Ultralow-Permittivity and Temperature-Stable Ba1- xCaxMg2Al6Si9O30 Dielectric Ceramics for C-Band Patch Antenna Applications

Kang Du; Mengdie Zhou; Chengyun Li; Changzhi Yin; Yiyang Cai; Mingfei Cheng; Wei Zhu; Guochao Wei; Shengxiang Wang; Wen Lei

doi:10.1021/acsami.4c00652

Ultralow-Permittivity and Temperature-Stable Ba_{1- x}Ca_xMg₂Al₆Si₉O₃₀ Dielectric Ceramics for C-Band Patch Antenna Applications

ACS Appl Mater Interfaces. 2024 Apr 24. doi: 10.1021/acsami.4c00652. Online ahead of print.

Authors

Kang Du^{1

2}, Mengdie Zhou¹, Chengyun Li¹, Changzhi Yin³, Yiyang Cai³, Mingfei Cheng³, Wei Zhu¹, Guochao Wei¹, Shengxiang Wang^{1

2}, Wen Lei^{3

4}

Affiliations

¹ School of Mathematical and Physical Sciences, Wuhan Textile University, Wuhan 430200, P. R. China.
² State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430200, P. R. China.
³ School of Optical and Electronic Information, Key Lab of Functional Materials for Electronic Information (B) of MOE, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
⁴ Wenzhou Key Laboratory of Microwave Communication Materials and Devices, Wenzhou Advanced Manufacturing Institute of HUST, Wenzhou 325035, P. R. China.

PMID: 38655785
DOI: 10.1021/acsami.4c00652

Abstract

Ca-substituted Ba_1-xCa_xMg₂Al₆Si₉O₃₀ ceramics were prepared to explore the relationships among their crystal structural parameters, phase compositions, dielectric properties, and coefficients of thermal expansion and applications in C-band antenna. The maximum solubility of Ba_1-xCa_xMg₂Al₆Si₉O₃₀ was located at x = 0.25, and Ba_1-xCa_xMg₂Al₆Si₉O₃₀ ceramics (0 ≤ x ≤ 0.25) crystallized in the space group P6/mcc. In Ba_1-xCa_xMg₂Al₆Si₉O₃₀ single-phase ceramics, ε_r was dominated by ionic polarizability and "rattling effects" of Ba²⁺ and Al(2)³⁺; Q × f was controlled by the roundness of [Si₄Al₂O₁₈] inner rings and total lattice energy; and τ_f was affected by the bond valence of Si/Al(1)-O(1). Notably, the low average coefficients of thermal expansion (2.668 ppm/°C) at -150 °C ≤ T ≤ 850 °C and near-zero coefficients of thermal expansion (1.254 ppm/°C) at -150 °C ≤ T ≤ 260 °C were achieved for the Ba_1-xCa_xMg₂Al₆Si₉O₃₀ (x = 0.1) ceramic. Optimum microwave and terahertz dielectric properties were obtained for the Ba_1-xCa_xMg₂Al₆Si₉O₃₀ (x = 0.1) ceramic with ε_r = 5.80, Q × f = 31,174 at 13.99 GHz, τ_f = -7.10 ppm/°C, and ε_r = 5.71-5.85 at 0.2 THz ≤ f ≤ 1.0 THz. Also, the Ba_1-xCa_xMg₂Al₆Si₉O₃₀ (x = 0.1) ceramic substrate had been designed as a C-band patch antenna with a high simulated radiation efficiency (87.76%) and gain (6.30 dBi) at 7.70 GHz (|S₁₁| = -38.41 dB).

Keywords: Ba1−xCaxMg2Al6Si9O30 ceramic; C-band dielectric patch antenna; low εr and CTE; microwave and terahertz dielectric properties; self-near-zero τf.