Dielectric Properties Of Materials Research Articles

Preparation of modified epoxy resin with high hydrophobicity, low dielectric constant, toughness, and flame retardant by epoxy-functionalized siloxanes

A series of α, ω-dimethylglycidoxypropyl-terminated PDMS oligomer (PDMS-GE) oligomers with different polymerization degrees were synthesized and used to modify the bisphenol-A diglycidyl ether E51 (DGEBA) / 4,4-diaminodiphenylmethane (DDM) epoxy resin, resulting in epoxy resins with high hydrophobicity, low dielectric constant, good impact toughness, low combustion heat release rate, and low total heat release. The combustion heat release rate and total heat release of the material decreased with the increase in the loadings of PDMS-GE. Relative to pure epoxy resin, the composite E51/D30–10, which using DGEBA as the matrix, PDMS-GE with a degree of polymerization of 30 as the modifier in an amount of 10 phr relative to the mass sum of DGEBA, PDMS-GE and DDM, exhibited the best comprehensive performance with a water contact angle of 102.42°, a dielectric strength of 6.49 kV/mm, a dielectric constant of 2.93 at 14.2 GHz, the peak rate of heat release (PRHR) and total heat release (THR) are of 378.3 kW/m2 and 134.4 MJ/m2, respectively. These comprehensive performances underscore the potential of PDMS-GE oligomers in significantly improving epoxy resin properties. When the loadings of PDMS-GE oligomers are less than 5 wt%, PDMS-GE with a lower degree of polymerization can improve the toughness of epoxy resins. The impact strength of the composite E51/D24–5, which uses DGEBA as the matrix, PDMS-GE with a degree of polymerization of 24 as the modifier in an amount of 5 phr relative to the mass sum of DGEBA, PDMS-GE, and DDM, reaches 98.1 kJ/m2, which is about 28.9 % higher than that of pure epoxy resin. The results also indicated that the degree of polymerization of PDMS-GE oligomers has less influence on the dielectric properties and mechanical properties of composite materials.

Size effect of typical hygrothermal properties test values for building insulation materials

Thermal and moisture properties of building insulation materials are crucial input parameters for analyzing thermal and moisture transfer phenomena in building environments. Accurate determination of these parameters under different conditions is essential for the correct application and assessment of materials and envelope structures. However, numerous factors influence thermal and moisture properties, and while extensive research has been conducted on this topic, the effects of specimen size on typical thermal and moisture property test values remain unclear. To address the issue of unreliable data caused by random specimen sizes in thermal and moisture property testing of building insulation materials, this study selects three materials—expanded polystyrene (EPS), extruded polystyrene (XPS), and foamed cement—as test subjects to explore the size effects on typical thermal and moisture property test values. The results indicate that specimen size significantly affects the test values for typical thermal and moisture properties, with only a few experiments showing negligible size effects for certain materials. For foamed cement, recommended specimen sizes for thermal conductivity testing using the guarded hot plate method and the transient plane source method are 300 × 300 × 30 mm and 50 × 50 × 30 mm, respectively. Except for equilibrium moisture absorption experiments, the weight of other moisture property tests is generally represented by thickness > planar dimensions.

Polar-Twisted, Nano-Modulated Nematics: Form Chirality and Physical Properties

Recently, two new polymorphs have been added to the nematic class: the polar-twisted nematic (NPT) in 2016 and the ferroelectric nematic (NF) in 2020. Comprised of achiral molecules, both exhibit local polar ordering and adopt modulated structures, right- and left-handed helical organizations—form chirality—albeit on vastly different dimensional scales; modulations have a ~10 nanometer pitch in the NPT and ~500 nm in the NF. Here, we focus on the structure and symmetries of the NPT phase and the ensuing physical properties. Based on an array of order parameters that fully describe the molecular ordering and the nano-modulations thereof, we present a consistent formulation of the dielectric, optical, surface anchoring, and elasticity properties of the NPT materials. We show that these properties are distinctly different from those associated with an elastically modulated, locally uniaxial, nematic.

Biomass-derived wood foam: a solution for efficient thermal insulation in construction

ABSTRACT The increasing demand for sustainable building materials has highlighted the need for bio-based insulation materials with optimised thermal and mechanical properties. This study investigated the impact of biomass-derived wood foam composition on the thermal and mechanical properties of bio-based insulation materials. Utilising polyvinyl alcohol (PVA) as a binder and sodium dodecyl sulfate (SDS) as a foaming agent and wood fibres as support material, this study optimised the foam's stability by mixing 10.0 g PVA, 9.0 g SDS, 11 g wood fibres to create a stable foam with a stirring speed of 900 rpm, yielded a lightweight material with a density of 139 kg/m3 and thermal conductivity of 0.039 W/m K. The wood foam exhibited a regular porous structure with pore sizes ranging from 25 to 1092 μm, and demonstrated compressive and bending strengths comparable to conventional insulation materials. The study underscores the potential of biomass-derived wood foam as a sustainable and effective insulation solution.

Dielectric Hybrid Optimization Model Based on Crack Damage in Semi-Rigid Base Course

To accurately predict the relative permittivity of cement-stabilized base materials, a study on the dielectric mixing model for cracked base materials was conducted. Based on the electromagnetic mixing theory of multiphase composites, a comprehensive dielectric mixing model of cement-stabilized base materials was derived. The volume ratios and relative permittivity values of the specimen constituents in different cracking states of the cement-stabilized base were determined using industrial CT and a Percometer relative permittivity meter, with comprehensive consideration given to the effects of different initial porosities and crack widths on the dielectric properties. Based on the volumetric and dielectric properties of the base material specimens in both intact and cracked states, as well as the error analysis between the predicted and measured values of the relative permittivity constant, the u-optimal solution of the dielectric mixing model for cement-stabilized base material was determined to be 1. Consequently, an optimization dielectric mixing model for semi-rigid base course materials in a cracked state was developed. The optimization model proposed is suitable for predicting the dielectric properties of cement-stabilized base material with crack widths generally greater than 3 mm during the service life of semi-rigid base course in engineering practice.

Influence of Al2O3 - nano filler on the Vachellia Nilotica blended hybrid epoxy composites: a comprehensive analysis of mechanical, viscoelastic, and dielectric behavior

This work presents the influence of Alumina (Al2O3) Nano powder on the mechanical, dynamic, and dielectric properties of the hybrid epoxy resin composite material containing Vachellia nilotica (VN). The hand lay up method was used to make the composite specimens at different volume fractions of the alumina nano particle filler (3, 6, 9, 12, and 15 v/v%). The Vachellia nilotica content was kept at 12 v/v% in all the samples remaining being epoxy resin. The experimental results indicate that the composite with 9 v/v% Al2O3 showed better mechanical and dielectric properties when compared to other volume percentages. The epoxy composite with the highest glass transition temperature and storage modulus was also the one containing 9 v/v% nano filler. Furthermore, the dielectric test demonstrated that the addition of the nano filler strengthened the dielectric strength of the composite. The structural morphology of the composite's tensile fracture was investigated using scanning electron microscopy (SEM) to investigate the interaction between the epoxy matrix and the fillers in the hybrid composites.

Comparisons of computer simulations and experimental data for capacitive hyperthermia using different split-phantoms

Introduction Several positive clinical trials have demonstrated that capacitive hyperthermia (CHT) improves the effectiveness of radiation therapy for the treatment of various cancer entities. However, the ability of CHT to induce significant heating throughout the body is under debate. Objectives To perform a pilot study involving comparisons of computer simulations and experimental data using different split-phantoms to validate hyperthermia treatment modeling for pre-planning for a clinical CHT system and to investigate the feasibility of split-phantom measurements in capacitive hyperthermia. Materials and methods The CHT system EHY-2030 (Oncotherm, Budapest, Hungary) was used. The system provides two electrode sizes, but only the smaller electrode, indicated as D200 electrode, was investigated in this pilot study. Horizontally and vertically splittable, different multi-slice phantoms with dielectric material properties simulating muscle and electrically low conductive fat were produced and heated. During the heating procedure, temperature-time curves were measured, and thermal images were captured. Specific absorption rate values were derived from the temperature rise (TR) values. Concomitantly, computer field simulations utilizing a detailed CAD-based model of the CHT system were performed using the simulation platform Sim4Life and compared with measurements. Results For the investigated electrode D200 the system power of 75 W was applied, which is half of the maximum power of 150 W and lies in the range of usual values for this electrode applied in patient treatments in our clinic. For 75 W, a heating of 3.6 °C in 6 min in a depth of 1 cm in an agar-based, muscle tissue-equivalent phantom was achieved. The addition of a 1 cm thick, synthetic, low dielectric fat layer reduced the TR up until a depth of 8.5 cm by on average around 38% (from 8.5 cm onwards the absolute local TR is similar, deviations are ≤0.1 °C). In terms of point-to-point absolute SAR comparison (without any normalization), up to a depth of 11 cm in the phantoms central vertical plot, the simulation differs from the measured TR points by on average 25% (ranging from 7% to 36%) for the homogeneous phantom and by on average 43% (ranging from 26% to 60%) for the inhomogeneous phantom. Conclusion Computer simulations and experimental data were compared for the CHT system EHY-2030 using the D200 electrode, applying a thermal imaging technique for different vertically splittable phantoms. This pilot study data can be used as a guidance regarding the expected heating for this commonly used electrode size but also to further elucidate the significance of non-thermal anticancer effects. Further studies are needed for different sizes and geometries of electrodes and phantoms.

Non-linear AC dielectric properties of epoxy composites filled with core–shell SiC particles

Abstract Core–shell structured silicon carbide (SiC)/epoxy (EP) composites exhibit superior non–linear DC conductivity. However, the high voltage alternative current dielectric properties of the composites are rarely reported. In this paper, the time–domain measurement was employed to obtain the basic dielectric characteristics, AC conductivity, and relative permittivity of the SiC/EP and SiC@Al2O3/EP composites under less than the breakdown strength of the SiC/EP (i.e. the amplitude of 1–5 kV mm−1). In addition, in the high AC electric field (i.e. the amplitude of 6–20 kV mm−1), the non–linear AC dielectric properties of the SiC@Al2O3/EP composite are also investigated. The experimental results suggest that the SiC@Al2O3/EP composite shows more obvious non–linear AC dielectric properties than the SiC/EP composite. In the high AC electric field, the AC conductivity of the SiC@Al2O3/EP composite presents the relaxation phenomenon, which is attributed to the excitation field and its derivative. This work lays a foundation for further research on the AC steady–state and transient dielectric properties of the field grading materials, which are widely used to homogenize the nonuniform electric field distribution in many electrical and electronic equipment.

Machine learning-based price prediction for thermal insulation materials: A holistic approach integrating thermophysical, technical, and environmental attributes in the Greek construction market

This study underscores the pressing need to accelerate the energy transition in existing housing to meet the EU’s decarbonization targets. It examines the correlation between thermophysical, technical, and environmental properties of thermal insulation materials and their commercial prices in Greece. Utilizing a dataset of 500 products from technical leaflets, Environmental Product Declarations (EPDs), and market surveys, the study developed six prediction models for material retail prices. A novel aspect of this research lies in quantifying the economic ramifications of insulation material properties through supervised machine learning (ML) techniques. Accurate price prediction models can provide practical applications across stakeholders, including cost estimations for designers, customized recommendations for homeowners, pricing tools for traders, optimization of manufacturing processes, support for policymaking, educational resources for construction professionals, and improved energy efficiency certification payback estimations. Feature analysis showed that total Global Warming Potential (GWP) significantly influences material prices. The Ensemble of Trees and Gaussian Process Regression (GPR) models demonstrated robust performance, with high R2 values of 0.95 in validation and 0.95/0.93 in test sets, indicating reliability without overfitting. Recommendations include integrating more predictors, collaborative model approaches, regular updates, and adopting federated learning techniques for enhanced data privacy and stakeholder cooperation.

Control of dielectric properties of composite materials by editing low dielectric ceramics with anchored structure

Extensive research over the impact of the content of a particular constituent in composites on their electromagnetic wave-absorbing performance has been witnessed. However, an accurate summary regarding the impact of ceramics’ dielectric constant on electromagnetic absorption performance of ceramic/graphene composites is still ad referendum. In this paper, a series of low-dielectric ceramics were synthesized by precisely controlling the proportion of boric acid and subsequently integrated with reduced Graphene nanosheets (RGNSs) to fabricate ceramic/RGNSs composites for efficient electromagnetic wave absorption. The amorphous range of ceramics, which is affected by the boric acid content, controls the dielectric properties that subsequently affect the absorption performance. Increasing the amorphous range of ceramics was found to result in an increase in both maximum value and stability of the actual component of complex permittivity for SiBON/RGNSs composite material. Additionally, tangent values at X and Ku bands also exhibited an increase, leading to an augmented microwave absorption performance (maximum absorption bandwidth: 4.94 GHz; minimum reflection loss: −50.45 dB).

Identification of Alternations in the Structure of Historical Masonry Walls Using the GPR Method Accompanied with Architectural Survey in the Former Piast Gymnasium in Brzeg

Widely used in civil engineering, GPR (ground penetrating radar) is increasingly being used to survey historic structures. However, there are still no conclusive directives on the use of GPR in the identification and diagnosis of masonry structures. The current state of the art allows only on the example of individual case studies, to draw conclusions about the effectiveness of the use of this tool. One such area, where the effective use of GPR has been experimentally confirmed, is the historic architectural survey of a heritage buildings. Due to diversity in the dielectric properties of individual construction materials, it is possible to observe on radargrams the change of electromagnetic wave patterns by materials from different phases. Traditional approach require extensive excavation efforts or core drilling, which may not always be acceptable for conservation reasons. Hence the GPR method could be interesting, non – destructive option for identification and diagnosis of historical masonry walls. The authors used the architectural survey and accompanying excavations at the former Piast Gymnasium in Brzeg to conduct a survey campaign using the GPR method. The brick walls of the building's nave have been scanned. The nave have undergone numerous alterations over hundreds of years. The GPR data has been subjected to adequate post-processing and then correlated with architectural surveys and validated on the basis of available excavations at the site. The authors highlight that GPR surveys, when combined with architectural investigations, offer a less invasive approach to examining historic structures, thereby mitigating the need for problematic excavation work.

Synergistically Constructing High-Dielectric Poly(m-phenylene isophthalamide)/Silica/Cellulose Nanofiber Composite Insulation Paper through Dynamic Covalent Chemistry and Hydrogen Bonding.

The rapid advancement of modern power equipment and high-power devices has imposed increasingly stringent demands upon the mechanical and dielectric properties of electrical insulation materials. Herein, we report a poly(m-phenylene isophthalamide) (PMIA) composite insulating paper with excellent dielectric breakdown strength, reliable mechanical properties, and high thermal stability. Enhanced surface activity of PMIA is achieved through surface modification, facilitating the synergistic integration of modified PMIA (MPMIA), bovine serum albumin (BSA)/silica (SiO2), and cellulose nanofiber (CNF) into composite paper using dynamic covalent bonds and hydrogen bonding. The prepared MPMIA-BSA/SiO2-CNF composite paper exhibits a laminated stacked structure with high tensile strength (32.68 MPa) and strain at break (9.57%). Meanwhile, MPMIA-BSA/SiO2-CNF composites have excellent dielectric breakdown strength (24.75 kV/mm) and good temperature resistance. Therefore, the MPMIA-BSA/SiO2-CNF composite paper has a broad application prospect in the field of high-voltage and high-power electrical equipment insulation.

Dielectric and photocatalytic characteristics of novel CaCu3Ti4O12 modified Ba0.5Sr0.5TiO3-based heterojunction synthesized by wet-chemistry method

The study presents a comprehensive investigation into the synthesis, characterization, and application of barium strontium titanate-calcium copper titanate (BST-CCTO) heterojunction, offering insights into their potential for high-energy-density capacitors and photocatalytic applications. It discusses the synthesis methods for BST, CCTO nanoparticles and their heterojunction. It delves into the structural analysis of prepared heterojunctions using techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of heterojunctions, particularly in the degradation of organic dyes and pharmaceutical waste under visible light, is explored. Results demonstrate the superior photocatalytic efficiency of BST-CCTO heterojunction, i.e., B2 (99.5 % for RhB) compared to individual BST (78.4 %), suggesting potential applications in environmental remediation. This study also explores the development and properties of dielectric materials, particularly focusing on polyvinylidene fluoride (PVDF) and its composites with high-dielectric ceramics such as BST and CCTO. Various aspects of dielectric behavior, including polarization mechanisms and frequency dependence, are also discussed. Dielectric studies reveal the enhanced dielectric constant (50.93 at 1 kHz for 3 wt% loading of B3) of PBCT-3 composite as compared to pure PVDF composite (10 at 1 kHz), attributed to factors such as interface engineering, complementary electrical properties, and grain boundary effects. The mechanisms underlying the interaction between fillers and PVDF matrix are elucidated, highlighting the role of interface engineering and polarization enhancement in optimizing dielectric performance.

Effect of Guest Particles on the Functional Dielectric Properties of Materials for Display Application

AbstractIn this study the dielectric properties are experimentally studied and also analyzed the influence of guest particles on the functional properties of various liquid crystals. The polar and elastic energy of the nanoparticles is found to affect the functional energy of pure suspension. In addition to this, the functional dielectric anisotropy of the dispersed system takes modified form. In this study experiments are performed on various materials to find dielectric anisotropy and also found in good agreement with theoretical explanation.

Effects of Varying Nano-Montmorillonoid Content on the Epoxy Dielectric Conductivity

This study investigates the correlation between the interface structure and macroscopic dielectric properties of polymer-based nanocomposite materials. Utilizing bisphenol-A (BPA) epoxy resin (EP) as the polymer matrix and the commonly employed layered phyllosilicate montmorillonoid (MMT) as the nanometer-scale dispersive phase, nano-MMT/EP composites were synthesized using composite technology. The microstructure of the composite samples was characterized through XRD, FTIR, SEM, and TEM. Changes in the morphology of the nanocomposite interface were observed with varying MMT content, subsequently impacting dielectric polarization and loss. Experimental measurements of the dielectric spectrum of the nano-MMT/EP were conducted, and the influence of the material interface, at different nano-MMT contents, on the dielectric relaxation was analyzed. The study delves into the effect of the nanocomposite interface structure on ion dissociation and migration barriers, exploring the ionic conductivity of nano-MMT/EP. Lastly, an analysis of the impact of different nano-MMT contents on the dielectric conductivity is presented. From the experimental results, the arranging regularity of polymer molecules in the interface area raises. In the matrix, the ion migration barriers decrease significantly. The higher the MMT content in the interface, the lower the migration barrier is. Until the MMT content exceeds the threshold, the agglomerated micro-particles form, which decreases the polymers’ space distribution regularity, and the ions migration barrier raises. According to the changes in the rule of the ions migration barrier with the composite interface structure content, the reason for dielectric conductivity changes can be judged.

Phthalocyanine and metal phthalocyanine are hole transport buffer layers for perovskite solar cell fabrication

This approach allows you to more accurately evaluate the performance of solar panels and identify any prob- lems or degradation in their operation. The LUMO value of mPc closer to the LUMO value of CH3NH3I3PbClx increased conversion energy and short circuit current density (Jsc), which reached a maxi- mum value of 15.97 mA/cm² using the HTL layer of CuPc, and the open circuit voltage (Voc) reached a max- imum at 0.97 V. The change in Jsc corresponds to the fill factor (FF) change. The filling factor (FF) reached a maximum value of 67.35 % when using the HTL layer of CuPc and a minimum value (FF) of 54.23 % when using the HTL layer of H2Pc. The lowest series resistance (R1) and interface resistance (R3) of 11.2 and 39.9 Ohms, respectively, were shown with the HTL layer of CuPc, Capacitive element CPE1 — 305 pF, Ca- pacitive element CPE2 — 0.95 pF. CPE (Constant Phase Element) is an element used in equivalent circuits to describe the non-ideal dielectric properties of materials. The decrease in CPE1 may indicate a decrease in the heterogeneity of the dielectric properties of the perovskite material after coating with different HTL mPc lay- ers. This may be due to changes in structure or mutual actions between layers as a result of exposure to dif- ferences in energy levels.

Analysis of Thermal Properties of Materials Used to Insulate External Walls.

This article emphasizes the significance of understanding the actual thermal properties of thermal insulation materials, which are crucial for avoiding errors in building design and estimating heat losses within the energy balance. The aim of this study was to analyse the thermal parameters of selected thermal insulation materials, particularly in the context of their stability after a period of storage under specific conditions. The materials chosen for this study include commonly used construction insulations such as polystyrene and mineral wool, as well as modern options like rigid foam composites. Experimental studies were conducted, including the determination of the thermal conductivity coefficient λ, as well as numerical analyses and analytical calculations of heat flow through a double-layer external wall with a window. The numerical analyses were performed using the TRISCO software version 12.0w, based on the finite element method (FEM). A macrostructural analysis of the investigated materials was also performed. The findings indicated that improper storage conditions adversely affect the thermal properties of insulation materials. Specifically, storing materials outdoors led to a deterioration in insulating properties, with an average reduction of about 4% for the standard materials and as much as 19% for the tested composite material. Insufficient understanding of the true thermal properties of insulation materials can result in incorrect insulation layer thickness, degrading the fundamental thermal parameters of external walls. This, in turn, increases heat loss through major building surfaces, raises heating costs, and indirectly contributes to greenhouse gas emissions.

Innovative silica aerogel fiberglass walls and roofs: A path to lower carbon emissions and higher energy savings

ABSTRACT Buildings account for a significant portion of global energy use and consumption. Buildings have substantial energy consumption due to the use of heating, ventilation, and cooling systems. It is evident that the insulation materials used in the design of building envelopes can efficiently reduce the cost of air conditioning by reducing external heat gains and losses. Additionally, the use of environmentally friendly and cost-effective can be beneficial from an environmental standpoint. This paper aims to evaluate the potential for cost savings in the air conditioning of buildings incorporated with silica aerogel fiberglass insulation in hollow concrete bricks (wall) and hollow roof tile (roof). Silica aerogel fiberglass insulation is extensively used for heat insulation purposes, including building insulations, due to its superior thermal insulation and flame retardant properties. The thermo-physical properties of silica fiberglass insulation and building materials were determined experimentally as per ASTM D 5334 standards. Twenty distinct building design concepts are investigated in this study, each featuring insulation-integrated concrete blocks composed of silica aerogel fiberglass: (WEM1) insulation layer in the outer side, (WEM2) insulation layer in the center, (WEM3) insulation layer in the inner side, (WEM4) insulation layers in the outer-middle, (WEM5) insulation layers in the middle-inner, and (WEM6) insulation layers in the outer-inner sides. Additionally, two arrangements of insulation-stuffed roof tiles, REM1 above the RCC and REM2 below the RCC. In addition, novel building designs integrated with insulation were analyzed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). Thermo-economic analysis of novel wall and roof designs with silica fiberglass insulation materials on air-conditioning costs, carbon dioxide emissions, and payback time are compared with conventional roof and wall patterns. The thermo-economic analysis was carried out based on the number of degree-hours of heating and cooling to determine the building’s annual energy usage. The building model arrangement (WEM6-REM1), which consists of an insulation composite wall (WEM6) and insulation roof tile (REM1), demonstrated the greatest annual air conditioning cost savings of 3.4 $/m2/year and 1.74 $/m2/year when compared to conventional building design for climatic conditions of Kurnool and Gauhati. The building model arrangement (WEM6-REM1) composed of silica fiberglass aerogel insulation exhibits the highest reduction in carbon emissions of 65 kg/kWh and 33 kg/kWh, when compared to conventional building design analyzed in both hot-arid; (Kurnool) and composite (Gauhati) climatic conditions. The placement of insulation in the roof alone (REM1) has the shortest payback duration of 2.15 years. The results of this study point to a viable approach to enhancing building design decision-making and narrowing the performance gap in sustainable and energy-efficient strategies.

Crystal Structure, Microstructure, and Dielectric and Electrical Properties of Ceramic Material Prepared Using Volcanic Ash

In the present work, the electrical and dielectric properties of ceramic samples prepared from volcanic ash were investigated. For this purpose, ceramic samples were prepared using milled volcanic ash with a binder material at a sintering temperature of 950 °C for 2 h. The chemical content of the milled volcanic ash was investigated using XRF. Differential thermal analysis and thermogravimetry were performed to determine the firing conditions. The crystalline phases and microstructures of the ceramic samples were investigated using XRD and SEM, respectively. Finally, the electrical and dielectric properties of the obtained samples were evaluated at a frequency ranging from 1 × 102 to 4 × 106 Hz and temperatures ranging from room temperature to 800 °C. The XRD results revealed that the ceramic samples contained three main phases: albite, hematite, and augite. Moreover, the microstructures of the samples exhibited a large crystal size with a dense surface. The conductivities and dielectric constants of the samples remained stable up to 500 °C. The real and imaginary parts of the dielectric constant decreased with an increase in frequency and increased with an increase in temperature. The results indicated that ceramics based on volcanic ash are promising for use in technological applications such as high-voltage power insulators.

Preparation and Electrorheological Behavior of Rare‐Earth La Ion Doping MIL‐125 Nanoparticles

Herein, rare‐earth element (lanthanum)‐doped MIL‐125 is synthesized via the solvothermal method. The morphology, physicochemical structure, specific surface area, and other characteristics of the synthesized material are characterized via scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, Brunauer Emmett Teller, X‐ray photoelectron spectroscopy, element mapping, etc. It is observed that appropriate La doping enhances the dielectric mismatch and conductive mismatch levels of the material. This enhancement leads to a stronger interface polarization capability, thereby influencing the material's dielectric properties. Ultimately, the electrorheological fluids with La‐doped MIL‐125 as the dispersive phase show an obvious electrorheological effect.