The rapid advancement of 5G/6G communication technologies imposes ever-increasing demands on microwave dielectric ceramics (MWDCs). However, it remains challenging to simultaneously achieve good temperature stability and high Q×f values. Metamaterials with artificially designed structures exhibit extraordinary properties, and metamaterialogy holds great potential for advancing conventional materials. Inspired by this paradigm, an artificial core-shell cofired architecture was designed to realize high-performance MWDCs. The architecture employed the Zn_1.01Nb₂O₆ (ZNO) matrix as the shell and positive-τ_f compensators, including TiO₂ (TO), CaTiO₃ (CTO), or SrTiO₃ (STO), in either green or pre-sintered states, as cores. The τ_f values of all the core-shell samples were effectively tuned to near zero while high Q×f values were retained. Specifically, the ZNO-TO core-shell ceramic with a 1.43 wt% pre-sintered TO core exhibited εᵣ ~ 25.32, Q×f ~ 119,100 GHz, and τ_f ~ -4.8 ppm/°C, while the temperature-stable counterparts using the CTO or STO cores retained Q×f ≥ 67,800 GHz. Furthermore, HFSS simulation of a cylindrical dielectric resonator antenna (CDRA) based on the optimized ZNO-TO core-shell ceramic predicted favorable impedance matching (VSWR ~ 1.015), radiation efficiency above 90%, and a peak realized gain of 6.13 dBi at 4.31 GHz. It preliminarily demonstrates the feasibility of CDRA applications. The artificial core-shell architecture provides a general strategy for synergistically optimizing microwave dielectric properties by tailoring the electric-field participation and confining heterogeneous interfacial reactions, which is beneficial to developing high-performance MWDCs required for next-generation communication technologies.

The design of microstructures is essential for tailoring the microwave dielectric properties of ceramics, yet the structure–property relationships in tetragonal scheelite-structured ceramics remain insufficiently understood. In this study, first-principles calculations combined with experiments were used to systematically investigate the interrelations among the sintering behavior, crystal structure, electrical characteristics, bond characteristics, and dielectric performance of NaSrLnMo₃O₁₂ (Ln = Ce, Pr, Eu, Y, and Yb) ceramics. All the compositions crystallized into a tetragonal scheelite structure (space group I4₁/a) and exhibited favorable dielectric properties with optimal sintering temperatures of 775–925 °C, ε_r = 9.8–10.34, Q×f = 30,487–69,445 GHz, and τ_f = −20.55–(−44.24) ppm/°C. The increase in ε_r originated mainly from the increased ionicity of the Na/Sr/Ln–O bonds, whereas the increase in Q×f was attributed to the increased lattice energy of the Mo–O bonds, increased bond valence, and reduced ionic/electricity disorder. The negative shift in τ_f was primarily linked to the increased linear thermal expansion coefficient α_L of the Na/Sr/Ln–O bonds. Furthermore, the electrical characteristics and relaxation mechanisms were examined, and the dielectric response in the terahertz range was confirmed. Finally, NaSrCeMo₃O₁₂ was employed to design and fabricate two antenna devices, verifying its potential for high-frequency communication. This work provides a systematic understanding of the role of Ln in optimizing the dielectric properties of tetragonal scheelite ceramics and clarifies the microscopic mechanisms underlying their performance.