CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Meng Fei Zhou,Cheng Chao Hu,Jian Bing Yin,Yu Jiang,Bing Liu,Kai Xin Song
SrF 2 is a promising low- ε r fluoride with outstanding microwave dielectric properties , while densification of SrF 2 ceramics is challenging via traditional thermal sintering (TTS). In this work, dense SrF 2 ceramics with 93.4%–97.2% relative density have been obtained via cold sintering (300 MPa–900 MPa, 150 °C, 1 h) and subsequent post-annealing at 950 °C/3 h. The pretreated cold sintering process is beneficial for microstructure optimization, where the maximum Qf value (62,037 GHz) is obtained at 750 MPa, nearly three times higher than the TTS sample (21,080 GHz). An ultra-low dielectric constant ( ε r ) of 5.94 is simultaneously obtained, together with a temperature coefficient of resonant frequency τ f = −78.26 ppm/°C. Good chemical compatibility between SrF 2 ceramics and silver is verified, indicating great promise for their use in LTCC technology. Moreover, the low- ε r and high Qf values of the cold sintering optimized SrF 2 ceramics suggest great potential in the 5G millimeter-wave antenna systems. A SrF 2 -based dielectric resonator antenna is designed and fabricated, which resonates at the desired 24.5 GHz and exhibits an outstanding S 11 of −43.95 dB and a broad bandwidth of 4.51 GHz.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 40
·14359-14370
·
IF 7.393
Lingxia Li,Xubin Wang,Weijia Luo,Shun Wang,Tian Yang,Ji Zhou
Miniaturization, power dissipation and temperature stability are the most critical factors restricting the microwave use of ceramic-based devices. Balancing them, especially for the ceramics with high dielectric constant, is a great challenge. Herein, a new strategy by trivalent ion (Al3+ and Ga3+) co-substitution is put forward in tungsten bronze structural Ba4Nd9.33Ti18O54 ceramics for millimeter-wave metamaterials, and a nearly 40% increase in Qf values with stable temperature characteristics is obtained. The crystal symmetry, morphology and the vibration modes are characterized by XRD, EDS and Raman spectroscopy, suggesting the varied internal strain and oxygen octahedron tilt from the mismatch of different cations. The best performance of Ba4Nd9.33Ti18−x(Al0.4Ga0.6)xO54−0.5x (BNT-AGx) is observed when x is 2.4: εr = 67.71, Qf = 13 675 GHz, τf = +4.4 ppm °C−1. Considering the dispersion relationship of BNT-AGx ceramics further, the structure of BNT-AGx metamaterials is uniquely designed, and the sub-wavelength BNT-AGx blocks are also fabricated to demonstrate the frequency selection filtering function with high temperature stability at the millimeter-wave band (>30 GHz), which is of great significance to achieve some eMBB (Enhanced Mobile Broadband) scenes of 5G (the 5th Generation) technology, from a metal loaded cavity to free space.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 104
·期 9
·4659-4668
·
IF 3.784
Chao Du,Mao-Sen Fu,Di Zhou,Huan-Huan Guo,He-Tuo Chen,Jian Zhang,Jun-Ping Wang,Shao-Fei Wang,Hai-Wen Liu,Wen-Feng Liu,Long Li,Zhuo Xu
Microwave dielectric ceramics are considered to be one of the key materials for dielectric resonators (DR) and have very broad application prospects in the fifth generation (5G) mobile communication system. Here we have prepared high-quality factor Y 3 Al 5 O 12 (YAG) transparent dielectric ceramics using high-purity α-Al 2 O 3 and Y 2 O 3 powders by cold isostatic pressing of the vacuum sintered with tungsten meshes as the heating elements. Optimum relative permittivity ( ) ~10.53, quality factor Q × f (Q = 1/dielectric loss, f = resonant frequency) ~95, 270 GHz (at =7.37 GHz), and temperature coefficient of resonant frequency (TCF) ~ −51.7 ppm °C −1 were obtained at a sintering temperature of 1780°C for 12 h. For the first time, YAG transparent ceramic dielectric resonator antenna (DRA) is designed as a dominant mode and a higher-order mode using the aperture coupling feeding configuration excitation. The proposed transparent dielectric ceramic DRA can provide a broad impedance bandwidth of 4.193 GHz (ranging from 21.90 to 26.09 GHz) for S 11 < −10 dB, radiation efficiency of 92.1%, and compact DR unit. The proposed DRA can be used potentially as a 5G millimeter (mm)-wave multiple-input-multiple-output (MIMO) antenna unit.
研究领域:
材料科学
·
通信工程
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Juan Liu,Bing Liu,Cheng Chao Hu,Qing Wei Zhou,Kai Xin Song
(1– x )BaV 2 O 6 - x LiF ( x = 0.025, 0.05, 0.10, 0.15) ceramics with an ultra-low sintering temperature of 475 °C were synthesized using the standard solid-state reaction method. The ceramics demonstrated a remarkable enhancement in the quality factor ( Qf ), reaching a maximum value of 16,800 GHz at x = 0.10, which is 5.6 times higher than that of pure BaV 2 O 6 ceramics obtained in this work. A near-zero temperature coefficient of resonant frequency ( τ f = 1.44 ppm/°C) was simultaneously achieved, together with a dielectric constant ε r of 11.54. Additionally, the chemical compatibility between the present ceramics and the Al electrode was confirmed. Moreover, a millimeter-wave antenna with an excellent S 11 value of −50.3 dB, and a large bandwidth of 3.44 GHz was fabricated using the 0.9BaV 2 O 6 -0.1LiF ceramic as the dielectric resonator . These results highlight the potential application prospects of (1– x )BaV 2 O 6 - x LiF ceramics in the ultra-low temperature co-fired ceramic technology and 5 G millimeter-wave antennas.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）