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Excellent spinel microwave dielectric ceramics (1- x)Zn 2 TiO 4 - x Li 2 MgTi 3 O 8 (ZTLMT x , x = 1/3 and 2/3) were prepared at relatively low densification temperatures of 1100 °C and 1080 °C, respectively. A disordered cubic phase with space group Fd -3 m was formed at x = 1/3, whereas an ordered cubic phase with space group P 4 3 32 was formed at x = 2/3. The ceramics at x = 1/3 and 2/3 exhibited promising microwave dielectric properties of ɛ r = 18.27 and 22.96, Q × f = 91,877 GHz and 75,186 GHz, and τ f = −42.3 ppm/°C and −21.05 ppm/°C, respectively. The large deviation between the experimental ԑ r and theoretical ε th of 1/3 and 2/3 ceramics were 18.3 % and 57 %, respectively, due to the underestimation of the ionic polarizability of Ti4+. The difference in their ɛ r , Q × f , and τ f were discussed by the structure, FWHM of A 1g , lattice energy and bond energy in detail. [ABSTRACT FROM AUTHOR]

Novel ultra-high Q ceramic ZnMgTiO 4 was prepared using solid-state synthesis. For the first time, the crystal structure, sintering behaviour and microwave dielectric properties of ZnMgTiO 4 ceramic were investigated. ZnMgTiO 4 ceramics formed a cubic spinel (space group Fd 3 ‾ m) single-phase for sintering within 1340 °C-1400 °C, with Zn2+ occupying the tetrahedral site, Mg2+ and Ti4+ distributing randomly in the octahedral site, whereas a trace of MgTiO 3 appeared at 1420 °C. At 1400 °C: ϵ r = 16.8, Q × f = 202,021 GHz, and τ f = −38 ppm/°C, excellent microwave dielectric properties were obtained, and CaTiO 3 compensated the negative τ f to near-zero. A substantial 29% deviation between the measured ϵ r and the theoretical ϵ th could be attributed to the potential underestimation of ionic polarizability of Ti4+. Phillips–Van Vechten–Levine theory suggested that dielectric polarization and intrinsic loss were primarily influenced by the Ti–O bonds. As a conclusion, ZnMgTiO 4 ceramic emerges as a promising candidate for 5G/6G wireless communication devices. [ABSTRACT FROM AUTHOR]

To obtain high performance dielectric composites, novel functionalized MoS 2 nanosheet/poly(arylene ether nitrile) (PEN) nanocomposite films were demonstrated. For this purpose, the MoS 2 nanosheets prepared by hydrothermal method were modified via mussel inspired co-modification and crosslinking of polydopamine (PDA) and polyethylenimine (PEI), followed by incorporating into the PEN matrix to form the MoS 2 @(PDA + PEI)/PEN nanocomposite films through a simple solution casting method. The surface modification of MoS 2 nanosheet was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The effect of functionalized MoS 2 mass fraction on the performance of PEN composites was also detailed investigated. Owing to the well interfacial compatibility between MoS 2 nanosheet and PEN matrix, the resulting PEN nanocomposite film with 10 wt% MoS 2 @(PDA + PEI) exhibited excellent comprehensive performance, including high dielectric constant of 8.3, low dielectric loss of 0.02 at 1 kHz and outstanding frequency stable. Moreover, it also showed excellent thermal stability (T 5% > 490 °C) and mechanical properties that the tensile strength and modulus reached 120.3 MPa and 2468.2 MPa, respectively. Such remarkable performance may be suitable for dielectric applications in special demand. Our study provides a new strategy to obtain high-performance dielectric materials. Unlabelled Image • Unique surface functionalization of MoS 2 nanosheets is realized through the mussel inspired co-modification of PDA and PEI. • The functionalized MoS 2 shows good dispersion and interfacial adhesion with PEN. • The nanocomposites show excellent thermal, mechanical properties and enhanced dielectric properties. [ABSTRACT FROM AUTHOR]

Poly(arylene ether nitrile) (PEN) copolymers (HQ/RS-PEN) containing different proportions of hydroquinone (HQ-PEN) block and resorcinol (RS-PEN) block were synthesized, and their crystalline, mechanical, and dielectric properties were investigated. Three HQ/RS-PEN copolymers with 10%, 20%, and 30% of RS-PEN blocks were prepared via condensation polymerization of HQ and RS with 2,6-dichlorobenzonitrile. The PEN copolymers were characterized and confirmed by Fourier transform infrared spectroscopy, intrinsic viscosity, and thermal analyses. With the addition of RS-PEN block, the flexibility of PEN copolymers was increased. In addition, even though the high loading content of RS-PEN block was incorporated, the PEN copolymers still exhibited relatively high dielectric constant, whereas the dielectric loss decreased. Furthermore, to investigate the effect of treatment time and temperature on the physical properties of crystalline PEN copolymers, HQ/RS-PEN20 was isothermally treated at different temperatures (280°C, 300°C, 310°C, 320°C, and 330°C) for a constant time and at a constant time for different hours (1, 2, 3, 4, and 5 h). After the optimization of the crystallization of HQ/RS-PEN polymer, excellent mechanical and dielectric properties of copolymers were obtained. The results showed that when isothermally treated at 320°C for 2 h, the HQ/RS-PEN20 showed optimal properties of tensile strength of 117.6 MPa and dielectric constant of 4.07 at 1 kHz. [ABSTRACT FROM AUTHOR]

In this paper, barium titanate@zinc phthalocyanine (BT@ZnPc) and graphene oxide (GO) hybrids (BT@ZnPc-GO) connected by calcium ions are prepared by electrostatic adsorption, and then introduced into polyarylene ether nitrile (PEN) to obtain composites with enhanced dielectric and crystallization properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results confirm the successful fabrication of the BT@ZnPc-GO. BT@ZnPc-GO and PEN composites (BT@ZnPc-GO/PENs) are obtained through the solution-casting method. BT@ZnPc-GO demonstrates well compatibility with PEN due to its unique structure and the organic layer of ZnPc at the periphery of BT. On the other hand, BT and GO contribute a high dielectric constant of the composites obtained. In addition, the BT@ZnPc-GO can be used as a nucleating agent to promote the crystallization of the nanocomposites. As a result, The BT@ZnPc-GO/PEN exhibits a dielectric constant of 6.4 at 1 kHz and crystallinity of 21.03% after being isothermally treated at 280 °C for 2 h at the GO content of 0.75 wt %. All these results indicate that the hybrid nanofiller BT@ZnPc-GO can be an effective additive for preparing high-performance PEN-based nanocomposites. [ABSTRACT FROM AUTHOR]

Enhanced dielectric and mechanical properties of polyarylene ether nitrile (PEN) are obtained through secondary dispersion of polyaniline functionalized barium titanate (PANI-f-BT) by hot-stretching. PANI-f-BT nanoparticles with different PANI content are successfully prepared via in-situ aniline polymerization technology. The transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopic instrument (XPS) and Thermogravimetric analysis (TGA) results confirm that the PANI layers uniformly enclose on the surface of BaTiO3 nanoparticles. These nanoparticles are used as functional fillers to compound with PEN (PEN/PANI-f-BT) for studying its effect on the mechanical and dielectric performance of the obtained composites. In addition, the nanocomposites are uniaxial hot-stretched by 50% and 100% at 280 °C to obtain the oriented nanocomposite films. The results exhibit that the PANI-f-BT nanoparticles present good compatibility and dispersion in the PEN matrix, and the hot-stretching endows the second dispersion of PANI-f-BT in PEN resulting in enhanced mechanical properties, crystallinity and permittivity-temperature stability of the nanocomposites. The excellent performances of the nanocomposites indicate that a new approach for preparing high-temperature-resistant dielectric films is provided. [ABSTRACT FROM AUTHOR]

The core-shell structured polyaniline-functionalized-BaTiO3 (BT@PANI) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are completely stabilized on the surface of the BaTiO3 core. In addition, the BT@PANI nanoparticles are regarded as the hybrid nanofillers to prepare PEN/BT@PANI nanocomposite films with a PEN matrix. The research results indicate that the surface functionalized nanoparticles facilitate the compatibility and dispersibility of them in the PEN matrix, which improves the properties of the PEN/BT@PANI nanocomposites. Specifically, the PEN/BT@PANI nanocomposites exhibit thermal stability, excellent permittivity-frequency, and dielectric properties-temperature stability. Most importantly, the energy density of nanocomposites is maintained at over 70% at 180 °C compared with that at 25 °C. All these results reveal that a new way to prepare the high-performance PEN-based nanocomposites is established to fabricate an energy storage component in a high temperature environment. [ABSTRACT FROM AUTHOR]

In recent years, boron nitride and graphene have been widely used in various industries due to their special properties. It is known that the introduction of GO into matrix resin can achieve high dielectric constant and low breakdown strength. In this work, a filler of h-BN-GO was designed through a simple one-step ultrasonic blending method without any surface modification, which is based on the π-π interaction between graphene and boron nitride because of their similar layered structure. Then, a flexible dielectric film with good dielectric breakdown strength and thermal conductivity was obtained through introducing the h-BN-GO fillers into poly(arylene ether nitrile). The various testing results show that the nanocomposites possess high mechanical properties (tensile strength > 99 MPa) and thermal stability (T 5% > 453 °C). Notably, as the h-BN-GO content increases from 0 wt% to 7.5 wt%, the dielectric constant increases from 4.2 to 7.4 at 1 kHz. Most importantly, when the filler content is 7.5 wt%, the breakdown strength of the h-BN-GO/PEN film is 91.6% higher than that of the GO/PEN film with the same load. Therefore, these h-BN-GO/PEN nanocomposite films exhibit potential in applications as flexible dielectric films. Image 1 Without any surface modification, the h-BN-GO mixture was prepared by a simple one-step ultrasonic blending method through π-π interaction. The h-BN-GO/PEN nanocomposite films with high dielectric constant and breakdown strength were prepared via a simple solution-casting method. According to these desirable performances, the h-BN-GO/PEN nanocomposite films exhibit potential applications in flexible dielectric films. • The h-BN-GO was prepared by a simple one-step ultrasonic method. • The combination of h-BN and GO is face-to-face via π-π interactions. • Composite films have good dielectric constant and breakdown strength. [ABSTRACT FROM AUTHOR]

The properties of polymer based composites are seriously affected by the dispersibility of fillers in the polymer matrix. Chemical modification the surface of fillers is generally employed to achieve excellent dispersibility. However, chemical modification of the additives complicates the fabricating process and increases the cost of the prepared composites. Herein, we report enhancing dielectric and energy storage properties of polyarylene ether nitrile (PEN) by incorporating one-dimensional nanostructured barium titanate nanowires (BT-NWs). Four BT-NWs whose mean aspect ratio is 8.6, 11.6, 16.8 and 30.7, respectively, are prepared via a two-step hydrothermal reaction procedure and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Afterwards, BT-NW/PEN nanocomposites are prepared by solution casting method. Results demonstrate that BT-NWs are dispersed in the PEN substrate without aggregation and excellent mechanical properties of the composites are obtained. Due to the nanowire nature of the BT-NWs, the dielectric constant of the BT-NW/PEN composites increases obviously with the increasing content and mean aspect ratio of BT-NW. The prepared BT-NW/PEN composites demonstrate an energy storage density up to 1.55 J/cm3, intensifying competitiveness of BT-NW/PEN composites for applications as film capacitors. [ABSTRACT FROM AUTHOR]