Ni-Co Complex Ionic Synergistically Modifying Octahedron Lattice of Cordierite Ceramics for the Application of 5G Microwave-Millimeter-wave Antennas.

In this work, phase-pure Mg(NiCo)AlSiO (0 ≤ ≤ 1) ceramics were synthesized by a high-temperature solid-state method. On the basis of Rietveld refinement data of X-ray powder diffraction and Phillips-Vechten-Levine theory, the atomic ionicity, lattice energy, and bond energy of the compound were calculated to explore their influence on the microwave dielectric properties of ceramics. The MgNiCoAlSiO ( = 0.5) ceramic exhibited the best microwave dielectric properties: = 4.44, = 73 539 GHz@13 GHz, and τ = -23.9 ppm/°C. (NiCo) complex ionic doping, compared with only Ni or Co, is beneficial for improving the symmetry of [SiAlO] hexagonal rings and reducing distortion. Subsequently, 8 wt % TiO was added to MgNiCoAlSiO, resulting in a near-zero and high values for the composite ceramic, with = 5.22, = 58 449 GHz@13 GHz, and τ = -2.06 ppm/°C. Finally, a 5G millimeter-wave antenna with a central operating frequency of 25.52 GHz was designed and fabricated using the MgNiCoAlSiO-8 wt % TiO ceramics. Operating in the 24.7-26.0 GHz range, it demonstrated favorable radiation characteristics with a simulated efficiency of 85.2% and a gain of 4.58 dBi. The antenna's performance confirms the high potential of the cordierite composite for application in 5G communication systems.