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The existing problem of photovoltaics (PV) seeks new efficient materials that can feed to the next level solar power generation under access universally. This study proposed the magnetic nanoparticles (NPs) of barium mono ferrite BaFe2O4 with transition metal Zn, nominated for its electrical properties to explore incorporation's effect on structural, physicochemical, and magnetic properties to develop the dynamics of charge carriers, stability, and possibly tackling the need of new competent materials for PV technology. ZnO nanoparticles are widely used in solar cells with wide band gap (3.1 eV to 3.37 eV), an optimized value as low as 1.35 eV was successfully achieved in the present work. BaFe2O4 NPs exposing orthorhombic system for photovoltaic application was surveyed for the first time to the best of our knowledge. The nanoparticles of Ba1−xZnxFe2O4 (x = 0.0, 0.2, 0.3, 0.5) scheme have been prepared by the sol–gel auto-combustion method. An inclusive structural examination has been executed for prepared samples by X-ray diffraction and RAMAN study. The rarely found orthorhombic crystal system with Pnma-62 was identified and a 3D visualization was drawn for the first time for BaFe2O4. The magnetic, dielectric, photovoltaic (PV), and optical properties using Vibrating sample magnetometer, Impedance Analyzer, Fluorescence spectrophotometer, and UV Visible diffuse reflectance spectroscopy correspondingly were also explored. The effectively aimed composition (Ba0.8Zn0.2Fe2O4, Ba0.7Zn0.3Fe2O4, and Ba0.5Zn0.5Fe2O4) revealing spherical NPs and the chemical bonds were verified by Energy dispersive X-ray spectroscopy, Scanning electron microscopy, and Fourier transform infrared spectrometer individually. Znx = 0.3 sample showed maximum magnetization of 15.3 emu/g with responsive polarization. The similar sample's photocurrent increased when it was illuminated, as per photovoltaic data of current–voltage curves measured by Electrochemical impedance spectroscopy. The energy band gaps for pristine sample decreased from 1.51 to 1.35 eV for Znx = 0.3, which was closer to a theoretical optimum band gap value of about 1.4 eV for PV cells. The photoluminescence emission also lied in the visible range 607 nm. A concept for the use of magnetic NPs in PV devices was offered by valuable optical, magnetic, and photovoltaic capabilities cooperating well in the improvement of the outcome and expresses the importance of barium mono ferrite nanoparticles for aimed application. [ABSTRACT FROM AUTHOR]

In high-speed microelectronic communication, efficient and reliable radome-enclosed antenna performance is highly desired, which depends on consistent dielectric, mechanical properties, and low moisture absorption. The purpose of this study is to investigate the dielectric properties of fiber-polymer matrix composite (PMC) radome over wideband frequency and the impact of environmental aging on its performance. The dielectric constant (εr) of the SF/E0.8 (80% fiber loading) composite radome material decreased to 4% from its original value (3.93), and dielectric loss (δ) was reduced by 11% from 0.035 (2-18 GHz), while SEM morphology indicated fair interface bonding. Employing the Hallberg and Peck model, equivalent aging time (5-25 years), upon accelerated environmental aging, εr was increased up to 3.69%, δ to 9.68%, and the moisture uptake in the SF/E0.8 composite was increased from 1.13% to 1.67%, while tensile strength was retained up to 90.62% of its original value (147.83 MPa), compression strength up to 93.56% of its original value (388.54 MPa), flexural strength up to 85.44% of its original value (286.77 MPa), and interlaminar shear strength up to 77.66% of its original value (22.03 MPa), respectively. SF/E0.8 radome-enclosed antenna gain was decreased to 1%, and the voltage standing wave ratio (VSWR) was increased to 1.04% from their original values. This gradual and small deviation of SF/Ex composite properties and radome electrical performance over the extended aging time is referred to as reliable and effective for radome applications. [ABSTRACT FROM AUTHOR]

This work aims at investigating the dielectric and thermal properties of silica fiber/epoxy(SiO2/E) composite radome material subjected to 30 days of accelerated hygrothermal aging at 5 °C, 50 °C, 70 °C, and 80 °C. X-ray diffraction showed a Bragg angle (2θ) from 20° to 22.5°, while no noticeable change was observed in the morphology of SiO2/E composite radome materials, except fewer microcracks were seen (SiO2/E(5)) when exposed to 5 °C. Among the aged SiO2/E(5), SiO2/E(50), SiO2/E(70), and SiO2/E(80) composite radome material samples small variation was observed in the electrical and thermal properties except for SiO2/E(5), where the highest increment in dielectric constant (Ɛr) was noticed from 3.95 to 4.01, dielectric loss (δ) from 0.045 to 0.051, and fractional transmission was degraded 10.5% from its initial value. For SiO2/E(5) composite radome material, the maximum moisture (1.83%) was absorbed in the traverse fiber direction, while the thermal expansion coefficient (α) declined from 5.83 × 10−6 K−1 to 5.76 × 10−6 K−1, and thermal conductivity(k) dropped from 0.399 to 0.394 Wm−1K−1. However, in the SiO2/E (80) composite radome material exposed to 80 °C, the thermal conductivity was raised to 0.409 Wm−1K−1, along with less thermal degradation (23.42% weight loss) than other SiO2/E composite radome material samples exposed to 5 °C, 50 °C, and 70 °C. However, the Ɛr and δ of SiO2/E(5) (aged at 5 °C) were increased to 1.5% and 1.1.3%. It was interesting that hygrothermal accelerated aging from ambient to 80 °C did not bring any substantial change in dielectric and thermal properties of SiO2/Ex composite radome material, which reveals its sustainable performance in long-term microelectronic applications. [ABSTRACT FROM AUTHOR]

This work is aimed at studying the drug delivery applications of iron oxide (Fe3O4) nanoparticles with strontium (Sr) doping with varying molar ratios prepared by the co-precipitation route. The impact of increased strontium content on the particle size and magnetic properties was investigated. The impending of these nanoparticles for drug loading, drug release, and their respective cytotoxicity was also inspected. First, iron oxide nanoparticles were doped with various amounts of strontium, from 0.25, 0.50, and 0.75, to 1 mol using co-precipitation method. These synthesized nanoparticles were characterized by XRD, SEM, EDX, VSM, and FTIR for evaluating crystal structure, phase purity, morphology, composition, magnetic properties, and functional groups, respectively. Drug loading and drug release properties were determined using UV–vis spectroscopy, whereas MTT assay evaluated cytotoxicity. Colloidal stability was assessed using zeta potential in PBS solution. The findings confirmed the successful doping of iron oxide with strontium via XRD and EDX. SEM results confirmed spherical morphology for all and needle-like structure for 1 mol strontium doped sample. For VSM results, a single domain structure was established. It was also observed that the drug encapsulation efficiency increases with increased strontium content. Cytotoxicity results by MTT assay revealed increased cytotoxicity with increasing nanoparticle concentration, and ibuprofen-loaded nanoparticles showed higher cytotoxicity than un-loaded nanoparticles at the same concentration. Zeta potential results showed colloidal stability of iron oxide nanoparticles increased by the addition of strontium. This study provided predominantly comparison of the cytotoxicity of ibuprofen-loaded and non-loaded nanoparticles on Hep-2 cancer cells at similar concentrations for the first time for both Fe3O4 particles and Sr-doped Fe3O4 nanoparticles and enclosed the impact of increasing Sr doping content on Fe3O4 nanoparticles. [ABSTRACT FROM AUTHOR]

In many electronic applications, the dielectric and structural properties of reinforced composites are vital. In this research work, the influence of fiber proportion on the properties of a silica fiber/epoxy (SFE) composite was investigated. The structure, morphology, dielectric constant and loss factor, mechanical properties, and thermal stability were determined. The increase of wt.% of silica fiber (SiO2 (f)) x = 30 to 90, reduced the dielectric constant (εr) and dielectric loss (δ) of the SFE composite from their original values to 18.9% and 48.5%, lowering local charge displacement towards the applied electric field. The SFE composite showed higher mechanical properties with the increase in SiO2 (f), x = 30 to 80, the tensile strength (UTS) was raised from 91.6 MPa to 155.7 MPa, the compression strength (UCS) was increased from 261.1 MPa to 409.6 MPa and the flexural strength was enhanced from 192.3 MPa to 311.9 MPa. Upon further addition of SiO2 (f) to the composite, i.e., x = 90, the mechanical properties were reduced a little, but the dielectric properties were not changed. Increasing SiO2 (f) improved the thermal stability as weight loss was found to be 69% (x = 30) and 24% (x = 90), and average moisture absorption was found to be 1.1 to 1.8%. A silica fiber/epoxy composite, for microelectronics, can be made from a low-cost fiber, and its dielectric properties as well as its mechanical and thermal stability can be tuned or improved by varying fiber fractions. [ABSTRACT FROM AUTHOR]

Polymer matrix wave transparent composites are used in a variety of high-speed communication applications. One of the applications of these involves making protective enclosures for antennas of microwave towers, air vehicles, weather radars, and underwater communication devices. Material performance, structural, thermal, and mechanical degradation are matters of concern as advanced wireless communication needs robust materials for radomes that can withstand mechanical and thermal stresses. These polymer composite radomes are installed externally on antennas and are exposed directly to ambient as well as severe conditions. In this research, epoxy resin was reinforced with a small amount of quartz fibers to yield an improved composite radome material compared to a pure epoxy composite with better thermal and mechanical properties. FTIR spectra, SEM morphology, dielectric constant (Ɛr) and dielectric loss (δ), thermal degradation (weight loss), and mechanical properties were determined. Compared to pure epoxy, the lowest values of Ɛr and δ were 3.26 and 0.021 with 30 wt.% quartz fibers in the composite, while 40% less weight loss was observed which shows its better thermal stability. The mechanical characteristics encompassing tensile and bending strength were improved by 42.8% and 48.3%. In high-speed communication applications, compared to a pure epoxy composite, adding only a small quantity of quartz fiber can improve the composite material's dielectric performance, durability, and thermal and mechanical strength. [ABSTRACT FROM AUTHOR]

Supercapacitors, also known as electrochemical capacitors, store energy either by the adsorption of ions (electric double-layer capacitors) or by fast redox reactions at the surface (pseudocapacitors). When high power delivery or uptake is required in electrical energy storage and harvesting applications, they can complement or replace batteries. The fundamental and applied aspects of supercapacitors have seen rapid progress in recent years. With the development of advanced nanostructured materials and a better understanding of charge storage mechanisms, significant performance improvements have been achieved. In this review, the latest advances in supercapacitors in charge storage mechanisms and electrode materials is discussed. We describe the working principle and challenges of different advanced materials used as supercapacitor electrodes and strategies to overcome these challenges. The focus is on materials like metal sulfides, metal oxides, conducting polymers, MXenes, metal–organic frameworks, and covalent organic frameworks. The performance of electrode materials is analyzed by parameters including energy density, capacitance, power density, cyclic stability, and rate capability. The prospects and challenges related to supercapacitors in applied applications are also discussed. [ABSTRACT FROM AUTHOR]

An essential challenge faced by pseudocapacitive electrode materials is insufficient charge storage capability with high intrinsic electrical resistance and structural instability. With an exponential increase in the demand for a pollutant-free environment, ternary metal compounds are being extensively explored as an attractive solution to these problems. Herein, we have addressed a solution to the above-listed issues by synthesizing novel and binder-free NiMnCo layered double hydroxide (NiMnCo-LDH) nanosheets on Fe-substituted NiCo2O4 (FexNi1−xCo2O4) nanorods supported on nickel foam via a facile hydrothermal method followed by chemical bath deposition. The highly defined and well-distributed porous Fe-substituted NiCo2O4 nanorod structure integrated with the ternary NiMnCo-LDH nanosheets provide ultra-fast kinetics of charge transfer, increased charge storage capacity, and high structural stability. The nanocomposite electrode delivers a high specific capacity of 281 mAh/g at a scan rate of 5 mV/s (265 mAh/g at 1 A/g) with a capacitance retention of 92% after 5000 cycles at 2 A/g. The effect of Fe in NiCo2O4 is further validated by performing density-functional theory (DFT) calculations to obtain atomic insights on electrical conductivity using the density of states (DOS) and band structures. Finally, a symmetric supercapacitor based on FexNi1−xCo2O4@NiMnCo LDH was assembled which delivered an impressive energy density of 105 Wh/kg and a power density of 1112 W/kg, proving FexNi1−xCo2O4@NiMnCo-LDH as an electrode material to be used for applications of energy storage. [ABSTRACT FROM AUTHOR]

For curing of fiber-reinforced epoxy composites, an alternative to thermal heating is the use of microwave energy, which cures quickly and consumes less energy. Employing thermal curing (TC) and microwave (MC) curing methods, we present a comparative study on the functional characteristics of fiber-reinforced composite for microelectronics. The composite prepregs, prepared from commercial silica fiber fabric/epoxy resin, were separately cured via thermal and microwave energy under curing conditions (temperature/time). The dielectric, structural, morphological, thermal, and mechanical properties of composite materials were investigated. Microwave cured composite showed a 1% lower dielectric constant, 21.5% lower dielectric loss factor, and 2.6% lower weight loss, than thermally cured one. Furthermore, the dynamic mechanical analysis (DMA) revealed a 20% increase in the storage and loss modulus along with a 15.5% increase in the glass transition temperature (Tg) of microwave-cured compared to thermally cured composite. The fourier transformation infrared spectroscopy (FTIR) showed similar spectra of both the composites; however, the microwave-cured composite exhibited higher tensile (15.4%), and compression strength (4.3%) than the thermally cured composite. These results illustrate that microwave-cured silica-fiber-reinforced composite exhibit superior electrical performance, thermal stability, and mechanical properties compared to thermally cured silica fiber/epoxy composite in a shorter time and the expense of less energy. [ABSTRACT FROM AUTHOR]

Barium mono-ferrite (BaFe2O4) and barium hexa-ferrite (BaFe12O19) nanoparticles were produced by the sol–gel auto-combustion method. The prepared nanoparticles were examined by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy (RAMAN), and Scanning electron microscopy (SEM) for structural, functional, and vibrational bonding, and morphological study, respectively. The optical, dielectric, and magnetic characteristics were explored by UV–visible spectroscopy, Fluorescence spectrophotometer, Impedance analyzer, and Vibrating sample magnetometer (VSM). The ferroelectric nature of magnetic nanoparticles was confirmed by the Multi-ferroic system. Electrochemical impedance spectroscopy monitored electrical properties by current–voltage (I–V) curves. The structure of BaFe2O4 was orthorhombic having space group Pnma 3 while BaFe12O19 was identified as hexagonal with space group P63/mmc (194). FTIR and Raman spectrum identified chemical structural bonds. SEM micrographs revealed the distinct size of nanoparticles. Saturation magnetization (Ms) for BaFe12O19 was 25.88 emu/g with a coercivity (Hc) value of 9668.05 and greater than BaFe2O4 with 1.4 emu/g and 2038. Di-electric properties of BaFe12O19 were higher than BaFe2O4 and not considered encouraging for photovoltaic applications. BaFe2O4 indicated balanced absorbance (1.03%) in the UV–visible region with 1.51 eV direct band gap that justified the main characteristics of a PV material. BaFe12O19 possessed high absorbance (37%) in the UV region with an indirect band gap of 1.24 eV that not believed as a viable choice for PV functioning. The fluorescence emission spectrum resulted higher concentration of 106 for BaFe12O19 while 51.3 for BaFe2O4 in the visible region. The highly concentrated materials could damage PV module by triggering hot spot. The I–V curves unveiled BaFe2O4 more respondents to dark and photo-current while BaFe12O19 possessed a negligible response. Above-stated results established that BaFe2O4 is comparatively a novel nano-ferrite that comprises more supportive properties for photovoltaic applications than BaFe12O19. [ABSTRACT FROM AUTHOR]

Polystyrene (PS)/sepiolite clay nanocomposites were prepared via the melt extrusion technique using vinyl tri-ethoxy silane (VTES) as the compatibilizer and cross-linking agent. Mechanical, thermal, and flame-retardant properties of the newly developed polystyrene-based nanocomposites were determined. Surface morphology was investigated using scanning electron microscopy (SEM), examining the distribution of the filler in various compositions of fabricated composites. Structural analysis of the samples was carried out using the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. Thermal stability was determined by thermal gravimetric analysis (TGA), showing a maximum 30.2 wt.% increase in residue by adding sepiolite clay. The results obtained from the dynamic mechanical analyzer (DMA) in terms of the storage modulus, loss modulus and damping factor exhibited better stress transfer rate and effective interfacial adhesion between the filler and the matrix. The higher filler loaded sample showed greater flame retardancy by decreasing the burning rate up to 48%. [ABSTRACT FROM AUTHOR]

A one-step thermo-chemical approach was employed to synthesize ZnFe2O4/rGO nanohybrids with increasing GO concentrations (0, 10, 20, and 30 wt. %). This approach was used to reduce GO while simultaneously synthesizing ZnFe2O4 nanoparticles and adhering them to rGO sheets. The nanohybrids were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and impedance analyzer. The XRD patterns confirmed the formation of a face-centered cubic single phase of ZnFe2O4/rGO nanohybrid and SEM images revealed the decoration of ZnFe2O4/rGO nanoparticles on rGO sheets. The dielectric properties improved as GO loadings increased. At 100 Hz, the dielectric constant and dielectric loss increased to 2.04 × 104 and 1.20 × 105 for ZnFe2O4/rGO nanohybrid with 30 wt. % of GO when compared to pure ZnFe2O4 of 4.23 × 102 and 1.92 × 103, respectively. The feasibility of this method implies that this nanohybrid can be used for charge storage devices. [ABSTRACT FROM AUTHOR]

In the current work cobalt, magnesium and lithium dopant substitution is performed in series of SrFe(12-2x)(Co,Mg,Li)xO19 (for x = 0.0, 0.15, 0.25, 0.5) using sol–gel method. The prepared samples were calcined at 950 °C for 4h. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). LCR meter was used for performing dielectric measurements. The formation of hexagonal SrFe(12-2x)(Co,Mg,Li)xO19 was confirmed using XRD. Debye Scherer was used to determining the crystallite size in the range of 37–57 nm. The band positions were studied using FTIR. The real part of the dielectric constant enhanced to 77.8 at 250 Hz for x = 0.5. The value of dielectric loss for cobalt, magnesium, and lithium-doped strontium hexaferrite nanoparticles has increased from 2.21 to 54.0 at 250 Hz. AC conductivity values also showed an increase as the concentration increased in strontium hexaferrite. AC conductivity results explain that electron hopping governs the conduction process. The electrical properties and conductivity rise with the increasing concentration of dopant. The enhanced dielectric properties and increased conductivity of the prepared nanoparticles make it applicable in supercapacitors and charge storage devices. [ABSTRACT FROM AUTHOR]

Transition metals are attracting numerous interests for their substantial applications in supercapacitors and as non-noble metal electrocatalyst for overall water splitting. Herein, the NiMn layer double hydroxide (NiMn-LDH) is developed using the sonochemical route at different reaction times, which act as a multifunctional electrode for supercapacitors and overall water splitting. The capacitance of layer double hydroxide (LDH) synthesized at 4 h (NiMn-LDH-4 h) of reaction time was found to be 527 F g−1 at 1 A g−1, with 91.2% capacitance retention after 5,000 cycles at 2 A g−1 in 6 M KOH. For hydrogen and oxygen evolution reactions, the NiMn-LDH-4 h electrode exhibits a standard of 10 mA cm−2 at an overpotential of 120 mV and 296 mV, respectively, in 1 M KOH. Moreover, fabricated NiMn-LDH-4 h||NiMn-LDH-4 h electrolyzer for overall water splitting benchmarks 10 mA cm−2 at 1.6 V. The superior electrochemical properties of the NiMn-LDH electrodes might be attributed to quick diffusion paths and enhanced redox reaction of NiMn-LDH nanosheets because of the high surface area. [ABSTRACT FROM AUTHOR]

In this reported study, magnesium-substituted cobalt ferrite nanoparticles (Co1−xMgxFe2O4, x = 0.0, 0.20, 0.35, 0.50) have been investigated. The samples were prepared via a wet chemical co-precipitation route and were calcinated at 800 °C for 6 h. The structural, electrical, and dielectric properties of these samples were studied using XRD, SEM, FTIR, impedance analyzer, and LCR meter. The XRD diffractograms established the development of FCC spinel arrangement with decreasing crystallite size from 20 to 30 nm without any additional impurity peak confirming the purity of the samples synthesized. The FTIR spectra established the existence of tetrahedral (A) and octahedral (B) lattice sites in the structural arrangement. The SEM images showed uniform nano-spherical particle formation with minimum porosity. No extra phase or impurity was found, confirming the effectiveness of the co-precipitation route. The dielectric properties of the synthesized samples measured at ambiance temperature against frequency range of 103 Hz to 5 MHz showed massive enhancement of dielectric constant (on the order of 104 at 100 Hz) which was comparable to traditional ceramics (having a dielectric constant in the range of 104–106), which are often rendered suitable for capacitor applications. Furthermore, the low values of dielectric loss tangent at high frequencies verified its potential usage in microwave applications. A significant contribution of both long- and short-range order in hopping as well as an increase in grain boundary density was confirmed by complex electric modulus analysis. The DC electrical resistivity measurement against increasing temperatures was done, showing a typical decreasing trend with increasing temperature, validating the semiconductor nature of synthesized nanoparticles with varying compositions. The drift mobility was further calculated from the DC resistivity data. [ABSTRACT FROM AUTHOR]

To achieve the suitable set of synergistic mechanical, dielectric, and electromagnetic interference shielding properties, polymer blends based on varying the concentration of conductive polymer polyaniline (PANI) in insulative matrix of polyvinyl alcohol (PVA) as well as hybrid composites by adding few layer graphene (FLG) in PVA/PANI polymer blends are prepared using solution casting method. In PVA/PANI blends, by increasing the concentration of PANI, dielectric constant (ε′), dielectric loss (ε″), and total shielding efficiency (SET) of PVA are enhanced from 4 to 80, 0.72 to 164, and 2.5 to 30 dB at 100 Hz, respectively, at the considerable loss of its mechanical properties particularly the tensile strength from 23.9 to 8.5 MPa. For hybrid composites of PVA/PANI/FLG, mechanical as well as dielectric and EMI shielding properties are remarkably enhanced at very low loading levels of FLG. The incorporation of small amounts of FLG in PVA/PANI‐10 wt%, the ε′, ε″, and SET are increased from 4 to 7,907, 0.5 to 406,947.5 and 2.5 to 99 dB at 100 Hz, respectively, along with the considerable increase in the mechanical properties such as tensile strength from 15.7 to 36.3 MPa and modulus from 0.1 to 0.96 GPa at the loss of strain. In comparison to PVA/PANI blends, hybrid composites of PVA/PANI/FLG become a promising system for microwave absorption applications. POLYM. COMPOS., 39:3686–3695, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The reinforcement tendency of acrylonitrile butadiene styrene/single‐walled carbon nanotubes hybrid composites is investigated using universal tensile testing machine. SWCNT are exfoliated in the ABS matrix at all concentrations, however, selective localization of SWCNT occurred in the SAN phase rather than the PB phase of ABS. Although, glass transition temperature of ABS remained intact by the incorporation of SWCNTs, but mechanical properties are enhanced significantly. The increase in tensile strength and Young's modulus of ABS/SWCNT hybrid composites is up to 48% and 103%, respectively, at considerable loss of strain at break inferring the restriction in the movement of the ABS chains by anchoring them in the vicinity of SWCNT. Modified rule of mixture (MRoM) model is employed to predict the rate of increase in the Young's modulus (dY/dVf) of ABS/SWCNT hybrid composites. The predicted trends are correlated well with the experimental values of dY/dVf in the lower volume fraction of SWCNT in ABS demonstrating the effective load transfer from the polymer matrix to the nanotubes. POLYM. COMPOS., 39:E902–E908, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The magnetic nanoparticle composite NiFe2O4 has traditionally been studied for high-frequency microwave absorption with marginal performance towards low-frequency radar bands (particularly L and S bands). Here, NiFe2O4 nanoparticles and nanohybrids using large-diameter graphene oxide (GO) sheets are prepared via solvothermal synthesis for low-frequency wide bandwidth shielding (L and S radar bands). The synthesized materials were characterized using XRD, SEM, FTIR and microwave magneto dielectric spectroscopy. The dimension of these solvothermally synthesized pristine particles and hybrids lies within 30–58 nm. Microwave magneto-dielectric spectroscopy was performed in the low-frequency region in the 1 MHz-3 GHz spectrum. The as-synthesized pristine nanoparticles and hybrids were found to be highly absorbing for microwaves throughout the L and S radar bands (< −10 dB from 1 MHz to 3 GHz). This excellent microwave absorbing property induced by graphene sheet coupling shows application of these materials with absorption bandwidth which is tailored such that these could be used for low frequency. Previously, these were used for high frequency absorptions (typically > 4 GHz) with limited selective bandwidth. [ABSTRACT FROM AUTHOR]

To predict the thermal conductivity of granite rocks the existing mixing law and empirical models have been utilized. Due to the porosity dependence in all the existing models, ASTM standard methods have been utilized to measure the porosity including specific gravity and density. The chemical composition of these samples has been analysed using the x-ray fluorescence technique. Because of the complex structure of the specimens and non-availability of data, models depending on the strict geometrical structure like the shape, size, position of the constituent mineral and the arrangement of fluid in the samples have not been used. The predicted values of the effective thermal conductivity have been compared with the experimental measurements made on the samples, using Gustafsson's probe. The calculated thermal conductivities from various models are in agreement with the experimental observations. Simple correlations between the chemical composition and specific gravity, density and porosity are also reported. [ABSTRACT FROM AUTHOR]

The thermal conductivity, thermal diffusivity and heat capacity per unit volume of granite samples taken from the Shewa–Shahbaz Garhi volcanic complex near Mardan, Pakistan have been measured simultaneously using the transient plane source technique. The temperature dependence of the transport properties was studied in the temperature range 253–333 K. Different relationships for the temperature dependence of thermal conductivity and thermal diffusivity were tested. The samples are also characterized by the chemical composition, density, porosity and specific gravity at room temperature and normal pressure. The theoretical calculation of the specific gravity parameter based on the chemical composition was in good agreement with that obtained from experimental observation. No correlation was found between the temperature dependence of the thermal transport behaviour on porosity, chemical composition and density. [ABSTRACT FROM AUTHOR]

The thermal conductivity, thermal diffusivity and volumetric heat capacity of monocrystalline AgCl were measured simultaneously, using the Gustafsson probe in the temperature range 77–300 K. The thermal conductivity, as well as the thermal diffusivity, of these crystals follows a T-1 behaviour in the temperature region mentioned here. The heat capacity at constant pressure (CP), determined from the volumetric heat capacity, agrees with the calculated one at room temperature. The values of CP obtained from this experiment along with the reported data as a function of temperature are also reported. [ABSTRACT FROM AUTHOR]