(Li_0.4Co_0.2Ni_0.2Cu_0.2Zn_0.2)WO₄: A Novel High-Entropy Wolframite Ceramic with Tailored Microwave Dielectric Properties

(Li_0.4Co_0.2Ni_0.2Cu_0.2Zn_0.2)WO₄ high-entropy ceramics were prepared by a conventional solid-state reaction route. This study thoroughly explores the interrelationships between their crystal structure, bond properties, and microwave dielectric characteristics. X-ray diffraction analysis verified that all specimens crystallized in a single-phase ZnWO₄-type structure. According to Rietveld refinement of the XRD data, the lattice parameters are affected by the ionic radii of the constituent elements, confirming their dissolution and random distribution at Zn sites. Relative density exhibited a strong dependence on sintering temperature. Bonding analysis highlights the crucial role of the W-O bond in governing the dielectric response of the (Li_0.4Co_0.2Ni_0.2Cu_0.2Zn_0.2)WO₄ (LCNCZW) ceramics. Moreover, sinterability can be improved through optimizing the sintering process. Notably, samples sintered at 850 °C attained suitable dielectric performance, characterized by εᵣ = 11.697 ± 0.204, Q × f = 23,851 ± 0.126 GHz, and τ_f = 21.335 ± 0.232 ppm/°C. These results demonstrate that high-entropy design can effectively improve the sinterability and microwave dielectric performance of wolframite-type ceramics, offering a promising strategy for the development of microwave dielectric ceramics for communication devices.