A comprehensive review: optimization of microwave dielectric performance in ABX3- type complex metal oxides

Abstract With the advent of 5G/6G technologies and the continued advancement of communication systems, the shift toward low-loss microwave dielectrics has become essential. In this context, inorganic complex microwave dielectric materials offer the potential for various combinations and partial or complete substitutions, resulting in a wide range of new compounds. The fabrication method, dopant concentration, and crystal structure significantly influence the electronic properties of these materials. Importantly, this work focuses on several recently reported titanium-, silicon-, and zirconium-based materials, such as CaTiO₃, MgTiO₃, MgSiO₃, and CaZrO₃. However, comprehensive review studies on microwave dielectric materials remain limited, and the fundamental relationship between their crystal structures and dielectric properties is still not fully understood. This review highlights microstructural characteristics-particularly grain size and density-in complex hybrid metal oxides. Additionally, it provides a comprehensive analysis of microwave dielectric properties, with a focus on ABX3 perovskites for electronic applications such as 5G/6G communication systems. To the best of our knowledge, there is no extensive reviews connecting the crystal structures of diverse hybrid complex metal oxides with their corresponding microwave dielectric properties.