Determination of dielectric properties of lead-contaminated soils: Potential application to soil remediation.

This research investigated the effectiveness of radio frequency (RF) heating as a treatment for lead-contaminated soil, assessing its impact through dielectric constant measurements. Using water-soluble lead (II) acetate trihydrate, the study analyzed the impact of RF heating on soil dielectric properties under various soil moisture conditions (high, medium, and low) and electric field strengths (112.5, 150, 225, and 450 kV/m). The results indicated that soil temperature increased with lead concentration, highlighting significant changes in soil thermodynamics. Under high-humidity conditions, temperature increases were more pronounced, suggesting that higher lead concentrations elevate soil temperatures. Moreover, RF heating consistently reduced the dielectric constant as lead concentration increased, which was especially evident at higher electric field strengths. The study found that the soil resistivity approached that of uncontaminated soil, particularly at 450 kV/m electric field strength, with the highest removal rate of 46.154%. This investigation provides valuable insights into the application of RF heating for soil quality improvement in lead-contaminated environments, demonstrating how dielectric properties can reflect those of uncontaminated soil.

A wideband model to evaluate the dielectric properties of biological tissues from magnetic resonance acquisitions.

OBJECTIVE: Aim of this work is to illustrate and experimentally validate a model to evaluate the dielectric properties of biological tissues on a wide frequency band using the Magnetic Resonance Imaging (MRI) technique. APPROACH: The dielectric behaviour of biological tissues depends on frequency, according to the so-called relaxation mechanisms. The adopted model derives the dielectric properties of biological tissues in the frequency range 10 MHz - 20 GHz considering the presence of two relaxation mechanisms whose parameters are determined from quantities derived from MRI acquisitions. In particular, the MRI derived quantities are the water content and the dielectric properties of the tissue under study at the frequency of the MR scanner. MAIN RESULTS: The model was first theoretically validated on muscle and fat using literature data in the frequency range 10 MHz - 20 GHz. Results showed capabilities of reconstructing dielectric properties with errors within 16 %. Then the model was applied to ex vivo muscle and liver tissues, comparing the MRI-derived properties with data measured by the open probe technique in the frequency range 10 MHz - 3 GHz, showing promising results. SIGNIFICANCE: The use of medical techniques based on the application of electromagnetic fields is significantly increasing. To provide safe and effective treatments, it is necessary to know how human tissues react to the applied electromagnetic field. Since this information is embedded in the dielectric properties of biological tissues, an accurate and precise dielectric characterization is needed. Biological tissues are heterogenous, and their characteristics depend on several factors. Consequently, it is necessary to characterize dielectric properties in vivo for each specific patient. While this aim cannot be reached with traditional measurement techniques, through the adopted model these properties can be reconstructed in vivo on a wide frequency band from non-invasive MRI acquisitions.

Characterization of dielectric properties and their impact on MAS-DNP NMR applications.

The dielectric properties of materials play a crucial role in the propagation and absorption of microwave beams employed in Magic Angle Spinning - Dynamic Nuclear Polarization (MAS-DNP) NMR experiments. Despite ongoing optimization efforts in sample preparation, routine MAS-DNP NMR applications often fall short of theoretical sensitivity limits. Offering a different perspective, we report the refractive indices and extinction coefficients of diverse materials used in MAS-DNP NMR experiments, spanning a frequency range from 70 to 960 GHz. Knowledge of their dielectric properties enables the accurate simulation of electron nutation frequencies, thereby guiding the design of more efficient hardware and sample preparation of biological or material samples. This is illustrated experimentally for four different rotor materials (sapphire, yttria-stabilized zirconia (YSZ), aluminum nitride (AlN), and SiAlON ceramics) used for DNP at 395 GHz/1H 600 MHz. Finally, electromagnetic simulations and state-of-the-art MAS-DNP numerical simulations provide a rational explanation for the observed magnetic field dependence of the enhancement when using nitroxide biradicals, offering insights that will improve MAS-DNP NMR at high magnetic fields.

Microwave dielectric properties of normal, fibroelastotic, and malignant human lung tissue.

Technological development of microwave treatment and detection techniques for lung cancer requires accurate and comprehensive knowledge of the microwave dielectric properties of human lung tissue. We characterize the dielectric properties of room temperature human lung tissue from 0.5 to 10 GHz for three lung tissue groups: normal, fibroelastotic, and malignant. We fit a two-pole Debye model to the measured frequency-dependent complex permittivity and calculate the median Debye parameters for the three groups. We find that malignant lung tissue is approximately 10% higher in relative permittivity and conductivity compared to normal lung tissue; this trend matches previously reported normal versus malignant data for other biological tissues. There is little contrast between benign lung tissue with fibroelastosis and malignant lung tissue. We extrapolate our data from room temperature to 37 °C using a temperature-dependence model for animal lung tissue and use the Maxwell-Garnett dielectric mixing model to predict the dielectric properties of inflation-dynamic human lung tissue; both approximations correspond with previously reported dielectric data of bovine and porcine lung tissue.

Near-Zero Temperature Coefficient of Resonance Frequency in Rare-Earth Titanates via the Phase Transition Strategy.

This study presents an approach to achieve a near-zero temperature coefficient of resonance frequency (τf) in rare-earth titanate microwave dielectric ceramics (MWDCs) by inducing a phase transition. By Zr4+ substitution at the B site, a series of Sm2Ti1-xZrxO5 (0.02 ≤ x ≤ 0.55) ceramics are synthesized using the solid-state method to intentionally alter the radius ratio of the A/B sites, realizing in a controlled phase transition from orthorhombic (Pnma) to biphasic coexistence and ultimately to cubic (Fd3̅m) structure. The phase composition is rigorously identified through X-ray diffraction (XRD) Rietveld refinement, high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and Raman spectroscopy. A comprehensive analysis is conducted to elucidate the relationships between factors such as ionic polarizability, packing fraction, bond valence, complex chemical bonding, and far-infrared reflectivity spectra with microwave dielectric properties. The results demonstrate that these ceramics exhibit a broad range of permittivity (14.30-23.18), high-quality factors (14,828-22,300 GHz), opposite temperature coefficient of resonance frequency (-16.0 to + 22.4 ppm/°C), and nice thermal conductivity (1.81-2.76 W·m-1·K-1), particularly at x = 0.30 with a near-zero τf value of +1.6 ppm/°C. The findings not only provide insights into designing MWDCs with a near-zero τf but also offer a promising route for developing advanced microwave materials with improved performance and reliability.

Eco-friendly synthesis, characterization, and properties of copper oxide nanoparticles in cashew gum/polypyrrole blend for energy storage applications.

Conducting biopolymer blend nanocomposites of cashew gum (CG) and polypyrrole (PPy), with varying concentrations of copper oxide (CuO) nanoparticles were synthesized through an in-situ polymerization method using water as a sustainable solvent. The formation of blend nanocomposites was characterized using UV-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). UV spectroscopy revealed a significant reduction in absorption intensity with the addition of CuO, indicating enhanced optical properties. FT-IR and XRD analysis confirmed the successful incorporation of CuO into the CG/PPy blend. FE-SEM images revealed the uniform distribution of nanoparticles throughout the biopolymer blend, particularly in the 7 wt% sample. TGA and DSC results demonstrated a significant enhancement in thermal stability, increasing from 352 °C to 412 °C and a rise in the glass transition temperature from 89 °C to 106 °C in the blend nanocomposites. The dielectric constant, dielectric loss, impedance, Nyquist plot, electrical conductivity, and electric modulus were extensively examined at different temperatures and frequencies. The dielectric constant of the CG/PPy blend increased from 2720 to 92,950 with the addition of 7 wt% CuO, measured at 100 Hz. The improved glass transition temperature, thermal stability, and superior electrical properties imply potential usage of the developed nanocomposite in nanoelectronics and energy storage applications.

Structural, morphological, dielectric, electric and magnetic properties of Ba 1 - x Dy 2 x / 3 Ti 0.98 Mn 0.02 O 3 ceramics for multifunctional applications.

Herein, the standard solid-state reaction process was employed to synthesize the polycrystalline Ba1-xDy2x/3Ti0.98Mn0.02O3 (x = 0.0000-0.0085) ceramics and each composition was sintered at 1200 °C for 3 h. The structural, morphological, electrical, and magnetic properties were carried out by the X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), impedance analyzer, and vibrating sample magnetometer (VSM) to investigate the influence of doping of Dy 3+ (low concentration) and Mn4+ in BaTiO3 simultaneously. The XRD study confirmed the formation of perovskite structure with tetragonal symmetry of the prepared solid solution. The magnitude of the porosity (P%) decreased from 13.22 to 9.49 with increasing content of Dy and x = 0.0080 sample showed the lowest value. The mean grain size was estimated in the micrometer range, with values ranging from 0.5713 to 0.1457 µm. The highest grain size determined for the x = 0.0070 sample was 0.5713 µm. The Brunauer-Emmett-Teller (BET) adsorption isotherm measurements were used to estimate the specific surface area; the result was 24.181 m2/g for x = 0.007 composition. For the compound with x = 0.0070 the maximum recorded dielectric constant was found to be 6 × 103 at 103 Hz. A relatively lower dielectric loss (<5 %) was observed. The Nyquist plot illustrated that only the grain boundary effect is significant for the conduction process in the studied compositions. The present solid solution revealed better magnetic results compared to other reported ceramics similar to the prepared constituents. The optimum value of saturation magnetization (0.371 emu/g) was obtained for x = 0.0080 composition. Among the synthesized Dy doped samples x = 0.0075 composition displayed a significant complex initial permeability ( µ i / ). An enhanced relative quality factor (RQF) was seen with increasing frequency and the highest relative quality factor was noticed (>100) for the x = 0.0075 sample at 108 Hz. The studied materials could be employed as an environmentally acceptable alternative to the hazardous lead (Pb)-based multiferroic substance.

Highly Anisotropic Thermally Conductive Dielectric Polymer/Boron Nitride Nanotube Composites for Directional Heat Dissipation.

An ideal dielectric material for microelectronic devices requires a combination of high anisotropic thermal conductivity and low dielectric constant (ɛ') and loss (tan δ). Polymer composites of boron nitride nanotubes (BNNTs), which offer excellent thermal and dielectric properties, show promise for developing these dielectric polymer composites. Herein, a simple method for fabricating polymer/BNNT composites with high directional thermal conductivity and excellent dielectric properties is presented. The nanocomposites with directionally aligned BNNTs are fabricated through melt-compounding and in situ fibrillation, followed by sintering the fibrous nanocomposites. The fabricated nanocomposites show a significant enhancement in thermal properties, with an in-plane thermal conductivity (K‖) of 1.8 Wm-1K-1-a 450% increase-yielding a high anisotropy ratio (K‖/K⊥) of 36, a 1700% improvement over isotropic samples containing only 7.2 vol% BNNT. These samples exhibit a 120% faster in-plane heat dissipation compared to the through-plane within 2 s. Additionally, they display low ɛ' of ≈3.2 and extremely low tan δ of ≈0.014 at 1 kHz. These results indicate that this method provides a new avenue for designing and creating polymer composites with enhanced directional heat dissipation properties along with high K‖, suitable for thermal management applications in electronic packaging, thermal interface materials, and passive cooling systems.

Application of radio frequency energy in processing of fruit and vegetable products.

Thermal processing is commonly employed to ensure the quality and extend the shelf-life of fruits and vegetables. Radio frequency (RF) heating has been used as a promising alternative treatment to replace conventional thermal processing methods with advantages of rapid, volumetric, and deep penetration heating characteristics. This article provides comprehensive information regarding RF heating uniformity and applications in processing of fruit and vegetable products, including disinfestation, blanching, drying, and pasteurization. The dielectric properties of fruits and vegetables and their products have also been summarized. In addition, recommendations for future research on RF heating are proposed to enhance practical applications for fruits and vegetables processing in future.

Dielectric Response of ZnO/PMMA Nanocomposites with Atmospheric Pressure Plasma-Modified Surfaces.

In this work, the effect of etching the surface of polymer matrix nanocomposites with atmospheric pressure plasma targeting to achieve enhanced dielectric properties was investigated. Polymer nanocomposites, with varying reinforcing phase content, were modified by atmospheric-pressure plasma resulting in an increase in the surface filler's concentration. Polymethyl methacrylate (PMMA) matrix nanocomposites reinforced with zinc oxide (ZnO) nanoparticles were prepared and dielectrically studied as a function of the nanoparticle content and the plasma modified surfaces. The electrical response of the composite systems was studied by means of Broadband Dielectric Spectroscopy (BDS) over a wide range of temperatures and frequencies. The dielectric permittivity increased with the embedded phase content and with plasma surface treatment. Energy density followed the same trend as dielectric permittivity, and the plasma-treated nanocomposite with the higher ZnO content exhibited approximately 27% higher energy density compared to the unreinforced matrix.

Reconstruction of the Permittivity of Ex Vivo Animal Tissues in the Frequency Range 1-20 GHz Using a Water-Based Dielectric Model.

Several medical techniques are based on the application of electromagnetic fields (EMFs) on the human body with therapeutic and/or diagnostic aims. The response of human tissues to the applied EMF is mediated by the tissues' dielectric properties, which must therefore be characterized at the frequencies of the considered technique. Due to the heterogeneity and complexity of biological tissues, it is necessary to know their properties in vivo for the specific condition of interest. Traditional techniques for the dielectric characterization of biological tissues are invasive and, as such, not adoptable for this aim. Accordingly, alternative sensors and/or sensing methods are needed. Recently, a new wideband spectroscopy technique was proposed, based on quantities derived from the Magnetic Resonance (MRI) signal. Among these quantities, the water content was proposed to evaluate the dielectric properties at frequencies around a few GHz. This work verifies the possibility of deriving tissues' dielectric properties in the frequency range of 1-20 GHz based on knowledge of the water content. The water content was retrieved through a dehydration procedure for five different ex vivo tissues. The achieved results were compared with references from the literature.

Synthesis, the Reversible Isostructural Phase Transition, and the Dielectric Properties of a Functional Material Based on an Aminobenzimidazole-Iron Thiocyanate Complex.

By introducing disordered molecules into a crystal structure, the motion of the disordered molecules easily induces the formation of multidimensional frameworks in functional crystal materials, allowing for structural phase transitions and the realization of various dielectric properties within a certain temperature range. Here, we prepared a novel ionic complex [C7H8N3]3[Fe(NCS)6]·H2O (1) between 2-aminobenzimidazole and ferric isothiocyanate from ferric chloride hexahydrate, ammonium thiocyanate, and 2-aminobenzimidazole using the evaporation of the solvent method. The main components, the single-crystal structure, and the thermal and dielectric properties of the complex were characterized using infrared spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder XRD, thermogravimetric analysis, differential scanning calorimetry, variable-temperature and variable-frequency dielectric constant tests, etc. The analysis results indicated that compound 1 belongs to the P21/n space group. Within the crystal structure, the [Fe(NCS)6]3- anion formed a two-dimensional hydrogen-bonded network with the organic cation through S···S interactions and hydrogen bonding. The disorder-order motion of the anions and cations within the crystal and the deformation of the crystal frameworks lead to a significant reversible isostructural phase transition and multiaxial dielectric anomalies of compound 1 at approximately 240 K.

Spectral and conductivity measurements insights on loading mechanisms of DMSO/water-kaolin complexes.

Kaolin, a naturally occurring clay mineral renowned for its distinctive properties, holds significant importance across various industries. The integration of dimethyl sulfoxide (DMSO) into kaolin matrices, both in the presence and absence of water, has been extensively explored for its potential to enhance material characteristics. Addressing debates surrounding the proposed adsorption mechanism for the type I structure of DMSO, this study undertook a comprehensive physicochemical characterization of DMSO-kaolin complexes (DMSO-KCs) derived from untreated (UnK) and HCl-treated (HK) Egyptian ore, with a focus on elucidating the loading mechanism facilitated by water. Key insights gleaned from electrical conductivity, dielectric constant, and Fine Testing Technology - Fourier-transform infrared (FTT-FTIR) measurements, shedding light on the bonding nature of DMSO-KCs. FTT-FTIR analysis revealed two stages of water departure at 180 °C, with the final stage coinciding with the release of pyrolysis gases, confirming the catalytic degradation of DMSO. Through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), two distinct bonding types of DMSO molecules with kaolinite were identified: amorphous adsorbed (type I) and lattice-oriented intercalated (type II). Electrical characteristic evaluations within the temperature range of room temperature (RT) to 260 °C and frequency range of 42 Hz-1 MHz revealed that DMSO intercalation enhances the electrical properties of kaolin. Hydrated DMSO-KCs exhibited higher values of σac and ɛ' compared to non-hydrated samples. The activation energy (Ea) values for HCl-treated samples were smaller than those of untreated ones. Alternating current (AC) conductivity analysis indicated predominantly ionic behavior with frequency and temperature dependency in both HCl-treated and untreated kaolin. Our findings substantiate the adsorption mechanism of Type I DMSO, highlighting its amorphous nature, instability, and catalytic degradation over time, in contrast to the intercalated type II. This elucidation is pivotal for understanding the behavior of DMSO-KCs across diverse applications, including electronics, ceramics, and materialsscience.

Dielectric characterisation of human adrenal glands and adrenal tumours for the development of microwave ablation technologies for hypertension treatment.

Adrenal gland-induced hypertension results from underlying adrenal gland disorders including Conn's syndrome, Cushing's syndrome, and Pheochromocytoma. These adrenal disorders are a risk for cardiovascular and renal morbidity and mortality. Clinically, treatment for adrenal gland-induced hypertension involves a pharmaceutical or surgical approach. The former presents very significant side effects whereas the latter can be ineffective in cases where the adrenal disorder reoccurs in the remaining contralateral adrenal gland. Due to the limitations of existing treatment methods, minimally invasive treatment options like microwave ablation (MWA) have received significant attention for treating adrenal gland disorders. A precise comprehension of the dielectric properties of human adrenal glands will help to tailor energy delivery for MWA therapy, thus offering the potential to optimise treatments and minimise damage to surrounding tissues. This study reports the ex vivo dielectric properties of human adrenal glands, including the cortex, medulla, capsule, and tumours, based on the data obtained from four patients (diagnosed with Conn's syndrome, Cushing's syndrome, and Pheochromocytoma) who underwent unilateral adrenalectomy at the University Hospital Galway, Ireland. An open-ended coaxial probe measurement technique was used to measure the dielectric properties for a frequency range of 0.5-8.5 GHz. The dielectric properties were fitted using a two-pole Debye model, and a weighted least squares method was employed to optimise the model parameters. Moreover, the dielectric properties of adrenal tissues and tumours were compared across frequencies commonly used in MWA, including 915 MHz, 2.45 GHz, and 5.8 GHz. The study found that the dielectric properties of adrenal tumours were influenced by the presence of lipid-rich adenomas, and the dielectric properties of Cushing's syndrome tumour were lowest in comparison to the tumours in patients diagnosed with Conn's syndrome and Pheochromocytoma. Furthermore, a notable difference was observed in the dielectric properties of the medulla and cortex among patients diagnosed with Conn's syndrome, Cushing's syndrome, and Pheochromocytoma. These findings have significant implications for the diagnosis and treatment of adrenal tumours, including the optimisation of MWA therapy for precise ablation of adrenal masses.

Peculiarities of Electric and Dielectric Behavior of Ni- or Fe-Doped ZnO Thin Films Deposited by Atomic Layer Deposition.

The physical properties of ZnO can be tuned efficiently and controllably by doping with the proper element. Doping of ZnO thin films with 3D transition metals that have unpaired electron spins (e.g., Fe, Co, Ni, etc.) is of particular interest as it may enable magnetic phenomena in the layers. Atomic layer deposition (ALD) is the most advanced technique, which ensures high accuracy throughout the deposition process, producing uniform films with controllable composition and thickness, forming smooth and sharp interfaces. In this work, ALD was used to prepare Ni- or Fe-doped ZnO thin films. The dielectric and electrical properties of the films were studied by measuring the standard current-voltage (I-V), capacitance-voltage (C-V), and capacitance-frequency (C-f) characteristics at different temperatures. Spectral ellipsometry was used to assess the optical bandgap of the layers. We established that the dopant strongly affects the electric and dielectric behavior of the layers. The results provide evidence that different polarization mechanisms dominate the dielectric response of Ni- and Fe-doped films.

Electrochemical Impedance Spectroscopy in the Determination of the Dielectric Properties of Tau-441 Protein for Dielectrophoresis Response Prediction.

This study employs electrochemical impedance spectroscopy (EIS) to probe the behavior of Tau-441 protein, a key component implicated in Alzheimer's disease. Through meticulous experimentation and analysis, the impedance of Tau-441 protein suspension revealed a conductivity peak value of 1.02 S/m. The study demonstrates a high level of specificity and selectivity, particularly within the challenging nanomolar concentration range. Additionally, the EIS method enabled the prediction of Tau-441 protein's dielectrophoresis (DEP) response and the determination of the associated frequency range of 1 kHz to 1 MHz. These findings contribute to advancing our understanding of the molecular intricacies surrounding Tau-441 and hold promise for unraveling implications related to Alzheimer's disease. This study establishes a robust foundation for future research on neurodegenerative disease and biosciences, offering valuable insights into the electrochemical dynamics of Tau-441 protein.

Elucidation of structural, electromagnetic, and optical properties of Cu-Mg ferrite nanoparticles.

Copper doped magnesium ferrite, Mg1-xCuxFe2O4(x = 0.0-1.0) nanomaterials were synthesized via. sol-gel method sintered at 600 °C for 2 h. The synthesized materials were characterized using modern sophisticated techniques viz. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy, Energy dispersive x-ray spectroscopy (EDS), Vibrating sample magnetometer, UV-visible diffuse reflectance spectra and Impedance analyzer. XRD analysis revealed that all the samples were single phase cubic spinel structure with Fd3m space group and investigated the change in structural parameters with copper concentration. The average crystallite size in the range of 11-23 nm and lattice parameters decrease with increasing Cu doping, due to the cationic distribution and ionic radius. The SEM images show the agglomeration of the particles with spherical like shape and elemental percentage were obtained from EDX. The saturation magnetization showed an increasing trend with increasing Cu concentration at a certain level and then decreases due to the rearrangement of cations at tetrahedral and octahedral sites. The Coercivity, Retentivity and magnetic crystalline anisotropy increase with changing dopant concentration. The magnetic measurements showed enhanced saturation magnetization at certain level (28.96emu/gm) and increase in coercivity up to 1102 Oe with changing dopant concentration. The estimated band gap energy is found to increase with Cu content. The dielectric constant, dielectric loss and impedance show normal behavior of ferrite. The frequency dependent dielectric constant decrease and tan delta shows a relaxation behavior at low frequencies. The synthesized nano Mg-Cu nanoparticles will be applied as humidity sensor, gas sensor, microwave devices and photocatalyst.

The role of thermal treatment and formulation on modifying the structural nature and optimizing certain physical features of coprecipitated superparamagnetic Co-Mn-Cr spinel ferrite.

Examining the composition and heat treatment effects of co-precipitated Co0.7Mn0.3CrxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1) ferrite nanoparticles provides valuable insights into the structural, morphological, optical, magnetic, and electrical properties of these materials. X-ray diffraction (XRD) and Rietveld refinement analyses confirm the spinel cubic crystalline phase of the samples, indicating the formation of well-defined crystal structures. Transmission electron microscope micrographs manifest the nanoscale nature of the produced specimens and their narrow particle size distribution with a small standard deviation. This uniformity is often desirable in many applications because it confirms the similarity of the properties and behaviors of the nanoparticles. The Fourier transform infrared spectroscopy study suggests that the substitution of Cr3+ ions at octahedral sites influences molecular stability. Annealing causes a slight expansion in bond length and a subsequent decrease in stability. The presence of Cr3+ ions enhances the strength of the specimens, while annealing weakens them. This indicates a fine balance between composition and processing conditions in determining the strength of the materials. The estimated optical indirect bandgap undergoes a redshift by adding Cr3+ ions. Annealing at elevated temperatures reduces the bandgap due to the quantum confinement effect, indicating the tunability of optical properties through compositional and thermal control. Samples with x ≥ 0.6 exhibit nearly zero coercivity, indicating superparamagnetic behavior, which have promising applications. The preference of Cr3+ ions to occupy octahedral B-sites influences the magnetic behavior of the materials. The dielectric polarization and dielectric loss improved by adding Cr3+ ions, while the alternating current conductivity decreased. From impedance spectroscopy, the real and imaginary parts, Z' and Z", were increased by increasing Cr content. Furthermore, the annealing process greatly affects the electrical properties of the specimens. Overall, the study emphasizes the intricate relationship between composition, annealing conditions, and the resulting structural, magnetic, and electrical properties of Co-Mn-Cr ferrite nanoparticles, providing significant observations for the development of tailored materials for diverse applications in electronics, magnetics, and medicine.

The effect of Zn doping on the structure, phase transformation and electric properties of 0.5BZT-0.5BCT materials.

In the current study, an improved method of adding Zn ion doping to the 0.5BZT-0.5BCT-based films with high pyroelectric properties was designed. Under different Zn ion doping ratios, the structure, dielectric constant, phase transition relationship and other characteristics of the test product were analyzed experimentally to obtain the optimal ratio parameters. The experimental results demonstrate that the dielectric properties of the 0.5BZT-0.5BCT-xZn-based films proposed in this study can be far superior to those of other films under the optimal preparation process. The optimal dielectric properties and ferroelectric properties are obtained when the doped data are 0.008. Considering the comprehensive dielectric and energy storage capacity, the optimal doping ratio is 0.01, which can take into account dielectric data and energy storage performance. The energy storage density is 1.842 J / c m 3 , and the energy storage efficiency exceeds 30%. From 0 to 0.02, the properties of the material, such as the hysteresis loop and phase transition relationship are excellent. The properties of the materials studied in this study are excellent, and they are excellent candidate materials for the future application of ferroelectric materials, and provide ideas for related work.

Extraction of rare earth Eu from waste blue phosphor strengthened by microwave alkali roasting.

Spent phosphor is an important secondary resource for extracting rare earth elements. Microwave absorption properties and enhanced extraction of Eu from blue phosphor by microwave alkali roasting were studied. Dielectric properties of alkali roasting system were measured by resonator perturbation method. Dielectric constant increases linearly from 250 °C until it reaches a peak at 400 °C. The dielectric loss reaches a higher value at 400-550 °C, due to the strong microwave absorption properties of molten alkali and roasted products. Effects of roasting temperature, roasting time and alkali addition amount on Eu leaching were investigated. The phosphor was completely decomposed into Eu2O3, BaCO3 and MgO at 400 °C. The alkaline decomposition process of phosphor is more consistent with diffusion control model with Eα being 28.9 kJ/mol. Effects of the main leaching conditions on Eu leaching were investigated. The leaching kinetic of Eu was in line with diffusion control model with Eα being 5.74 kJ/mol. The leaching rules of rare earths in the mixed phosphor were studied. The results showed that the presence of red and green phosphor affected the recovery of blue phosphor. The optimum process parameters of rare earth recovery in single blue phosphor and mixed phosphor were obtained, and the recovery of Eu were 97.81% and 94.80%, respectively. Microwave alkali roasting promoted the dissociation of phosphor and leaching of rare earths. The results can provide reference for the efficient and selective recovery of rare earths in phosphors.