In this work, Zn-Ni co-modified LiMg 0.9 Zn 0.1- x Ni x PO 4 ( x = 0–0.1) microwave dielectric ceramics were fabricated using a solid state synthesis route. Rietveld refinement of the XRD data revealed that all ceramic samples have formed a single phase with olivine structure. SEM images showed that the samples have a dense microstructure, that agrees with the measured relative density of 97.73 %. Based on the complex chemical bond theory, Raman and infrared reflectance spectra, we postulate that ε r is mainly affected by the ionic polarizability, lattice and bond energy, while P-O bond plays a decisive role in Q×f and τ f value. Optimum properties of Q×f ~ 153,500 GHz, ε r ~ 7.13 and τ f ~ −59 ppm/°C were achieved for the composition LiMg 0.9 Zn 0.06 Ni 0.04 PO 4 sintered at 875 ℃ for 2 h. This set of properties makes these ceramics an excellent candidate for LTCC, wave-guide filters and antennas for 5 G/6 G communication applications. 

High Q×f values of Zn-Ni co-modified LiMg0.9Zn0.1-Ni PO4 microwave dielectric ceramics for 5G/6G LTCC modules

Cordierite-based dielectric ceramics with a lower dielectric constant would have significant application potential as dielectric resonator and filter materials for future ultra-low-latency 5G/6G millimeter-wave and terahertz communication. In this article, the phase structure, microstructure and microwave dielectric properties of Mg2Al4–2x(Mn0.5Zn0.5)2xSi5O18 (0 ≤ x ≤ 0.3) ceramics are studied by crystal structure refinement, scanning electron microscope (SEM), the theory of complex chemical bonds and infrared reflectance spectrum. Meanwhile, complex double-ions coordinated substitution and two-phase complex methods were used to improve its Q×f value and adjust its temperature coefficient. The Q×f values of Mg2Al4–2x(Mn0.5Zn0.5)2xSi5O18 single-phase ceramics are increased from 45,000 [email protected] GHz (x = 0) to 150,500 [email protected] GHz (x = 0.15) by replacing Al3+ with Zn2+-Mn4+. The positive frequency temperature coefficient additive TiO2 is used to prepare the temperature stable Mg2Al3.7(Mn0.5Zn0.5)0.3Si5O18-ywt%TiO2 composite ceramic. The composite ceramic of Mg2Al3.7(Mn0.5Zn0.5)0.3Si5O18-ywt%TiO2 (8.7 wt% ≤ y ≤ 10.6 wt%) presents the near-zero frequency temperature coefficient at 1225 °C sintering temperature: εr = 5.68, Q×f = 58,040 GHz, τf = −3.1 ppm/°C (y = 8.7 wt%) and εr = 5.82, Q×f = 47,020 GHz, τf = +2.4 ppm/°C (y = 10.6 wt%). These findings demonstrate promising application prospects for 5 G and future microwave and millimeter-wave wireless communication technologies. 

High-Qf value and temperature stable Zn2+-Mn4+ cooperated modified cordierite-based microwave and millimeter-wave dielectric ceramics

Effects of Ionic Coordination Bonding on Microwave Dielectric Properties of Y2CaBGa4O12 (B = Zr, Sn) Garnets

Acrylamide-modified polyvinyl alcohol and combined with graphene oxide for low dielectric constant composite films

Crystal structure, chemical bond characteristics, and microwave dielectric properties of novel Sr2CaMoO6 ceramic at different sintering temperatures

5G and forthcoming 6G communication systems require dielectric ceramics with low relative permittivity (εr) and near-zero temperature coefficient of resonant frequency (τf) for the lower part of the microwave (MW) band and at sub-Terahertz. Mg2Al4Si5O18 (MAS) ceramics are promising candidates due to their low εr (~ 6) and high-quality factor (Q×f > 40,000 GHz) but have a large τf. In this study, 5.5 wt% TiO2 (MAS-T5.5) was used to adjust τf of MAS to −2.8 ppm/℃ whilst retaining low εr (5.24) and good Q×f (33,400 GHz), properties consistent with those obtained by infrared reflectance. A demonstrator microstrip patch antenna with gain 4.92 dBi and 76.3% efficiency was fabricated from MAS-T5.5. 

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Low permittivity cordierite-based microwave dielectric ceramics for 5G/6G telecommunications

Formulations for Conductor-Dielectric Periodic thin film is derived and used to compute millimeter wave reflectivity. The finite conductivity and nonzero thickness of grid, in addition to the influence of substrate can be take into account with invoking no basis functions.

Wen-jun Li

Papers

Low permittivity cordierite-based microwave dielectric ceramics for 5G/6G telecommunications

Millimeter Wave Reflectivity of Conductor-Dielectric Periodic Thin Film