Superhard three-dimensional B<sub>3</sub>N<sub>4</sub> with two-dimensional metallicity

Xie, Chenlong; Ma, Mengdong; Liu, Chao; Pan, Yilong; Xiong, Mei; Gao, Guoying; Xu, Bin; Tian, Yongjun; Zhao, Zhisheng

doi:10.1039/c7tc00429j

Cited by 19 publications

(21 citation statements)

References 25 publications

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“…Because of the low e r 0 of ZnO (e r 0 E 10), 26 both the nanocomposites have relatively low e r 0 s in comparison with PMMA/BaTiO 3 composites. 4,8,9 In addition, PMMA-ZnO has a smaller e r 0 than PMMA/ZnO, resulting from the better dispersivity of the ZnO nanoparticles for PMMA-ZnO. The same phenomenon has already been reported for a PMMA/BaTiO 3 composite system, and a detailed explanation is provided.…”

Section: Optical and Dielectric Properties Of The Molded Samplessupporting

confidence: 73%

“…BaTiO 3 , one of the ferroelectric metal oxides, has been most widely used for enhancement of e r 0 . [2][3][4][5][6][7][8][9][10] On the other hand, for other dielectric applications such as variable capacitors, pressure sensors, and touch sensors, a change of C for these systems is important, and high e r 0 is not always required. [11][12][13][14][15][16][17] The distance between two electrodes d and/or the area of the electrodes S are varied by physical operations, changing the C for the systems: C = e 0 e r 0 S/d, where e 0 is the permittivity of vacuum.…”

Section: Introductionmentioning

confidence: 99%

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Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Hayashida

Takatani

2016

J. Mater. Chem. C

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A series of poly(methyl methacrylate)-grafted ZnO nanoparticles (PMMA-ZnO) were synthesized using a surface-initiated polymerization technique and the optical and dielectric properties of PMMA-ZnO were studied. The dielectric constant e r 0 of PMMA-ZnO thin films was highly increased by irradiation of UV light. It is indicated that electrons in the ZnO nanoparticles are excited from a valence band to a conductive band by absorption of UV light, resulting in a large increase in e r 0 owing to Maxwell-Wagner polarization of the resultant free electrons. On the other hand, the dissipation factor (tan d) of PMMA-ZnO is very low and almost constant during UV irradiation because PMMA-ZnO is electrically insulated by the grafted PMMA chains on the ZnO nanoparticles. Also, it was confirmed that due to the grafted PMMA chains, PMMA-ZnO nanocomposites exhibited low light scattering in addition to strong absorption of UV light. The low light scattering of PMMA-ZnO would enhance the absorption efficiency of UV light and therefore contribute to the large increase in e r 0 for PMMA-ZnO. Thus, PMMA-ZnO is a promising material for high sensitivity and low loss UV light sensors using the change in e r 0 .

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Section: Optical and Dielectric Properties Of The Molded Samplessupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Hayashida

Takatani

2016

J. Mater. Chem. C

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“…1,2 Polymers generally display the characteristics of thermally activated charge transport, leading to sharply increased leakage currents with increasing temperature. [3][4][5] Consequently, while polymer dielectrics are the preferred materials for energy storage capacitors owing to their high breakdown strength and low loss, [6][7][8][9][10][11][12][13][14][15][16] their performance typically optimized for operation at ambient temperature declines significantly with the increase of working temperatures. [17][18][19][20] For example, the discharge efficiency (η, η = U e /U o × 100%, U e : discharged energy density, U o : stored energy density) of biaxially oriented polypropylene (BOPP) films, which is the best commercially available dielectric polymer, decreases steeply from 96.2% to 87.4% and 68.5% with increasing temperature from 25 o C to 80 o C and 120 o C, respectively, at an applied field of 400 MV m -1 .…”

Section: Introductionmentioning

confidence: 99%

Crosslinked fluoropolymers exhibiting superior high-temperature energy density and charge–discharge efficiency

Gadinski

Huang

et al. 2020

Energy Environ. Sci.

232

215

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The electrification of transport requires dielectric materials capable of operating efficiently at high temperatures to meet the increasing demand of electrical energy storage at extreme conditions. Current high-temperature dielectric polymers rely on the incorporation of wide bandgap inorganic fillers to restrain electrical conduction and achieve high efficiencies at elevated temperatures. Here, we report a new class of all-polymer based high-temperature dielectric materials prepared from crosslinking of melt-processable fluoropolymers. The crosslinked polymers exhibit larger discharged energy densities and greater charge-discharge efficiencies along with excellent breakdown strength and cyclic stability at elevated temperatures when compared to the current dielectric polymers. The origins of the marked improvement in the hightemperature capacitive performance are traced to efficient charge-trapping by a range of the molecular trapping centers resulted from the crosslinked structures. In addition, the implementation of melt-extrudable polymers would enable scalable processing that is compatible with the current fabrication techniques used for polymer dielectrics, which is in sharp contrast to the dielectric polymer composites with inorganic fillers.

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“…A decreasing permittivity and dielectric loss with increasing frequency, has been observed for thin lms of BaTiO 3 -polymer core-shell particles with even lower ac conductivities than reported here. 41,42 In this work the measurements were conducted on pressed powders and the presence of lowpermittivity air between the inter-particle spaces can lower the measured effective permittivity and give some inaccuracy. However, the dielectric losses for all the OPZ@BaTiO 3 were surprisingly low.…”

Section: Dielectric Properties Of the Core-shell Particlesmentioning

confidence: 99%

Functionalization of BaTiO₃ nanoparticles with electron insulating and conducting organophosphazene-based hybrid materials

et al. 2017

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Novel core-shell structured organophosphazene (OPZ) coated BaTiO 3 nanoparticles (OPZ@BaTiO 3 ) were produced via a facile and rapid one-step nucleophilic substitution reaction in ambient conditions. The morphology, structure and textural properties of the core-shell nanoparticles were analysed via electron microscopy, spectroscopy, thermogravimetry and porosimetry, and the dielectric properties were evaluated by impedance spectroscopy. The thickness of the cross-linked OPZ shell was readily tailored by varying the weight ratio of the OPZ monomers to BaTiO 3 , which in turn affected the relative permittivity and the frequency dependence of the OPZ/BaTiO 3 particles. A subsequent carbonisation treatment of the OPZ@BaTiO 3 at 700 C transformed the polymeric OPZ shell to a microporous carbonaceous shell, which dramatically increased the electrical conductivity of the particles.Organophosphazene chemistry offers a facile route to functionalise BaTiO 3 nanoparticles without any pre-treatment, and generate a range of core-shell BaTiO 3 nanoparticles with tailored dielectric and electrically conductive properties that can be used as active fillers for polymer based nanocomposites and energy storage applications. The effectiveness and advantages of OPZ chemistry over other reported methods in forming core-shell particles are demonstrated. Fig. 2 SEM images of (a) the commercial BaTiO 3 particles after sonication, (b) OPZ@BaTiO 3 -0.25, (c) OPZ@BaTiO 3 -0.5, (d) OPZ@BaTiO 3 -1, (e) OPZ@BaTiO 3 -4. Scale bar at 500 nm. (f) Representative spectra from EDX elemental analysis. This journal isFig. 7 (a) AC conductivity of the OPZ@BaTiO 3 and C@BTO samples and comparison with the dense OPZ, (b) phase angle of OPZ@BaTiO 3 and C@BTO samples. Phase angle approaching 0 deg indicates conductive behavior, approaching 90 deg indicates capacitative behavior, (c) relative permittivity of the OPZ@BaTiO 3 samples and comparison with the dense OPZ nanospheres. (d) Dielectric loss of the OPZ@BaTiO 3 samples and comparison with the dense OPZ nanospheres.This journal is

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Superhard three-dimensional B₃N₄ with two-dimensional metallicity

Abstract: Using first-principles calculations, we uncovered that t-B3N4 is metastable at ambient pressure, but becomes stable under high pressure. The metallic conduction of t-B3N4 is interrupted by the insulated boron sheets stacked along the c axis, giving rise to its 2D metallicity.

Cited by 19 publications

References 25 publications

Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Crosslinked fluoropolymers exhibiting superior high-temperature energy density and charge–discharge efficiency

Functionalization of BaTiO₃ nanoparticles with electron insulating and conducting organophosphazene-based hybrid materials

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Superhard three-dimensional B3N4 with two-dimensional metallicity

Abstract: Using first-principles calculations, we uncovered that t-B3N4 is metastable at ambient pressure, but becomes stable under high pressure. The metallic conduction of t-B3N4 is interrupted by the insulated boron sheets stacked along the c axis, giving rise to its 2D metallicity.

Cited by 19 publications

References 25 publications

Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Poly(methyl methacrylate)-grafted ZnO nanocomposites with variable dielectric constants by UV light irradiation

Crosslinked fluoropolymers exhibiting superior high-temperature energy density and charge–discharge efficiency

Functionalization of BaTiO3 nanoparticles with electron insulating and conducting organophosphazene-based hybrid materials

Contact Info

Product

Resources

About

Superhard three-dimensional B₃N₄ with two-dimensional metallicity

Functionalization of BaTiO₃ nanoparticles with electron insulating and conducting organophosphazene-based hybrid materials