JOURNAL OF THE AMERICAN CERAMIC SOCIETY
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2025
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IF 3.8
Gaofeng Shao,Yu Sun,Gaoyuan Yu,Weiquan Huang,Liqun Guo,Xiaogu Huang
Polymer-derived ceramics (PDCs), known for their exceptional thermal stability and adjustable dielectric characteristics, show great promise in electromagnetic wave absorption applications under extreme temperature conditions. Their multiphase and multi-heterointerface structures also enable effective low-frequency absorption for 5G applications, a crucial yet underexplored capability. In this study, nickel-modified SiCN (SiCN/Ni) ceramics were synthesized through coordination crosslinking of trace amounts of nickel-based metal-organic framework (Ni-MOF) with polysilazane precursor, followed by high-temperature pyrolysis. The investigation reveals that Ni-MOF enables the formation of both dielectric and magnetic loss components, specifically SiC nanocrystals, free carbon, and Ni 2 Si nanocrystals, during the synthesis process at reduced temperature conditions. The coexistence of electromagnetic-transparent and absorbing phases enhances impedance matching. The heterogeneous nanodomains create multiple interfaces, induce significant lattice strain, and produce abundant structural defects, which together enhance interfacial and dipole polarization effects. Notably, the optimized SiCN/Ni ceramic exhibits exceptional microwave absorption performance at low frequency, achieving a minimum reflection loss of –46.1 dB at 5.28 GHz. The low-frequency absorption bandwidths reach 0.76 and 1.0 GHz at thicknesses of 4.0 and 5.0 mm, fully covering both the n 78 band (3.3–3.8 GHz) and n 79 band (4.4–5.0 GHz) used in 5G communications. These findings present new opportunities for developing advanced lower-frequency absorbers based on dielectric PDCs.
研究领域:
材料科学
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电磁学
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DOI
高影响因子
Crystals
·
2022
·Vol. 12
·期 11
·1608
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IF 2.67
Zijun Ye,Yu Jiang,Minmin Mao,Zhiyu Xiu,Mengjiao Chi,Guofa Wu,Bing Liu,Dawei Wang,Bin Yang,Kaixin Song
In this work, Y2.95R0.05MgAl3SiO12(R = Yb, Y, Dy, Eu, Sm) microwave single-phase dielectric ceramics were successfully prepared via a conventional ceramic sintering technology by doping a series of rare earth elements (Yb, Y, Dy, Eu, Sm) with different ionic radii for the first time. The effects of A-sites occupied by rare earth elements on the microwave dielectric properties of Y2.95R0.05MgAl3SiO12were studied using crystal structure refinement, a scanning electron microscope (SEM), bond valence theory, P-V-L theory, and infrared reflection spectroscopy. It was found that the ionicity of the Y-O bond, the lattice energy, the bond energy, and the bond valance of the Al(Tet)-O bond had important effects on the microwave dielectric properties. Particularly, the optimum microwave dielectric properties,εr= 9.68,Q×f= 68,866 GHz, andτf= −35.8 ppm/°C, were obtained for Y2.95Dy0.05MgAl3SiO12when sintered at 1575 °C for 6 h, displaying its potential for 5G communication.Keywords:garnet;microwave dielectric properties;P–V–L theory;infrared reflection spectroscopy
研究领域:
材料科学
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通信工程
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DOI
高影响因子
Crystals
·
2023
·Vol. 13
·期 9
·1296
·
IF 2.7
Yan Wang,Jiajing Li,Haipeng Zhu,Qilei Wang,Tulai Sun,Tao Ni,Yanghong Lin,Yu Liu,Minmin Mao,Ji Hu,Bing Liu,Hadi Barzegar Bafrooei,Zhongyan Ma,Yingjie Ren,Feng Shi,Ehsan Taheri-Nassaj,Dawei Wang,Kaixin Song
Mg2SiO4and MgSiO3ceramics with superior microwave dielectric properties are considered to be promising candidates for 5G applications. However, a slight deviation from the stoichiometric Mg/Si ratio will significantly influence their microwave dielectric properties, which will hinder their practical applications. In this work, thexMgO-SiO2(x= 1~2) ceramics were synthesized by a solid-state reaction method. The influence of the Mg/Si ratioxon the crystalline phase, microstructure, and microwave dielectric properties was investigated through X-ray diffraction (XRD), a scanning electron microscope (SEM), and the resonant cavity method. The XRD patterns revealed the coexistence of Mg2SiO4and MgSiO3within thexrange of 1~2, which was further demonstrated by the energy-dispersive X-ray spectra. The SEM images show a typical polycrystalline morphology of ceramics with an inhomogeneous grain size distribution. It is found that the microwave dielectric properties fluctuate at both sides of thexrange while those remain relatively stable with minor changes at the intermediate components, indicating an obvious low composition dependence helpful for practical applications. Further, a demonstrator of a microstrip patch antenna for 5G applications using the 1.5MgO-SiO2ceramic was designed and fabricated, and a return loss of −16.2 dB was demonstrated, which demonstrated the potential applications.Keywords:MgO-SiO2systems;5G application;microwave dielectric ceramics;phase composition
研究领域:
材料科学
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电子工程
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DOI
高影响因子
POLYMER COMPOSITES
·
2024
·
IF 4.8
Lingyuan Liao,Wenhong Ruan,Mingqiu Zhang,Weihao Li,Musong Lin
Incorporation of boron nitride (BN) into polymers is a promising method to obtain composites with high thermal conductivity, low dielectric constant ( D k ), and dielectric loss ( D f ), while the practical applications are limited by the poor interface between BN and polymer because of surface energy mismatch and absence of covalent bond connection between them. Herein, polydopamine (PDA) with good adhesion is deposited onto the BN. Then, a different amount of silane coupling agent containing vinyl reactive groups is grafted onto PDA-coated BN. In this way, the surface energy of modified BN (m-BN) can be adjusted to ensure BN contacts well with polymers. Moreover, reactive groups were introduced on BN for further reaction. Subsequently, covalent bonds between the m-BN and the polyphenylene oxide (PPO) were established in situ during the curing process. The effects of the m-BN surface energy on interface quality and thermal conductivity of composites are investigated. The m-BN/PPO composite achieves a through-plane thermal conductivity of 5.87 W/m · K and a low D f value of 1.53 × 10 −3 , as well as a low coefficient of thermal expansion (CTE) value (7.8 ppm/K) when the m-BN loading is 32.6 vol%. This research provides a simple and efficient strategy for fabricating high-performance composites for high-frequency applications. Highlights Hexagonal boron nitride was modified successfully by combining non-covalent and covalent modifications. Regulating surface energy and establishing covalent bonds enhances interface interaction between BN and polyphenylene oxide. Modified BN/polyphenylene oxide composites display improvements in thermal conductivity and dimensional stability as well as dielectric loss. Provides a feasible strategy for designing polymer composites with high thermal conductivity, dimensional stability, and low dielectric loss for 5G applications.
研究领域:
材料科学
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高分子化学
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电子材料
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DOI
高影响因子
危险品化学品经营许可证（带存储）