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The serious deterioration of the energy density of polymer energy storage dielectrics in high temperature environment is the main reason to curb the in‐depth application of dielectric film capacitors in the field of modern electrical and electronic engineering. Here, aiming at the problem of low dielectric constant of polymer dielectric, a simple, low‐cost method is proposed to grow inorganic polar functional layer on surface of polymer film in situ, which effectively improves the polarization characteristics of polymer dielectric at high temperature. The in situ growth of Ti(OH)4 inorganic polar functional layer on surface of polyetherimide (PEI) film noteworthy to improve the energy storage performance of dielectric film. The energy storage density of 4.59 J/cm2 is obtained at 150°C and 600 MV/m, which is 1.18 times that of PEI film under the same condition. The significant enhancement of high temperature energy storage density can be attributed to introduction of functional layer, which effectively improves the dielectric properties and polarization intensity of dielectric film. Furthermore, the facile preparation method provided in this paper can be applied to various thin films under the premise of controllable cost, which is of great significance to improve the high temperature energy storage characteristics of polymer dielectric. [ABSTRACT FROM AUTHOR]

This paper presents the effect of addition of dielectric barrier discharge (DBD) plasma‐treated nano‐Al2O3 particles on electrical treeing characteristics of epoxy resin (EP) at 30, 60, and 90°C, respectively. The electrical treeing and simultaneous partial discharge measurements, surface potential decay, scanning electron microscope, Fourier transform infrared spectrograms and differential scanning calorimetry are adopted to analyze the influence of plasma‐treated nano‐Al2O3 particles on the different insulation properties of EP and its composites. The results show that the high temperature adversely affects the electrical tree initiation, growth rate, and discharge activities of the EP nanocomposites. The DBD‐treated nano‐Al2O3 particles increase the electrical tree initiation voltage of the EP nanocomposites compared to the nanocomposite with the untreated nano‐Al2O3 particles. In contrast, the electrical tree growth rate decreases in the EP nanocomposite with the DBD treated nano‐Al2O3 particles at high temperatures. It is found that DBD treated nanoparticles affect the trap density and energy level of the composites by generating new chemical bonds, and then change their electrical properties. A charge carrier transport model is proposed to explain the obtained experimental results. [ABSTRACT FROM AUTHOR]

This paper presents the effects of the filler type and testing temperature on the charge dynamics and thermal properties of the epoxy resin. The micro‐nano hybrid composites with different content of the micro and nano aluminum nitride (AlN) fillers are fabricated. The morphology of micro‐nano hybrid composites is characterized. Electrical testing and thermal analysis methods are adopted to analyze its electrical and thermal performance. The results show that the space charge accumulation is suppressed and the charge decay process is facilitated in the hybrid composites. The electrical performances of the hybrid composites are enhanced by the nano‐fillers. The apparent mobility and activation energy are decreased with nano‐AlN fillers in the composites at the high temperature. The glass transition temperature and thermal stability of the materials is improved with the nano‐AlN. A hypothetical mechanism is proposed to explain the charge carrier injection and transport of the composites at different temperatures. [ABSTRACT FROM AUTHOR]

In this paper, the results of dielectric investigations on four different solid solutions of PbMg1/3Nb2/3O3‐PbSc1/2Nb1/2O3‐PbZn1/3Nb2/3O3 (PMN‐PSN‐PZN) are presented in a wide temperature range (from room temperature to 1100 K). At higher temperatures (above 600 K) and low frequencies, the electrical conductivity dominates in properties of these ceramics and the Maxwell–Wagner relaxation appears. The DC conductivity has some change in slope close to the Burns temperature. The value of conductivity activation energy is typical for oxygen vacancies conductivity. Close to the Burns temperature, anomalous behavior of the intrinsic dielectric permittivity is also observed due to the appearance of dielectric relaxation in the terahertz frequency range caused partially by dynamics of polar nanoregions and mainly by overdamped optical soft mode which softens toward T*. [ABSTRACT FROM AUTHOR]

To explore high thermal properties, low dielectric constant and loss for copper clad laminates, poly(phenylene oxide) (PPE) with different end groups (allyl and epoxide groups) were successfully prepared. Firstly, low molecular weight polyphenylene ether was synthesized using the redistribution method. Then the polyphenylene ether thermosetting polymers by modifying their terminal hydroxyl groups were reported and their fundamental materials properties were compared. Through property tests and data analyses, it was found that PPE with vinyl end groups had the best performances, especially high glass transition temperature (about 230°C), the thermal conductivity was 0.32–0.38 Wm−1 K−1, low dielectric constant (about 2.5) and low dielectric loss (about 4.4 × 10−3). The possible reason was that the main chain of polyphenylene ether contains non‐polar crosslinkable group (CC). In a word, through properties comparison of thermosets of PPE, the results demonstrated that the materials of all systems were suitable for using as printed circuit boards. [ABSTRACT FROM AUTHOR]

The dielectric properties of CuCrO2 bulk and thin films are studied by evaluating the complex dielectric function ε. In addition to the small peak near the Néel temperature TN, a secondary broad peak is found at high temperatures around Tm=450 K≫TN. As a feature of relaxor ferroelectrics, the maximum temperature Tm increases with increasing frequency. The real part of ε decreases with increasing magnetic field h and the peak at TN vanishes. The secondary peak becomes smaller and is broadened with increasing magnetic field. ε increases with increasing film thickness. Near Tm, the dielectric function offers a critical behavior expressed by an exponent γ=1.74. Using scaling arguments, critical exponents β=0.13 and δ=13.38 are deduced. The exponents depend on the film thickness. While β increases, the exponent γ is reduced with increasing film thickness. [ABSTRACT FROM AUTHOR]

There is a great demand to develop ferroelectric ceramics with both high piezoelectric coefficient and broad temperature usage range for emerging electromechanical applications. Herein, a series of Sm3+‐doped 0.25Pb(Mg1/3Nb2/3)O3‐(0.75−x)PbZrO3‐xPbTiO3 ceramics were fabricated by solid‐state reaction method. The phase structure, dielectric and piezoelectric properties were investigated, where the optimum piezoelectric coefficient d33 = 745 pC/N and electromechanical coupling factor k33 = 0.79 were obtained at the morphotropic phase boundary composition x = 0.39, with good Curie temperature TC of 242°C. Of particular importance is that high‐temperature stability of the piezoelectric and field‐induced strain was obtained over the temperature range up to 230°C for the tetragonal compositions of x = 0.40. The underlying mechanism responsible for the high piezoelectricity and temperature stability is the synergistic contribution of the MPB and local structural heterogeneity, providing a good paradigm for the design of high‐performance piezoelectric materials to meet the challenge of piezoelectric applications at elevated temperature. [ABSTRACT FROM AUTHOR]

The need for electronics to operate at temperatures of 200°C and above continues to grow. These applications include avionics, aerospace, automotive, downhole drilling, mining, and many others. To satisfy this demand, a significant amount of research and development has been conducted. Despite the efforts, the number of new electronic components designed specifically for high‐temperature operation is still relatively limited. In Low Temperature Co‐fired Ceramic (LTCC) packages, LTCC materials are generally used as the host media for a number of pre‐fabricated semiconductor components. As a result, reliability of the entire LTCC package largely depends on the performance of the least robust component. Ferro A6M‐E and Ferro L8 are the two well‐established and recognized LTCC dielectrics widely used for mid and high frequency LTCC applications, including several high reliability aerospace and defense applications that require demanding Mil‐Spec qualifications. This study is our first attempt to characterize and understand basic high‐temperature dielectric properties of these two commercial LTCC materials. The secondary objective is to initiate a dialogue in attempt to establish reliability requirements for LTCC packages dedicated for high‐temperature operation. [ABSTRACT FROM AUTHOR]