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This work studied the sustainable approach for the development of bio‐based polybenzoxazine composites derived from sustainable thymol and utilized for diverse applications viz., superhydrophobic, high dielectric, and resistant to bacterial corrosion. The molecular structure of benzoxazines was ascertained from spectral analyses and curing behavior was assessed using differential scanning calorimetry (DSC) analysis. The benzoxazines were polymerized through ring‐opening polymerization to assess their thermal stability using TGA. Among the synthesized polybenzoxazines, the poly(BT‐fa) developed using bis‐thymol (BT) and furfurylamine (fa) which possesses the furfural core contributes to higher thermal stability with the enhanced value of char yield of 43%. Thus, poly(BT‐fa) was chosen for the preparation of composites, and found that 15 wt% chicken feather carbon (CFC) and 15 wt% cashew nutshell cake carbon (CSC) used as reinforcements exhibit significantly enhanced decomposition temperature with char yield of 77% and 69% respectively. Dielectric performance of the composites with high k values of 7.66 and 8.66 was obtained for 15 wt% of the CFC and CSC bio‐carbon reinforcements respectively. These bio‐based benzoxazines also exhibited substantial antibacterial activity, indicating their potential utility toward resistance against microbial colonization. Among polybenzoxazines, poly(BT‐sa) exhibits the highest value of water contact angle (WCA) of 151°. To exploit the superhydrophobic properties of polybenzoxazines, the cotton fabrics were coated with poly(BT‐sa). It was found that poly(BT‐sa) coated cotton fabric possesses an excellent WCA value of 161°, which indicates its suitability for self‐cleaning and water‐repellent applications. Further, poly(BT‐oa) possesses enhanced anti‐corrosion‐resistant behavior than that of other polybenzoxazines and contributes to better protection of mild steel surfaces from corrosion. The values of tensile modulus /flexural modulus and tensile strength and flexural strength obtained for poly(BT‐fa) are 5.1/3.7 GPa and 66 ± 1/103 ± 1 MPa, respectively. Data obtained for bi‐functional bio‐based polybenzoxazine composites from different studies suggest that these materials can be used in antimicrobial, superhydrophobic, and corrosion‐resistant applications. [ABSTRACT FROM AUTHOR]

As the competition intensifies in enhancing the integration and performance of integrated circuits, in accordance with the famous Moore's Law, higher performance and smaller size requirements are imposed on the dielectric layers in electronic devices. Compared to vacuum methods, the production cost of preparing dielectric layers via solution methods is lower, and the preparation cycle is shorter. This paper utilizes a low-temperature self-exothermic reaction based on the solution method to prepare high-performance Al2O3 dielectric thin films that are compatible with flexible substrates. In this paper, we first established two non-self-exothermic systems: one with pure aluminum nitrate and one with pure aluminum acetylacetonate. Additionally, we set up one self-exothermic system where aluminum nitrate and aluminum acetylacetonate were mixed in a 1:1 ratio. Tests revealed that the leakage current density and dielectric constant of the self-exothermic system devices were significantly optimized compared to the two non-self-exothermic system devices, indicating that the self-exothermic reaction can effectively improve the quality of the dielectric film. This paper further established two self-exothermic systems with aluminum nitrate and aluminum acetylacetonate mixed in 2:1 and 1:2 ratios, respectively, for comparison. The results indicate that as the proportion of aluminum nitrate increases, the overall dielectric performance of the devices improves. The best overall performance occurs when aluminum nitrate and aluminum acetylacetonate are mixed in a ratio of 2:1: The film surface is smooth without cracks; the surface roughness is 0.747 ± 0.045 nm; the visible light transmittance reaches up to 98%; on the basis of this film, MIM devices were fabricated, with tested leakage current density as low as 1.08 × 10−8 A/cm2 @1 MV and a relative dielectric constant as high as 8.61 ± 0.06, demonstrating excellent electrical performance. [ABSTRACT FROM AUTHOR]

Advancements in power electronics necessitate dielectric polymer films capable of operating at high temperatures and possessing high energy density. Although significant strides have been achieved by integrating inorganic fillers into high-temperature polymer matrices, the inherently low dielectric constants of these matrices have tempered the magnitude of success. In this work, we report an innovative nanocomposite based on sulfonylated polyimide (SPI), distinguished by the incorporation of sulfonyl groups within the SPI backbone and the inclusion of wide bandgap hafnium dioxide (HfO2) nanofillers. The nanocomposite has demonstrated notable enhancements in thermal stability, dielectric properties, and capacitive performance at elevated temperatures. Detailed simulations at both molecular and mesoscopic levels have elucidated the mechanisms behind these improvements, which could be attributed to confined segmental motion, an optimized electronic band structure, and a diminished incidence of dielectric breakdown ascribed to the presence of sulfonyl groups. Remarkably, the SPI-HfO2 nanocomposite demonstrates a high charge-discharge efficiency of 95.7% at an elevated temperature of 150 °C and an applied electric field of 200 MV/m. Furthermore, it achieves a maximum discharged energy density of 2.71 J/cm3, signalling its substantial potential for energy storage applications under extreme conditions. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are used to prepare polymer composites with a high dielectric constant. However, a high leakage conductance is undesirable. Herein, amorphous carbon spheres were used to replace single-walled CNTs (SWCNTs) to fabricate polyvinyl chloride (PVC) composites. Two sets of composite films, marked with PVC/SWCNT and PVC/carbon sphere, were prepared. Dielectric, conductive and breakdown traits of composites were determined. PVC/carbon sphere composites display more advantageous properties than PVC/SWCNT composites. Unlike SWCNTs, carbon spheres exhibit a mild interface polarization with PVC and no percolation, resulting in balanced electric properties of composites including a rationally increased dielectric constant, greatly reduced dielectric loss and significantly improved breakdown strength. The optimal PVC composite with 12 wt% carbon spheres has a dielectric constant of ~ 186, dielectric loss of ~ 0.19 at 100 Hz, and breakdown strength of ~ 333 MV m−1. This work boosts a large-scale fabrication of outstanding composites used in modern capacitors. [ABSTRACT FROM AUTHOR]

A systematic evaluation of deploying Ga x Ce y O z passivation layer (PL) on Si substrate subjected to postdeposition annealing in forming gas-oxygen-forming gas ambient at different temperatures (600–900 °C) was carried out. The inclusion of hydrogen and/or nitrogen ions, in addition to their attachment to oxygen vacancies and Si dangling bonds, has been reported. The attachment became more prominent at 600 and 700 °C while oppositely, the incoming oxygen ions acquired adequate energy to break the attachment at/beyond 800 °C. Therefore, it is conceivable that the Ga x Ce y O z PL annealed at/beyond 800 °C have attained a thicker interfacial layer (IL). The acquisition of a higher N ss has been attributed to the de-passivation of Si dangling bonds by the excessive hydrogen ions present at the interface. The potential of utilizing Ga x Ce y O z PL annealed at 700 °C as a PL for metal-oxide-semiconductor applications was inferred through a thorough electrical analysis conducted in this work. [ABSTRACT FROM AUTHOR]

Polycrystalline multicomponent garnets (Y0.2Gd0.2Er0.2Eu0.2Dy0.2)3Fe5O12 were obtained by glycine-nitrate pyrolysis and coprecipitation (termed (Y,Ln)IG_pyr and (Y,Ln)IG_cop, respectively). They were analyzed by XRD, SEM, microprobe analysis, diffusion reflectance, Raman, and impedance spectroscopy. Properties of multicomponent garnets were compared with those of single-component garnets Me3Fe5O12 (Me = Y, Eu, Gd, Dy, Er) obtained by glycine-nitrate pyrolysis. Structural analysis confirmed the predominant content of the garnet phase; the Rietveld method for (Y,Ln)IG_pyr garnet revealed six different types of Fe octahedra. Elemental mapping of garnets demonstrated that Y, Eu, Er, Gd, Dy, Fe distribution in (Y,Ln)IG_pyr was more uniform than in (Y,Ln)IG_cop. The optical spectra revealed charge transfer bands O2− → Fe3+ and d-d transitions of VIFe3+ and IVFe3+ions; the band gaps were 2.45 eV and 2.42 eV for YIG and (Y,Ln)IG_pyr, respectively. Raman spectra of garnets were analyzed using a statistical approach based on the autocorrelation function and the associated parameter Δcorr; sufficient distortion of Y(Ln)O8 polyhedra has been noted in multicomponent garnet. The equivalent circuit method was used to process the impedance spectra. The electrical conductivity of single-component garnets was lower than that of multicomponent ones. The activation energy of garnet (Y,Ln)IG_pyr conductivity E a in the temperature range 200 ÷ 625 and 625 ÷ 900 °C was 0.66 eV and 0.98 eV, respectively, which was lower than that of single-component garnets. The values of dielectric constants for (Y,Ln)IG_pyr and (Y,Ln)IG_cop (ꜫ' = 364.3 and 252.9 at 300 °C at 300 kHz) were higher than those for YIG, GdIG, ErIG, EuIG, DyIG garnets (91.5, 42.4, 232.5, 21.1, 36.2, respectively). [ABSTRACT FROM AUTHOR]

To alleviate the environmental hazard and minimize the practice of utilizing fossil fuel‐based precursors in the production of benzoxazines, sustainable bio‐phenol precursors namely magnolol and bio‐based amine furan‐2yl‐methanamine have been utilized to synthesize bio‐benzoxazine and was cured and characterized. The curing temperature of the synthesized bio‐benzoxazine monomer was found to be 216°C. Utilizing the carbon obtained from two different bio‐sources namely, chicken feather and cashew nut shell cake bio‐polybenzoxazine composites were prepared. The char yield of bio‐carbon reinforced bio‐polybenzoxazine composites was enhanced to 65% compared to that of neat polybenzoxazine (60%). The value of the dielectric constant of neat polybenzoxazine was found to be 5.52 which was further improved to a maximum of 8.9 and 7.8 on reinforcement of 15 wt% chicken feather carbon and 15 wt% cashew nut shell cake carbon respectively. The prepared bio‐polybenzoxazine composites exhibit a near superhydrophobic nature with the value of water repulsive angle at 150° than that of neat matrix (143°). From the obtained results, it is suggested that the sustainable bio‐carbon reinforced bio‐based benzoxazine will be a promising material for thermally stable, high dielectric, and water‐repellent applications. Highlights: Eco‐friendly, sustainable magnolol‐based bio‐benzoxazine was synthesized.Waste valorization for bio‐carbon—poultry, and agricultural wastes were utilized.Bio‐carbon reinforcement marginally increases the thermal stability of composites.Bio‐carbon reinforced composites exhibit close to superhydrophobic nature.Incorporation of bio‐carbon enhances the value of dielectric constant. [ABSTRACT FROM AUTHOR]

To achieve all-organic polymer with high dielectric performances, we have designed a novel side-chain liquid crystalline polymer (P7) with strong polar mesogen of (Z)-4-(2-cyano-2-phenylvinyl)benzonitrile (CSCN) attached to polycyclooctene backbone. The bis-cyano-substituted CSCN is board-shaped and exhibits a large dipole moment (8.54 D) which tilts ∼34.2° away from its molecular long axis. Consequently, CSCN shows unique dual molecular anisotropy: one from biaxial shape anisotropy and the other from polarization anisotropy. The complex phase behaviors of P7 were investigated employing mainly the techniques of differential scanning calorimetry and X-ray diffraction. Four liquid crystal (LC) phases are identified as K0, K1, K2 and K3, which are SmA, highly-ordered biaxial SmA, B5-like and B7-like, respectively, with the thermal stability increased in sequence. The experimental results indicate that the different LC phases are arisen from the competition and balance between π-π stacking and dipole-dipole interaction. While the face-to-face π-π stacking is dominant in K0 and K1, optimizing the dipole-dipole interaction causes the CSCN mesogens within the smectic layer to tilt and rotate, resulting in K2 and K3. We further investigated the dielectric properties of P7 films using polarization-electric field loops test. The dielectric constant (εr) of P7 is found to be LC structure dependent, which is increased when the LC phase is varied from K0 to K3. With an average εr of 9.7 achieved in K3 and the low dielectric loss (tan δ = 0.001), P7 film offers a promising material in advanced applications like energy storage and electronic devices.

While efforts have been made to optimize organic semiconducting materials to achieve low-power-consumption organic field-effect transistors (OFETs), it is important to note that the choice of gate dielectric materials is equally critical. In general, a high-k polymer dielectric material is highly preferred for low-power-consumption OFETs. In this perspective, we highlight several newly emerged strategies for high dielectric constant polymer dielectrics. By exploiting the recent advances in molecular modulation and morphology control, these new strategies enable remarkably high dielectric constant up to 25–30 for polymer dielectrics, while still maintaining dielectric losses below 0.01 at 1 kHz. We further analyze the advantages and disadvantages of these strategies and propose four design principles—side-chain dipole, rigid free volume, self-assembly, and thermosets—for future polymer gate dielectrics in OFETs. [ABSTRACT FROM AUTHOR]

(Al–Hf) mixed oxide thin films (HfAlO) are attracted by many researchers because of their outstanding optical and electrical properties compared to hafnium oxide (HfO 2). This study prepared HfAlO films at 300 °C using plasma-enhanced atomic layer deposition (PEALD). Changing the cycle ratio of HfO 2 and aluminum oxide (Al 2 O 3), the mixing effect on the properties of HfAlO film was studied. The characterization of the HfAlO films was investigated using spectroscopic ellipsometry (SE), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), scanning electron microscopy (SEM), and UV–vis spectroscopy. The results show that the aluminum content and optical bandgap of the HfAlO films increased with the increase of the Al 2 O 3 cycle ratio. The dielectric constant of the HfAlO film with a 20 % Al 2 O 3 cycle ratio (cycles of Al 2 O 3 /(cycles of Al 2 O 3 + cycles of HfO 2)) reaches ∼ 26, and the breakdown electric field is about 6.5 MV/cm. Pure HfO 2 and 20 % Al 2 O 3 cycle ratio deposited HfAlO was used as the gate dielectric layer, and the influence on the performance of amorphous indium gallium zinc oxide (a-IGZO) thin film transistor (TFT) was studied. A-IGZO TFT with a 20 % Al 2 O 3 cycle ratio mixed HfAlO film as the gate dielectric exhibits the best performance, showing a high I on /I off ratio of 1.3 × 109, a saturation mobility of ∼5.8 cm2/Vs, a subthreshold slope of 88 mV per decade and a low threshold voltage of −0.1V. [ABSTRACT FROM AUTHOR]

We have developed a method for designing polymer and graphene nanoplatelet (GNP) composites that show high dielectric constants over a wide range of GNP contents. GNPs are dispersed in the composites through plasma-surface modification and aligned by applying an electric field (EF). This creates a large number of microcapacitor structures of GNPs separated by the polymer. The maximum dielectric constant of the sample to which the EF is applied is approximately twice that of the sample to which the EF is not applied. Furthermore, the maximum dielectric constants of the samples with plasma-surface modified GNPs are higher than those of the samples with unmodified GNPs. The composites show high dielectric constants (∼500 at 100 Hz) over a wide range of GNP contents (6 ∼ 10 wt%) while maintaining mechanical flexibility (Young’s modulus:12 ± 4 MPa).

As the competition intensifies in enhancing the integration and performance of integrated circuits, in accordance with the famous Moore’s Law, higher performance and smaller size requirements are imposed on the dielectric layers in electronic devices. Compared to vacuum methods, the production cost of preparing dielectric layers via solution methods is lower, and the preparation cycle is shorter. This paper utilizes a low-temperature self-exothermic reaction based on the solution method to prepare high-performance Al2O3 dielectric thin films that are compatible with flexible substrates. In this paper, we first established two non-self-exothermic systems: one with pure aluminum nitrate and one with pure aluminum acetylacetonate. Additionally, we set up one self-exothermic system where aluminum nitrate and aluminum acetylacetonate were mixed in a 1:1 ratio. Tests revealed that the leakage current density and dielectric constant of the self-exothermic system devices were significantly optimized compared to the two non-self-exothermic system devices, indicating that the self-exothermic reaction can effectively improve the quality of the dielectric film. This paper further established two self-exothermic systems with aluminum nitrate and aluminum acetylacetonate mixed in 2:1 and 1:2 ratios, respectively, for comparison. The results indicate that as the proportion of aluminum nitrate increases, the overall dielectric performance of the devices improves. The best overall performance occurs when aluminum nitrate and aluminum acetylacetonate are mixed in a ratio of 2:1: The film surface is smooth without cracks; the surface roughness is 0.747 ± 0.045 nm; the visible light transmittance reaches up to 98%; on the basis of this film, MIM devices were fabricated, with tested leakage current density as low as 1.08 × 10−8 A/cm2 @1 MV and a relative dielectric constant as high as 8.61 ± 0.06, demonstrating excellent electrical performance.

Herein, bismuth–yttrium iron garnet (Bi-YIG) doped with In3+ ions with chemical formula Y2BiInxFe5−xO12 (x = 0.00–0.75 in steps of 0.15) was successfully prepared using solid-state reaction method. Effects of In3+-ion doping on microstructural, magnetic, and dielectric properties of Bi-YIG ferrite are investigated and discussed. Results show that In doping does not change the phase of Bi-YIG ferrite but increases lattice constant. Microstructure analysis indicates that In doping not only results in uniform grain shape but also influences grain size (the maximum average size is 3.46 μm at x = 0.30). Vibrating sample magnetometry results reveal that upon increasing In3+-ion content from x = 0.00 to x = 0.75, saturation magnetization first increases from 14.48 to 24.71 emu/g (at x = 0.45) and then decreases to 15.43 emu/g (at x = 0.75). Ferromagnetic resonance linewidth first decreases from 538.5 to 384.7 Oe (at x = 0.30) and then increases to 416.5 Oe (at x = 0.75). Real part of the permeability increases from 17.1 (x = 0.00) to 21.2 (x = 0.45) and then decreases to 19.5 (x = 0.75) in frequency range from 1 MHz to 1 GHz. Additionally, In doping leads to the dielectric constant reaching a maximum value of ε' = 20.4 at x = 0.15, while maintaining low dielectric loss of ~ 10−4 at the frequency of 10 GHz. Prepared material can be employed in high-frequency circulators, isolators, and microwave devices. [ABSTRACT FROM AUTHOR]

In recent years, self-power sensing systems based on triboelectric nanogenerators (TENGs) have been extensively studied. However, pure polymer friction materials are not satisfactory in terms of their triboelectric properties and cannot meet the needs of high-performance TENGs. We have improved the performance of a polymer electrode-based TENG by increasing the specific surface area of the material as well as the dielectric constant of the triboelectric layer. Benefitting from the enhanced dielectric constant engineering and high surface area engineering, the BaTiO3@CMC-based TENG exhibits excellent output performance which is 3 times higher than that of a pure CMC-based TENG. As expected, the obtained self-powered TENG can be used to monitor the wind speed with a high sensitivity of 1.97 V/(m s−1). In addition, the obtained sensor system can accurately map the contact position and touch trajectory of the object when assembling the TENG with a 4 × 4 array on an acrylic substrate. This work will provide basic insights into improving the performance of TENGs and widen their applications in the field of sensing. [ABSTRACT FROM AUTHOR]

The comprehensive control of dielectric properties and temperature stability is the focus of BaTiO 3 -based ceramics with non-reducibility. For this purpose, BaTiO 3 –0.02MgO–0.02Y 2 O 3 –0.04CaZrO 3 –xMnO 2 (x = 0, 0.005, 0.01 and 0.015) ceramics were prepared by the solid-state method and sintered in a reducing atmosphere. When x = 1.5 mol%, high dielectric constant (ԑ r ∼ 3644), large insulation resistivity (ρ v ∼ 2.07 × 1011 Ω cm), and low dielectric loss (tanδ ∼ 0.011) were obtained in ceramics, which demonstrated the superior potential of current studies. The effects of multivalent Mn-ion doping on the phase transition, dielectric characteristics, and defect polarization were systematically investigated based on the experimental results and first-principle calculations. The change of dielectric properties was related to the formation of new defect dipoles ([ M n T i ′ − Y B a • ] and [ M n T i ″ − 2 Y B a • ]). According to the first-principle calculations, the deformation of ceramic structures and the nonuniform distribution of electron density lead to the weakening of chemical bonds and the enhancement of carrier transitions. The interfacial polarization associated with the long-range hopping of oxygen vacancies is the main source of high dielectric constant for Mn15 ceramic samples. Furthermore, all ceramics showed excellent temperature stability and satisfied the EIA X8R standard (−55 °C–150 °C, ΔC/C 25°C ≤ ±15%), which can be explained by the "core-shell" structure. The effect of internal defect structure on polarization mode presented in this work can be applied to the study of BaTiO 3 -based dielectric ceramics. The results have excellent application potential in the BME-MLCC industry. [ABSTRACT FROM AUTHOR]

Polysilsesquioxanes (PSQs) have generated great interest as solution‐processable inorganic polymers for obtaining high‐dielectric‐constant (k) dielectrics. Engineering the side chains in PSQs can enhance the polarization characteristics and provide different functionalities, such as photopatternability and ferroelectric performance. In this study, two types of UV curable high‐k PSQs are prepared by introducing epoxy‐containing side chains to the PSQs: 1) glycidyl epoxy‐containing linear groups and 2) bulky cycloaliphatic epoxy‐containing groups. The physical, chemical, and electrical properties of these two materials after UV curing are investigated. Both PSQ films show high dielectric strength and are successfully patterned after exposure to UV light. The structure of the side chains influences the UV curing behavior and capacitance characteristics of the PSQ dielectrics. These differences determine the driving behavior of the fabricated organic thin‐film transistors, which exhibits either stable or ferroelectric operation. Finally, logic gates and memory cells exhibiting low‐voltage and non‐destructive operations are successfully integrated using UV cured PSQs. This approach for engineering PSQs with the purpose of achieving desirable photopatternability and high dielectric or ferroelectric performance can be used to realize simple and inexpensive solution‐processing techniques for next generation integrated electronics. [ABSTRACT FROM AUTHOR]

Wearable electronics represented by flexible displays and flexible sensors have been attracting enormous attention due to portability, miniaturization and low power consumption. Due to the dramatic increase in the number of display and sensing units, the power consumption and accuracy of the devices are facing great challenges. Active‐matrix thin‐film transistor (TFT) backplanes can effectively reduce signal crosstalk and power consumption of wearable electronics. For TFT devices, the gate insulation layer is one of key factors affecting the device performance such as device mobility, operating voltage, and bias stability, etc. High quality of solution‐processed oxide dielectric films usually are obtained at a high temperature (>400 °C), being a challenge for compatibility with flexible plastic substrates. In this work, low‐temperature annealing processes (the electric oven (EO) and deep ultraviolet (DUV) processing) of high‐k zirconia dielectric films was investigated. Compared to the thermal annealing process, the EO or DUV processing‐annealing process could obtain an approximate dielectric properties with that of thermal annealing process. The EO and DUV processing could effectively promoted the MO framework and the elimination of oxygen defects in the spin‐coating films. DUV processing ZrO2 film annealed at 150 °C exhibited an excellent properties including a large capacitance of 220 nF/cm2 and low leakage current of ~10‐7 A/cm2. These data suggest that combining low‐temperature annealing with EO and DUV irradiation holds great promise for the rapid, low‐temperature production of high‐quality and flexible oxide electronic devices. [ABSTRACT FROM AUTHOR]

To improve the output power of the polydimethylsiloxane (PDMS)-based triboelectric nanogenerators (TENGs), we fabricated an asymmetric TiO2/PDMS composite film in which a pure PDMS thin film was deposited as a capping layer on a TiO2 nanoparticles (NPs)-embedded PDMS composite film. Although in the absence of the capping layer, the output power decreased when the content of TiO2 NPs exceeded a certain value, the asymmetric TiO2/PDMS composite films showed that the output power increased with increasing content. The maximum output power density was approximately 0.28 W/m2 at a TiO2 content of 20 vol.%. The capping layer could be responsible not only for maintaining the high dielectric constant of the composite film but also for suppressing interfacial recombination. To further improve the output power, we applied a corona discharge treatment to the asymmetric film and measured the output power at a measurement frequency of 5 Hz. The maximum output power density was approximately 78 W/m2. The idea of the asymmetric geometry of the composite film should be applicable to various combinations of materials for TENGs. [ABSTRACT FROM AUTHOR]

In this review, an introduction to nanostructured films focusing on cerium oxide (CeO _2 ) as high dielectric constant ( k ) material for silicon-based metal-oxide-semiconductor devices, and subsequently background of using low k silicon dioxide as well as the transition to high k materials was presented. Moreover, the properties of CeO _2 in general and the applications of CeO _2 and doped CeO _2 films as high k passivation layers were reviewed. The beneficial effect of using CeO _2 seed layers on the characteristics of CeO _2 nanostructures was discussed. Moreover, challenges faced by CeO _2 and the potential of doping trivalent cations into the CeO _2 lattice for enhancement of passivation properties were thoroughly discussed.

Polyvinyl alcohol (PVA), polystyrene sulfonic acid (PSSA), and cobalt oxide (Co3O4) nanoparticles are used in the ease and low-cost solution casting method to prepare flexible nanocomposite films. Structural and morphological studies were carried out for the nanocomposites. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies revealed an excellent interaction between the host polymer and Co3O4 nanoparticles. Scanning electron microscopy (SEM) was employed to study the surface morphology of the PVA/PSSA/Co3O4 nanocomposite films, which exhibited homogeneous dispersion of nanoparticles within the host matrix. Stress–strain curves were obtained to evaluate the mechanical properties of PVA/PSSA/Co3O4 nanocomposite films. The dielectric behavior of PVA/PSSA/Co3O4 nanocomposite films was examined by varying the content of Co3O4 nanoparticles in the frequency and temperature range of 100 Hz–1 MHz and 30–150°C, respectively. The 15 wt% of Co3O4 nanoparticles in the PVA/PSSA/Co3O4 nanocomposite films have a high dielectric constant (ɛ) of 511.66 and a relatively high dielectric loss (tan δ) of 1440.25 at low frequency and at 60°C, respectively. In addition, the high AC conductivity (σac) obtained for the 15 wt% of Co3O4 nanoparticles was found to be 1.66 × 10−5 Scm−1. The improvement in the dielectric performance of PVA/PSSA/Co3O4 nanocomposite films evidenced that they could be promising materials for microwave absorption applications. [ABSTRACT FROM AUTHOR]

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO2-(20-x) ZnO-xV2O5. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO4 and VO5 units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V2O5. The AC conductivity was investigated in the frequency range of 40 Hz to 107 Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V2O5. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries. [ABSTRACT FROM AUTHOR]

High dielectric constant carbon nanotubes (CNTs) based polymer composites with enhanced thermal stability are promising materials for energy storage devices because of high breakdown voltage, ease in processing, enhanced flexibility and low cost. In the present work, 3-aminopropyltriethoxysilane (APTES) as additive was used along CNTs as filler and polymethylmethacrylate (PMMA) as matrix to enhance the dispersion of filler in matrix by increasing interfacial interaction between these two. These composites were synthesized by using solution casting method and monitored by FTIR spectroscopy whereas XRD and SEM analyses have been performed to explore the role of APTES in dispersion of CNTs. Significant improvement in the dielectric constant (Dielectric Constant: 40 at 1.6 wt% of CNTs) has been observed on adding small fraction of APTES-CNTs. An impressive increase in thermal stability of the composite was achieved because of APTES. It is noted that weight loss in APTES-CNTs/PMMA composite at 460 °C is less than that of CNTs/PMMA composite at 400 °C. Use of APTES-CNTs appears to be quite encouraging when the obtained values of dielectric constant and results of thermal stability of APTES-CNTs/PMMA are compared with those of pristine CNTs based PMMA (CNTs/PMMA) composites. Mechanism of APTES to control the agglomeration of CNTs in the composite is distinctive and effective in improving the features of composite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The (C 6 H 9 N 2) 2 CoCl 4 compound was successfully synthesized via slow evaporation at room temperature. • The electrical and dielectric properties were studied using the impedance measurements. • The ac conductivity of this compound follows the Jonscher's law. • (C 6 H 9 N 2) 2 CoCl 4 shows a negative temperature coefficient of resistance and charge polarization discharge, suggesting its potential use as a thermistor. • Giant dielectric constant (∼103) is observed close to room temperature. Organic-inorganic hybrid materials have garnered considerable interest due to their unique physical and chemical properties, enabling their use in diverse applications. This study explores the synthesis and characterization of the organic–inorganic hybrid compound (C 6 H 9 N 2) 2 CoCl 4. The compound was successfully synthesized via the slow evaporation method at room temperature. The X-ray diffraction on a single crystal indicated a monoclinic structure in the P 21/c space group. Various analytical techniques were employed to ensure the material's high purity and to investigate its properties. Powder X-ray diffraction and SEM/EDX analysis confirmed the compound's crystalline structure and elemental composition. Raman spectroscopy provided insights into the vibrational characteristics. In contrast, UV–visible absorption and luminescence spectroscopy were used to explore its optical properties, indicating its potential as a semiconductor. The electrical and dielectric properties were studied using complex impedance spectroscopy (CIS), revealing significant frequency and temperature dependence. Additionally, Kohlrausch-Williams-Watts analysis was employed to examine the electric modulus, further elucidating the compound's non-Debye behavior. These methods collectively demonstrate the compound's potential applications in electronic and optical devices. [ABSTRACT FROM AUTHOR]

Electromagnetic interference (EMI) shielding materials play a vital role in human society, especially in light of the rapid development of electronic communication equipment. Therefore, it is urgent to develop green, high-efficiency EMI shielding materials. Wood, as a renewable raw material, possesses significant structural advantages in studying EMI materials due to its unique 3D pore structure. Herein, we report magnetoelectric lignocellulosic matrix composites derived from the delignified wood for efficient EMI shielding. The composite was fabricated by in-situ polymerization of PEDOT conductive coating and magnetic Fe 3 O 4 in delignified wood. The conductive 3D pore structure of Fe 3 O 4 /PEDOT@wood could effectively cause dielectric loss and multiple internal reflections. Combined with the magnetic loss of Fe 3 O 4 , the material exhibited excellent EMI shielding effectiveness (SE), which could be attributed to the synergistic effect of dielectric and magnetic losses. The Fe 3 O 4 /PEDOT@wood showed excellent conductivity (103 S/m), good magnetism (26.7 emu/g), the EMI SE up to 59.8 dB, and high SE A /SE T ratios of∼84.2 % to 95.7 % at 2 mm in X -band. Moreover, the material exhibited a high compressive strength and tensile strength of 100.8 MPa and 18.1 MPa, respectively. Therefore, this work provided a reference for the preparation of high-efficiency EMI shielding materials. [ABSTRACT FROM AUTHOR]

High dielectric constant polymers have been widely studied and concerned in modern industry, and the induction of polar groups has been confirmed to be effective for high permittivity. However, the way of connection of polar groups with the polymer backbone and the mechanism of their effect on the dielectric properties are unclear and rarely reported. In this study, three polyimides (C0-SPI, C1-SPI, and C2-SPI) with the same rigid backbone and different linking groups to the dipoles were designed and synthesized. With their rigid structure, all of the polyimides show excellent thermal stability. With the increase in the flexibility of linking groups, the dielectric constant of C0-SPI, C1-SPI, and C2-SPI enhanced in turn, showing values of 5.6, 6.0, and 6.5 at 100 Hz, respectively. Further studies have shown that the flexibility of polar groups affected the dipole polarization, which was positively related to the dielectric constant. Based on their high permittivity and high temperature resistance, the polyimides exhibited outstanding energy storage capacity even at 200 °C. This discovery reveals the behavior of the dipoles in polymers, providing an effective strategy for the design of high dielectric constant materials. [ABSTRACT FROM AUTHOR]

Flexible polymer composites with high dielectric constants and low dielectric losses at high frequencies are highly desired in microwave and RF applications. However, a high dielectric constant is often obtained at the expense of flexibility because a high loading of filler is needed. In this work, we synthesize a core-shell structured 1D filler by coating high-dielectric-constant PbTiO 3 onto the surface of low-thermal-expansion-coefficient SiC nanofibers, which are then incorporated into the epoxy matrix together with BaTiO 3 nanoparticles to form the multi-phase BaTiO 3 /SiC@PbTiO 3 /epoxy composite film. A high dielectric constant (35 at 100 Hz and 20 at 5 GHz) and a low dielectric loss (0.023 at 100 Hz and 0.13 at 5 GHz) are achieved as the filling content of SiC@PbTiO 3 and BaTiO 3 is 5.24 wt% and 80 wt%, respectively. Prediction models of the effective dielectric constant of polymer-based composites reveal that a continuous polarization network is constructed in the composites owing to the physical contact between BaTiO 3 and PbTiO 3. The construction of the multi-phase filler provides a feasible way to effectively adjust and improve the dielectric properties of polymer-based composite films. [ABSTRACT FROM AUTHOR]

La2/3Cu3Ti4O12 ceramics were prepared by the same method of solid-state reaction as CaCu3Ti4O12 ceramics. The structure and dielectric responses for La2/3Cu3Ti4O12 and CaCu3Ti4O12 ceramics were systematically investigated by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, and impedance analyzer. Compared with CaCu3Ti4O12 ceramics, La2/3Cu3Ti4O12 ceramics with higher density and refined grain exhibit a high dielectric constant (ε′ ~ 104) and two dielectric relaxations in a wide temperature range. The dielectric relaxation below 200 K with an activation energy of 0.087 eV in La2/3Cu3Ti4O12 ceramics is due to the polyvalent state of Ti3+/Ti4+ and Cu+/Cu2+, while the dielectric relaxation above 450 K with higher activation energy (0.596 eV) is due to grain boundary effects. These thermal activated dielectric relaxations with lower activation energy in La2/3Cu3Ti4O12 ceramics both move to lower temperatures, which can be associated with the enhanced polyvalent structure in La2/3Cu3Ti4O12 ceramics. Such high dielectric constant ceramics are also expected to be applied in capacitors and memory devices. [ABSTRACT FROM AUTHOR]

Recent advances in novel electroactive devices have placed new requirements on material development. High-performance dielectric elastomers with good mechanical stretchability and high dielectric constant are under high demand. However, the current strategy for fabricating these materials suffers from high cost or low thermal stability, which greatly hinders large-scale industrial production. Herein, we have successfully developed a novel strategy for improving the dielectric constant of polymeric elastomers via deep eutectic solvent inclusion by taking advantage of the low cost, convenient and environmentally benign synthesis process and high ionic conductivity from deep eutectic solvents. The as-prepared composite elastomers showed good stretchability and a greatly enhanced dielectric constant with a negligible increase in dielectric dissipation. Moreover, we have proven the universality of our strategy by using different types of deep eutectic solvents. It is believed that low-cost, easy-synthesis and environmentally friendly deep eutectic solvents including composite elastomers are highly suitable for large-scale industrial production and can greatly broaden the application fields of dielectric elastomers. [ABSTRACT FROM AUTHOR]

To improve the output power of the polydimethylsiloxane (PDMS)-based triboelectric nanogenerators (TENGs), we fabricated an asymmetric TiO2/PDMS composite film in which a pure PDMS thin film was deposited as a capping layer on a TiO2 nanoparticles (NPs)-embedded PDMS composite film. Although in the absence of the capping layer, the output power decreased when the content of TiO2 NPs exceeded a certain value, the asymmetric TiO2/PDMS composite films showed that the output power increased with increasing content. The maximum output power density was approximately 0.28 W/m2 at a TiO2 content of 20 vol.%. The capping layer could be responsible not only for maintaining the high dielectric constant of the composite film but also for suppressing interfacial recombination. To further improve the output power, we applied a corona discharge treatment to the asymmetric film and measured the output power at a measurement frequency of 5 Hz. The maximum output power density was approximately 78 W/m2. The idea of the asymmetric geometry of the composite film should be applicable to various combinations of materials for TENGs.

Ba(Ti, Sn)TiO3 and (Ba, Nd)TiO3-based solid solutions were synthesized using the solid-state reaction technique. The sequence of phase transformations during synthesis was established. Crystallographic parameters and microscopy were studied. Changes in crystallographic parameters and average grain size with substitution degree were determined. It was found that the introduction of 0.5 wt% manganese oxide (IV) and 2 wt% of low-melting glass AST (Al2O3–SiO2–TiO2) reduces the sintering temperature and improves the dielectric parameters (ε and tan(δ)). It has been shown that the obtained materials are promising for the development of ceramic capacitors. [ABSTRACT FROM AUTHOR]

Modern electrical applications urgently need flexible polymer films with a high dielectric constant (ε r ) and low loss. Recently, the MXene-filled percolative composite has emerged as a potential material choice because of the promised high ε r . Nevertheless, the typically accompanied high dielectric loss hinders its applications. Herein, a facile and effective surface modification strategy of cladding Ti 3 C 2 T x MXene (T = F or O; FMX) with fluorographene (FG) via self-assembly is proposed. The obtained FMX@FG hybrid yields high ε r (up to 108 @1 kHz) and low loss (loss tangent tan δ = 1.16 @ 1 kHz) in a ferroelectric polymer composite at a low loading level (the equivalent of 1.5 wt % FMX), which is superior to its counterparts in our work (e.g., FMX: ε r = 104, tan δ = 10.71) and other studies. It is found that the FG layer outside FMX plays a critical role in both the high dielectric constant and low loss from experimental characterizations and finite element simulations. For one thing, FG with a high F/C ratio would induce a favorable structure of high β-phase crystallinity, extensive microcapacitor networks, and abundant interfacial dipoles in polymer composites that account for the high ε r . For another, FG, as a highly insulating layer, can inhibit the formation of conductive networks and inter-FMX electron tunneling, which is responsible for conduction loss. The results demonstrate the potential of a self-assembled FMX@FG hybrid for high ε r and low loss polymer composite films and offer a new strategy for designing advanced polymer composite dielectrics.

The dielectric performances as well as the effects of Dy3+ ions content at A sites of YMn 2 O 5 (YMO) [ x ​= ​0 (YDM 0) and x ​= ​0.4 (YDM 0.4)] polycrystalline samples were explored. These compounds were synthesized via sol–gel method. X-Ray diffraction and Raman measurements proved the high quality of the compounds that crystallized in an orthorhombic structure with the Pbam space group. Besides, impedance spectroscopy and electrical modulus studies revealed that both samples exhibited a non-Debye's type of relaxation. The decrease of impedance for YDM 0.4 compared to the pure YDM 0 , may be attributed to the decrease in charge transfer resistance. Concerning the fit of impedance spectra, they confirmed that both compounds were simultaneously capacitive and resistive. Furthermore, the activation energies obtained from Modulus and complex impedance were proven to be neighboring, suggesting that the relaxation process refers to electron hopping. For each compound, the evolution of ε ' and tan ​δ with temperature indicated a clearer relaxor behavior, namely the existence of two relaxations. The first one detected at low temperature is related to the charge carriers hopping between Mn3+ and Mn4+ and the second at high temperature is associated with oxygen vacancies. The reduced hopping rate with Dy3+ substitution for Y3+ ions at A sites is responsible for the decrease in dielectric constant and dielectric loss. These significant findings demonstrate that these materials can be invested in a fruitful use in UV photo-detector and power applications in high frequency as microwave, millimeter wave signal processing, for civilian, military and space applications. [Display omitted] • Impedance spectroscopy and electrical modulus study confirms the presence of the non-Debye type of dielectric relaxation. • The reduced hopping rate with Dy3+ substitution for Y3+ ions at A sites for YMn 2 O 5 is in charge of the decrease in dielectric constant and dielectric loss. • Activation energies calculated from the impedance and Modulus proves to be close, which suggests that the relaxation process refers to electron hopping. • For each compound, we observe two relaxations one at low temperature related to the charge carriers hopping between Mn3+ and Mn4+ and the other at high temperature is associated with oxygen vacancies. [ABSTRACT FROM AUTHOR]

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO2-(20-x) ZnO-xV2O5. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO4 and VO5 units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V2O5. The AC conductivity was investigated in the frequency range of 40 Hz to 107 Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V2O5. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries.

High dielectric constant polymers have been widely studied and concerned in modern industry, and the induction of polar groups has been confirmed to be effective for high permittivity. However, the way of connection of polar groups with the polymer backbone and the mechanism of their effect on the dielectric properties are unclear and rarely reported. In this study, three polyimides (C0-SPI, C1-SPI, and C2-SPI) with the same rigid backbone and different linking groups to the dipoles were designed and synthesized. With their rigid structure, all of the polyimides show excellent thermal stability. With the increase in the flexibility of linking groups, the dielectric constant of C0-SPI, C1-SPI, and C2-SPI enhanced in turn, showing values of 5.6, 6.0, and 6.5 at 100 Hz, respectively. Further studies have shown that the flexibility of polar groups affected the dipole polarization, which was positively related to the dielectric constant. Based on their high permittivity and high temperature resistance, the polyimides exhibited outstanding energy storage capacity even at 200 °C. This discovery reveals the behavior of the dipoles in polymers, providing an effective strategy for the design of high dielectric constant materials.

The arrangement of anisotropic dielectric fillers in polymer matrix can lead to a significant enhancement of dielectric properties along a specific direction, enabling the rapid development of integrated circuits and high-performance microelectronic devices. In this work, magnetic barium titanate nanofibers/polyimide composite films (mBT NFs/PI) with vertically oriented structures were constructed with the assistant of magnetic field. The dielectric constant was significantly increased from 20.8 to 39.1 at a filler content of 30 wt%, as compared to the randomly aligned films. However, the breakdown strength was affected. Addressing this issue, an optimized core-shell structure was fabricated by introducing insulated and thermo-conductive boron nitride (BN) "shell" on the surface of mBT NFs by coaxial electrospinning. The obtained mBT@BN/PI nanocomposite exhibits improved thermal conductivity and breakdown strength, while maintaining a high dielectric constant. This work highlights an effective strategy to achieve excellent dielectric properties and thermal conductivity for high-temperature dielectric capacitor materials. [Display omitted] • A flexible dielectric film was fabricated by constructing vertically aligned mBT NFs via magnetic field-induced strategy. • The oriented nanocomposite films showed superior dielectric properties along the direction of the electric field. • High through-plane thermal conductivity is achieved via constructing a vertical and continuous heat transport path of BN. [ABSTRACT FROM AUTHOR]

Preparation of Na and Ni co-substituted CaCu 3 Ti 4 O 12 (CCTO) ceramics through sol-gel method is carried out to enhance the dielectric properties. On the morphology and dielectric properties of CCTO ceramic, the effects of Na and Ni co-substitution are investigated. The results demonstrate that at room temperature, Na and Ni co-substituted Ca 0.993 Na 0.007 Cu 2.95 Ni 0.05 Ti 4 O 12 exhibits significantly increased grain size and consequently a high dielectric constant exceeding 12000 across a broad frequency range (1–105 Hz). Meanwhile, its dielectric loss is reduced to 0.016 at 1 kHz, a phenomenon that can be ascribed to the raised resistance and activation of grain boundary. Furthermore, Ca 0.993 Na 0.007 Cu 2.95 Ni 0.05 Ti 4 O 12 also yields a breakdown field strength of 2.3 kV/cm. The giant dielectric response can be explained by the internal barrier layer capacitor model. These excellent comprehensive performances not only contribute to obtain simultaneously low dielectric loss and high breakdown strength for CCTO ceramics with high dielectric constant, but also can facilitate the practical application of CCTO ceramics in advanced capacitors. • Na or/and Ni substituted CCTO ceramics were synthesized by sol-gel method. • Ca 0.993 Na 0.007 Cu 2.95 Ni 0.05 Ti 4 O 12 possesses low tanδ (0.016) and high ε ′ (13230). • SEM observed a uniform grain size distribution. • The activation energy was calculated by ε′′ temperature spectrum. [ABSTRACT FROM AUTHOR]

La2/3Cu3Ti4O12 ceramics were prepared by the same method of solid-state reaction as CaCu3Ti4O12 ceramics. The structure and dielectric responses for La2/3Cu3Ti4O12 and CaCu3Ti4O12 ceramics were systematically investigated by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, and impedance analyzer. Compared with CaCu3Ti4O12 ceramics, La2/3Cu3Ti4O12 ceramics with higher density and refined grain exhibit a high dielectric constant (ε′ ~ 104) and two dielectric relaxations in a wide temperature range. The dielectric relaxation below 200 K with an activation energy of 0.087 eV in La2/3Cu3Ti4O12 ceramics is due to the polyvalent state of Ti3+/Ti4+ and Cu+/Cu2+, while the dielectric relaxation above 450 K with higher activation energy (0.596 eV) is due to grain boundary effects. These thermal activated dielectric relaxations with lower activation energy in La2/3Cu3Ti4O12 ceramics both move to lower temperatures, which can be associated with the enhanced polyvalent structure in La2/3Cu3Ti4O12 ceramics. Such high dielectric constant ceramics are also expected to be applied in capacitors and memory devices.

Different from the traditional ways for enhancing the dielectric properties of polymers by compositing with rigid electronic conductors, here an alternative strategy is reported via introducing ionically conductive liquid electrolytes as functional fillers. Dielectric constant has significantly improved (up to 600%) by liquid electrolyte inclusions in an elastomer matrix. Moreover, by taking advantage of the inherent transparency of liquid electrolyte fillers, high transparency, good stretchability, and high dielectric constant are achieved simultaneously. Using the composite elastomer, the fabrication of highly sensitive strain sensor is demonstrated with 5–6 times higher sensitivity than the pristine elastomer, and flexible electroluminescent device with greatly lowed driving voltage. The strategy provides new opportunities for novel electroactive polymers, including flexible touchscreen panels and displays, biomimetic soft machines, and smart optics. [ABSTRACT FROM AUTHOR]

The dielectric properties of TiNb 2 O 7 (TNO) thin films are studied in Metal-Insulator-Metal configuration (Au/TiNb 2 O 7 /Pt) devices. The temperature dependence of the dielectric dispersion and the AC conductivity behavior is strongly dependent on TNO thin film thickness. Low thickness (∼236 nm) films shows considerably less variation with temperatures than their thicker counterparts (∼480 nm). These behaviors are explained on physical basis – nearly constant loss (NCL) and Jonscher's Universal Dielectric Response (UDR). The TNO thin films show large dielectric constant (∼ 59–73) and moderate dielectric loss (∼0.07–0.11). The AC conductivity values of the thin films lie in the range of about (10 − 8 to 10 − 9) at 10 kHz. The thicker films show DC conductivity values which are thermally activated with an activation energy of about 0.44 eV. This is slightly higher (about 0.1 eV) than ω p in Jonscher's UDR response and this discrepancy is explained on the basis of mixed ionic electronic conduction in TNO thin films. The possible role of growth morphology in the dielectric response is also briefly mentioned. [ABSTRACT FROM AUTHOR]

Purpose: To present a 3T brain imaging study using a conformal prototype helmet constructed with an ultra‐high dielectric constant (uHDC; εr ~ 1000) materials that can be inserted into standard receive head‐coils. Methods: A helmet conformal to a standard human head constructed with uHDC materials was characterized through electromagnetic simulations and experimental work. The signal‐to‐noise ratio (SNR), transmit efficiency, and power deposition with the uHDC helmet inserted within a 20‐channel head coil were measured in vivo and compared with a 64‐channel head coil and the 20‐channel coil without the helmet. Seven healthy volunteers were analyzed. Results: Simulation and in vivo experimental results showed that transmit efficiency was improved by nearly 3 times within localized regions for a quadrature excitation, with a measured global increase of 58.21 ± 6.54% over 7 volunteers. The use of a parallel transmit spokes pulse compensated for severe degradation of B1+ homogeneity, at the expense of higher global and local specific absorption rate levels. A SNR histogram analysis with statistical testing demonstrated that the uHDC helmet enhanced a 20‐channel head coil to the level of the 64‐channel head coil, with the improvements mainly within the cortical brain regions. Conclusion: A prototype uHDC helmet enhanced the SNR of a standard head coil to the level of a high density 64‐channel coil, although transmit homogeneity was compromised. Further improvements in SNR may be achievable with optimization of this technology, and could be a low‐cost approach for future radiofrequency engineering work in the brain at 3T. [ABSTRACT FROM AUTHOR]

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The discontinuous Galerkin (DG) method for homogeneous bodies has been studied and shown to be an efficient tool for multiscale homogeneous bodies. However, the slow convergence of DG with the block diagonal preconditioner (BDP) is still observed in solving high contrast homogeneous bodies. An efficient preconditioning approach is designed for the DG method in this communication by using the sparsing approach on the near-field matrix of the whole region. The iteration convergence speed of the DG method is improved while the computing resources for constructing the preconditioner are effectively reduced. Numerical experiments demonstrate the capability of the presented DG method for multiscale homogeneous bodies, especially for those with a high dielectric constant. [ABSTRACT FROM AUTHOR]

Polythiophene (PTH) with high electrical conductivity was prepared by oxidative polymerization using FeCl3 and characterized by FTIR, XRD, thermal analysis and conductivity measurement. The synthesized PTH was used to prepare conducting composites based on polypropylene (PP). Electrical, thermal, mechanical and dynamic mechanical properties were studied. An exponential increase of conductivity with respect to PTH content was observed in the composites, indicating the formation of a continuous conducting network. PTH improved the modulus of the composites while decreasing the tensile strength. The composite containing PTH showed higher thermal stability and exceptional dielectric constant. The study was successful in converting a commercial general purpose thermoplastic polymer into a composite suitable for capacitor applications. [ABSTRACT FROM AUTHOR]

The commercialization of the Zn-metal battery is hindered by dendrites and side reactions on the Zn anode. Here, the BaSO 4 coating is designed to address the problem of the Zn anode. The porous structure of the BaSO 4 coating improves the wettability to induce relatively uniform electrolyte flux and inhibits the two-dimensional diffusion of Zn2+, suppressing the growth of dendrites on the Zn anode. The BaSO 4 leads to a "space charge polarization" to promote the separation of positive and negative charge centers, the electrostatic effect promotes the transportation of Zn2+ and reduces the occurrence of side reactions. Consequently, the BaSO 4 @Zn||BaSO 4 @Zn battery displays a longer lifespan (122 h–1200 h) and a lower polarization (74.0 mV–47.2 mV) at 2 mA cm−2. The full battery exhibits an extended lifespan (3000 cycles) and a stable coulombic efficiency at 5 A g−1 when coupled with the K 2 V 6 O 16 ·1.5H 2 O (KVO) cathode. This work serves as a reference for solving problems and promoting the application of the Zn-metal battery. • Discovery a simple coating for highly reversible Zn anode. • BaSO 4 coating inhibits the growth Zn dendrites and suppresses side reactions. • BaSO 4 @Zn has a long lifespan of 1200 h at 2 mA cm−2. • BaSO 4 @Zn||KVO battery display an extended lifespan of 3000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

This work focused on the influence of annealing temperature on CoCr 2 O 4 nanoceramics synthesized through a co-precipitation method without the aid of surfactants or templates. The study for the first time correlated the electrical and optical properties of this nanomaterial and investigated the underlying physical concepts through probable theoretical demonstrations. Structural analysis using X-Ray diffractometry, Rietveld Refinement, and FTIR spectroscopy revealed a cubic crystal structure (space group Fd-3m) and the evolution of spinel-type AB 2 O 4 phase. The crystallite size, determined via the Debye-Scherrer method, exhibited growth from 5.2 nm to 23.7 nm due to an increase in annealing temperature from 400 °C to 600 °C. Moreover, FESEM images exhibited an increase in grain size due to nanoparticle agglomeration at elevated annealing temperatures. The direct bandgap decreased from 2.55 eV to 2.40 eV as the annealing temperature escalated. The semi-conducting nature was also verified from Band structure, DOS, and I–V analysis. Crystallinity-mediated behaviour of various optical properties and emission spectra were carefully scrutinized. Frequency and calcination temperature-dependent dielectric properties and Nyquist plot revealed MWS-type polarization and semiconducting arc-like behaviour. The Coats and Redfern model computed activation energy of the system was 24.69 kJ/mol. These findings supported the suitability of this nanomaterial in optoelectronic applications. To study the effect of post-calcination temperature on all the pertinent properties of CoCr 2 O 4 nanoceramics and synchronization of theoretical and experimental demonstrations were the prime goal of this communication. [Display omitted] • High temperature sustainable low-cost chemical synthesis of spinel nanoceramics. • Impact of post-annihilation on size, microstructural defects, and optical bandgap. • Scrutiny of optoelectronic properties and correlation with theoretical demonstrations. • Quantum confinement effect leads to high dielectric constant with low tangent loss. • Establishment of a potential optoelectronic as well as novel dielectric material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Morphotropic phase boundary of HZO film with high- κ is achieved by tuning H 2 O dose. • Leakage current is reduced by inserting an Al 2 O 3 interfacial layer. • Good endurance against write/read cycles and high temperatures is realized. For the miniaturization of dynamic random-access memory (DRAM), it is necessary to obtain low equivalent oxide thickness (EOT) and low leakage capacitor materials with complementary metal-oxide semiconductor (CMOS) process compatibility. Herein, we explore the influence of the dose of H 2 O reactants on the phase structure and electrical characteristics of Hf 0.3 Zr 0.7 O 2 (HZO) thin films during the atomic layer deposition (ALD). By controlling the H 2 O dose as well as other conditions including inserting alumina, adjusting annealing temperature and electric field cycling, a high dielectric constant of ∼45 (EOT ∼ 0.54 nm) and low leakage current density (<7.7 × 10−8 A/cm2 at ±0.5 V) are achieved in the TiN/Al 2 O 3 (∼0.3 nm)/Hf 0.3 Zr 0.7 O 2 (∼6 nm)/TiN capacitor near the morphotropic phase boundary (MPB). Furthermore, the dielectric constant remains above 40 with endurance >1012 cycles (even extrapolated to 1015 cycles under voltage pulse of 0.5 V @10 MHz) at both room temperature and 85 °C. These results are helpful for achieving a high dielectric constant and low leakage for future generation DRAM capacitor materials. [ABSTRACT FROM AUTHOR]