Journal of Advanced Dielectrics
Xi Yao
[in Chinese], and [in Chinese]

Organic molecular ferroelectric diisopropylammonium chloride (dipaCl) was successfully synthesized using diisopropylamine, hydrochloric acid (57%) and methanol solution. Dielectric permittivity, impedance, modulus spectroscopy and conductivity were systematically studied by Capacitance–Conductance (CP – G) measurements in the temperature range of 373–445 K. Dielectric property tests clearly show that the organic molecular ferroelectric dipaCl obeys Curies–Weiss law 1/e = (T–T0)/C. The real (Z′) and imaginary (Z″) parts of the electrical modulus were calculated from the various values of e′ and e″. It is shown that AC conductivity satisfies the relation s(w) ∞ wn, where the power exponent n depends on temperature and frequency. From Arrhenius equation, the activation energies Es and Eh are also calculated which describes the complete conduction mechanism of dipaCl.

Jan. 01, 1900
  • Vol. 11 Issue 4 2150015 (2021)
  • Sherif Haggag, Loai Nasrat, and and Hanafy Ismail

    This paper presents the modification occurred to the dielectric strength feature of low density polyethylene compounded with nano magnesia (LDPE/MgO). MgO nanoparticles were prepared using sol–gel technique, MgO filler surface was functionalized to improve the interfacial bonding. Specimen’s groups of composites with different filler concentrations were fabricated by mix blend method. Samples exposed to various salinity media by immersion, dielectric strength test was applied on each set according .material. Tests results utilized to learn Artificial Neural Network in order to acquire the value of dielectric strength of compounds having similar composition but containing different doping amounts or influenced with various salinity level media. The dielectric strength is enhanced by the addition of MgO nanofiller. From the investigation of the obtained results, it is concluded that additives of 1.4% filler concentration by weight is the optimum MgO content for LDPE/MgO nanofiller material. We think that this paper may promote a good researching methodology that gather both empirical work and numerical tools in this field.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150016 (2021)
  • [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]

    Based on the biological characteristics of tulip, the low driving voltage and fast response of ionic polymer metal composite (IPMC), we analyzed the fabrication, morphology and performance of the platinum IPMC (Pt-IPMC) and selected the right IPMC for driving bionic tulip. The preparation and performance of IPMC was analyzed first in this paper such as blocking force, output displacement and bending angle of IPMC under the different directed current voltage (DC). The optimal IPMC sample size and driving voltage were selected based on tulip blooming angles and the strain energy density of IPMC, which completed the blooming process of bionic tulip. The feasibility of IPMC used in driving bionic field was fully proved in this paper, which laid a foundation for the application of IPMC in driving biomimetic biological robots.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150017 (2021)
  • [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]

    Ceramics-based capacitors with excellent energy storage characteristics, fast charging/discharge rate, and high efficiency have received significant attention. In this work, Na0.73Bi0.09NbO3 (NBN) ceramics were processed through solid-state sintering route. The investigated ceramics were crystallized in a single perovskite phase. Dense microstructure, with small average grain size (~0.92 mm) is obtained for the investigated ceramics. A high dielectric constant >1000 accompanied by a low dielectric loss was achieved for these ceramics at ambient temperature. A recoverable energy density ~0.92 J/cm3 and ultra-high efficiency of 96.33% at 138 kV/cm were obtained at room temperature. Furthermore, a lower discharging time of 0.14 ms was also achieved. This material is a suitable candidate for power pulsed applications.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150018 (2021)
  • [in Chinese], and [in Chinese]

    Compositional-gradient BaTi1.xSnxO3 thin films on Pt(100)/Ti/SiO2/Si substrates are fabricated with sol–gel using spin coating. All of the structures of the prepared thin films are of single-phase crystalline perovskite with a dense and crack-free surface mor-phology. BTS10/15/20 thin film exhibits enhanced temperature stability in its dielectric behavior. The temperature coefficient of capacitance TCC20–150 in the temperature range from 20 °C to 150 °C is .0.9 × 10.4/ °C and that of TCC20–(–95) in the temperature range from 20 °C to .95 °C is .3.8 × 10.4/ °C. Furthermore, the thin films show low leakage current density and dielectric loss. High and stable dielectric tunable performances are found in BTS10/15/20 thin films: the dielectric tunability of the thin films is around 20.1% under a bias voltage of 8 V at 1 MHz and the corresponding dielectric constant is in the range between 89 and 111, which is beneficial for impedance matching in circuits. Dielectric tunability can be obtained under a low tuning voltage, which helps ensure safety. The simulated resonant frequency of the compositional-gradient BTS thin films depends on the bias electric field, showing compositional-gradient BTS thin films could be used in electrically tunable components and devices. These prop-erties make compositional-gradient BTS thin films a promising candidate for dielectric tuning.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150019 (2021)
  • [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]

    Present study is carried out to understand the effect of conducting polymer, polypyrrole (PPy) on structural, morphological, ther-mal and dielectric properties of bio-compatible polymer blend film of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). The growth of PPy in the matrix of PVA–PVP was analyzed using XRD, FT-IR and SEM studies. The shifting in positions and broadening of XRD diffraction peaks of PVA–PVP-PPy from that of PVA–PVP indicates the structural modification and reduction in the crystallinity of the PVA–PVP due to incorporation of PPy. The SEM studies suggest scattered growth of PPy in PVA–PVP matrix at lower concentration of pyrrole monomer. As the monomer concentration is increased, the uniform and interconnected growth of PPy was observed in SEM micrographs. The TGA thermograms show faster thermal degradation of PVA–PVP- PPy films at lower temperature as compared to PVA–PVP films. The blend films of PVA–PVP- PPy exhibited enhanced values of dielectric constant and ac conductivity as compared to the virgin blend film which are observed to increase with increasing con-centration of PPy. The high dielectric constant with high ac conductivity exhibited by PVA–PVP-PPy film suggests its possible application as flexible dielectric material for the development of biosensors, energy storage devices in field of green organic electronics.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150020 (2021)
  • [in Chinese], [in Chinese], and [in Chinese]

    The effects of polymorphic form and particle size of SiO2 fillers on the dielectric, mechanical and thermal properties of SiO2–Poly-etheretherketone (SiO2–PEEK) composites were investigated in this paper. Strong low frequency (<10Hz) Debye-like dielectric dispersions could be observed for all samples. The dielectric permittivity at high frequencies of the composite exhibits little morphology or particle size-sensitive characteristics of the SiO2 fillers. All the composites obtained in this case demonstrate the dielectric permittivities of ~3.5 at high frequencies. The crystalline a-cristobalite filled composite exhibits lower dielectric loss and mechanical strength, but larger thermal expansion coefficient and thermal conductivity, compared with the similar particle sized amorphous SiO2 filled one. The crystalline a-quartz filled composite demonstrates the lowest mechanical strength and high-est dielectric loss. An increase in particle size of the spherical fused silica fillers decreases the dielectric loss, while increases the thermal conductivity of the composite. The flexural strength of the composite reaches the maximum value of 113.MPa when the particle size of spherical SiO2 filler is ~10 μm. Particle packing by combining optimal amounts of differently sized spherical fused silica fillers leads to a substantial improvement of mechanical strength (153MPa) coupled with reasonable dielectric and thermal properties due to the synergic effect (dielectric permittivity (εr) = 3.35, dielectric loss (tanδ) = 1.63 × 10.3 @10 GHz, thermal conductivity (l) = 0.74 W/m*k (90 °C), coefficient of thermal expansion (a) = 23.6ppm/°C and relative density (r) = 99.72%).

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150021 (2021)
  • [in Chinese], and [in Chinese]

    Nanoparticles succeeded to enhance the dielectric properties of industrial insulation but the presence of voids inside the power cable insulation still leads to formation high electrical stress inside power cable insulation material and collapse. In this paper, the dielectric strength of new design nanocomposites has been deduced as experimental work done to clarify the benefit of filling nanoparticles with different patterns inside dielectrics. Also, it has been studied the effect of electrical stress distribution in presence of air, water and copper impurities with different shapes (cylinder, sphere and ellipse) inside insulation of single core. In simulation model, it has been used finite element method (FEM) for estimating the electrostatic field distribution in power cable insulation. It has been applied new strategies of nanotechnology techniques for designing innovative polyvinyl chloride insula-tion materials by using nanocomposites and multi-nanocomposites. Finally, this research succeeded to remedy different partial discharges (PD) patterns according to using certain types and concentrations of nanoparticles.

    Jan. 01, 1900
  • Vol. 11 Issue 4 2150022 (2021)
  • [in Chinese]

    Jan. 01, 1900
  • Vol. 11 Issue 4 1 (2021)
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