectric properties, and photocatalytic efficiency of Bi2O3, a prominent photocatalyst with challenges like limited visible light absorption and rapid electron-hole pair recombination. Using an adapted sol-gel technique, pure Bi2O3, In, Cu and Li-doped Bi2O3 visible-light-driven photocatalyst were synthesized. X-ray diffraction (XRD) confirmed monoclinic Bi2O3 formation. The inclusion of In, Cu, and Li ions into the Bi2O3 lattice was evidenced by alterations in diffraction peak intensities, lattice parameters, and changes in average crystallite size. Vibrational spectra corroborated the formation of pure α-Bi2O3 with slight shifts in transmittance bands, aligning with the XRD findings. Morphological investigation via scanning electron microscopy (FE-SEM-EDX) confirmed the purity of the synthesized nanocompositions and unveiled that the doping induces distinct morphological changes in Bi2O3 nanoparticles, resulting in increased porosity and formation of round and needle-like shapes (In-doped), coalescence of particles (Cu-doped), and fused agglomerates with altered particle size distribution (Li-doped). Optical analysis demonstrated a red shift in the band gap energy of α-Bi2O3 (initially 2.90 eV), with In, Cu, and Li doping, resulting in band gaps of 2.77 eV, 2.78 eV, and 2.88 eV, respectively, accompanied by high refractive indices exceeding 2.0, rendering them suitable for optical applications. Both Cu and Li doping led to enhanced relative permittivity (εʹ) values, with the Li-doped sample displaying remarkable εʹ values at low frequencies (up to 1000 Hz). The In, Cu and Li doping has the effect of reducing PL (photoluminescence) emission intensity while simultaneously diminishing radiative recombination and promoting the separation of photogenerated charge carriers. The doped samples demonstrated superior degradation performance, with In-doped and Cu-doped samples achieving degradation efficiencies of 99% and 91%, respectively, within 180 min. This remarkable performance can be attributed to their visible-light-responsive band gaps, increased electron-hole trapping sites, and distinct morphological features.

Excellent microwave absorption of Y2Fe15.5Co0.5Si/paraffin composites by tuning powder particle size

The electromagnetic and microwave absorption properties of Y2Fe15.5Co0.5Si and its paraffin composites have been investigated. It is found that the ball milling time is directly related to the particle size of the powder, which influences the microwave absorption performance and the degree of orientation of the composites. When the particle size of the Y2Fe15.5Co0.5Si powder approaches the grain size, the difference between the in-plane and the out-of-plane anisotropy field of the oriented composite increases. The reflection loss (RL) peak of the oriented composites moves to the low frequency band due to higher complex permeability and complex permittivity values at 0.5–8 GHz. A minimum RL of –52.80 dB, for a thickness of 2.28 mm, at 6.28 GHz is obtained for the Y2Fe15.5Co0.5Si/paraffin composite. The effective absorption bandwidth (EAB: RL ≤ –10 dB) is 5.43 GHz (12.31–17.74 GHz) at 1.12 mm, exceeding many reported microwave absorbing materials. Thus Y2Fe15.5Co0.5Si composites exhibit huge potential for microwave absorption in the Ku band.

Preparation and microwave absorption properties of CoFe2O4/NiCo2O4 composite powders

The magnetic spinel cobalt ferrite (CoFe2O4) powders had the high microwave absorption performance at the large thicknesses on account of the low permittivity. Combining the CoFe2O4 powders with other dielectric loss materials had been suggested to improve their impedance matching and microwave absorption performance. In this work, the microwave absorption performance of the CoFe2O4 powders was enhanced by adding the various amounts of the NiCo2O4 nanoparticles as dielectric loss material. The CoFe2O4-x NiCo2O4 composite powders (x = 0, 12.5, 25, and 50 wt %) were prepared by a facile two-pot solution combustion synthesis method. Although the X-ray diffraction peaks of NiCo2O4 phase were absent, but the decrease of saturation magnetization from 61 to 30 emu/g was related to the amount of NiCo2O4 material. Furthermore, the NiCo2O4 nanoparticles were nucleated and grown on the surface of spongy CoFe2O4 powders because the synthesized CoFe2O4 powders were added to the precursor solution of NiCo2O4 material containing the nickel and cobalt nitrates as oxidants and glycine as organic fuel. The microwave absorption performance was analyzed by measuring the permittivity and permeability spectra which were applied for evaluating the reflection loss versus frequency and thickness. The CoFe2O4-25 wt % NiCo2O4 composite powders had the higher microwave absorption performance including the high reflection loss of −40 dB and broad effective bandwidth of 5.6 GHz of Ku band (12–18 GHz) at a small matching thickness of 1.9 mm. The high microwave absorption performance of the x = 25 wt % sample was attributed to its better impedance matching via a proper combination of the permittivity and permeability values.

Advantages and limitations of active phase silanization in PVDF composites: Focus on electrical properties and energy harvesting potential

AbstractIn order to further improve the performance of 0.94[(Bi0.5Na0.5)TiO3]‐0.06BaTiO3/polyvinylidene fluoride (NBT‐BT/PVDF) flexible composite films prepared by the hot‐pressing method, the effect of surface modification of the NBT‐BT particles on the structure and properties of the films was investigated. Two coupling agents, namely, (3‐aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) were added to enhance dispersion and interfacial adhesion of the active phase powder with the polymer matrix. The highest amount of the electroactive PVDF β‐phase was formed in APTES‐modified samples while in DDTES samples mainly γ‐phase was formed as shown by Fourier‐transform infrared spectroscopy analysis. Differential scanning calorimetry measurements indicated that the addition of filler particles reduced the total crystallinity degree of the PVDF. Dielectric permittivity values as well as dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES‐modified particles led to enhanced breakdown strength of these samples. The highest level of agglomeration in the DDTES‐modified samples induced the deterioration of ferroelectric properties. The highest voltage output of ~15 V and 225 μW of power was obtained for the APTES‐modified harvester, evidencing their potential for energy harvesting applications.Highlights Surface of NBT‐BT particles was successfully modified by the silanization method. NBT‐BT‐PVDF flexible lead‐free composite films were prepared by hot pressing. APTES coupling agent enabled the transformation of PVDF α‐phase into electro‐active β. APTES‐modified samples showed the highest breakdown strength. Notable properties for energy harvesting application found, up to 225 μW of generated power.

Measurement of electrical conductivity of transformer oil based nanofluid

In this article, an attempt was made to evaluate the electrical conductivity of ananofluid based on transformer oil. For this purpose, several nanofluid samples with different concentrations of dielectric silicon dioxide nanoparticles and conductive zinc nanoparticles were prepared. The dielectric permittivity and electrical conductivity of the obtained nanofluids were measured experimentally. After processing the experimental results, a theoretical calculation was made using the Nielsen formula. After the calculation, the results were compared with the experimental data. In the process of comparative analysis, the correspondence of the calculated and experimental values of the dielectric permittivity was noted. There was also a discrepancy between the experimental and calculated values of electrical conductivity. An explanation is proposed for the discovered discrepancy between the calculated and experimental values. Presumably, the main reason for the decrease in electrical conductivity in the experiment is the adsorption of ion particles in the dielectric.

Low-temperature sintering of ZnTiO3 using CaV2O6 as a liquid-forming additive for LTCC applications

CaV2O6 (CV) is investigated as a sintering aid for the low-temperature densification of ZnTiO3 (ZT). The incorporation of 5 vol% of CV drastically decreases the sintering temperature of ZT from 1175 to 825 °C and prevents its decomposition to Zn2TiO4 and TiO2. The densification temperature reaches as low as 690 °C when the concentration of CV approaches 30 vol%. The formation of a eutectic at 687 °C from unreacted V2O5 and TiO2 present in CV and ZT powder, respectively, and the lowering of the melting point of CV in the presence of ZT, as evidenced by DSC analysis, are responsible for the low-temperature densification by liquid phase sintering. The XRD analysis indicates no reaction between the ZT and CV phases in the composites. The SEM analysis shows the presence of CV in the boundaries of ZT grains and a decrease in average grain size from 5.9 to 1.24 μm when the CV concentration increases from zero to 30 vol%. The permittivity value decreases from 24.25 to 22.71, and the loss factor increases from 7.449 × 10−4 to 1.321 × 10−3 when the CV concentration in the composite increases from 5 to 30 vol%. The composite containing 5 vol% CV shows the highest Qu × f value of 9215, a temperature coefficient of the resonance frequency of −51 ppm/°C, a thermal expansion coefficient of 9.3 ppm/°C, and a thermal conductivity of 4.72 Wm−1K−1. The ZT-CV composites are compatible with silver at their sintering temperatures, showing their suitability for LTCC applications.

Calculation of the relative permittivity of Rhodamine 6G using the quantum mechanical method

Background: The article describes a method for calculating the permittivity of organic molecules in quantum mechanics using the well-studied Rhodamine 6G molecule as an example. The study of optical properties of large organic molecules requires not only experimental data but also the use of calculations obtained both analytically and numerically. Objectives: Methods for calculating permittivity as phenomenological characteristics of a sample are to be tested on well-studied molecules to be further applied to more complex nonlinear structures. However, the integral changes need to be approximated in the wave functions of large molecules. Material and methods: The numerical simulations in MATLAB were carried out to be compared with the data from Gaussian 09, which are accurate for such small molecules as Rhodamine 6G. MATLAB calculated permittivity values for the frequency domains corresponding to absorption and fluorescence based on the Fermi golden rule. Hence, any molecule can be represented as a composite quantum mechanical system. Meanwhile, Gaussian 09 used the DFT method to determine permittivity. Results: The Fermi golden rule can be applied due to the representation of the molecule as a complex quantum mechanical system. The proposed numerical methods minimize error by using the Dirac delta function. According to our hypothesis, the sum of the wave function of a particle in a potential well and a particle in a ring equals the wave function of the entire system, thus making it possible to study large molecules. As a result of the calculation for two wavelengths of 337 and 573 nm, the permittivity results calculated using the proposed method in MATLAB are 2.98 and 6.27, respectively. Gaussian 09 calculated the same parameters at 2.85 and 6.23. Conclusion: The resulting datasets show a high degree of correlation. Therefore, the research hypothesis has been confirmed. The selected method also proved efficient, hence the enhancement of luminescence can be achieved by changing the relaxation time of the excited state. Plasmonic nanostructures with predetermined properties will controllably enhance the resulting field by the square of the superposition modulus of their near-field. Consequently, conditions for highly coherent radiation with high intensity and polarization can be predicted and calculated before an experiment is carried out.