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Start date: 2025Subject: search.filters.subject.Low dielectric loss

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    Process-structure-property relationships in low-temperature microwave dielectric ceramics: from glass-assisted sintering to cold sintering for 5G/6G devices
    (2026-12-01)
    Pulphol, Phieraya
    ;
    Tang, Ying
    ;
    Fang, Liang
    ;
    Vittayakorn, Wanwilai
    ;
    Sukkha, Usa
    With the rapid advancement of wireless communication from 5G to 6G, a pressing need has emerged for microwave dielectric ceramics with excellent performance at reduced processing temperatures, compatible with low-temperature co-fired ceramic technology. This review traces historical milestones and highlights modern design strategies for achieving optimum dielectric constant, ultra-low dielectric loss, and near-zero temperature coefficient of resonant frequency. Special emphasis is placed on recent advances in low-temperature densification routes, including sintering aids, intrinsically low-sintering-temperature ceramic families, and novel techniques like the cold sintering process. This review provides a critical analysis of the performance trade-offs inherent to each strategy, addressing the persistent challenges in achieving ultra-low loss. Furthermore, we highlight the paradigm shift toward a holistic, multifunctional design imperative for 6G systems. Finally, the transformative potential of cross-disciplinary approaches, particularly AI-assisted discovery, and computational modeling, is discussed as a key enabler for accelerating the design of next-generation, high-performance, and sustainable LTCC-compatible materials.
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    High-entropy gallium-based garnet microwave dielectric ceramics with low loss for C-band dielectric resonator antenna application
    (2025-11-01)
    Wen, Xinyang
    ;
    Xiang, Huaicheng
    ;
    Gu, Xiaolong
    ;
    Pulphol, Phieraya
    ;
    Vittayakorn, Naratip
    In this work, (Y<inf>0.5</inf> Nd<inf>0.5</inf> Sm<inf>0.5</inf> Eu<inf>0.5</inf> Ho<inf>0.5</inf> Yb<inf>0.5</inf> )Ga<inf>5</inf> O<inf>12</inf> high-entropy ceramic with a cubic garnet structure was designed and synthesized via a solid-state reaction method. Through the high-entropy regulation of the oxygen dodecahedron, the bond strength increases, the cation's bond valence approaches the ideal value, and the structural stability improves, thereby promoting the Q × f value. Low dielectric loss (Q × f = 130,100 GHz) was obtained in the high-entropy ceramic (Y<inf>0.5</inf> Nd<inf>0.5</inf> Sm<inf>0.5</inf> Eu<inf>0.5</inf> Ho<inf>0.5</inf> Yb<inf>0.5</inf> )Ga<inf>5</inf> O<inf>12</inf> , which exhibited a low relative permittivity (ε<inf>r</inf> ) of 12.36, a negative temperature coefficient of resonant frequency (τ<inf>f</inf> ) of −66.37 ppm/°C, and a high flexural strength of 229.68 MPa. Furthermore, a cylindrical dielectric resonator antenna (CDRA) was designed featuring high radiation efficiency (>90 %) and stable gain (5.91–5.97 dBi) within a 255 MHz bandwidth, showing promising application prospects in the C-band. This work indicates that the high-entropy strategy is feasible for the design of high-performance microwave dielectric ceramics.