Crystallographic shearing effects on the broadband dielectric response of rutile TiO _2– <i> _x </i> ceramics

Abstract Dielectric ceramics play an important role in electromagnetic wave regulation and energy storage. Among them, rutile TiO 2 ceramics have received considerable attention for their outstanding dielectric properties, including the giant permittivity at low frequencies and the low loss in the microwave‐terahertz bands. Controlling the dielectric loss, which is generally considered to be affected by defects, is the key to the design of dielectrics. However, except for point defects like oxygen vacancies, the understanding of the influential mechanism of high‐dimensional defects such as dislocations and stacking faults on the dielectric response is nearly blank. Herein, a series of disordered crystallographic shearing is discovered in rutile TiO 2– x ceramics. Two types of crystallographic shear planes (CSPs) with different structures and micromorphologies are obtained by simply adjusting the sintering temperature. The CSPs dominate the high dielectric loss in the microwave‐terahertz band by changing the phonon vibration behavior. Specifically, the submicron zones formed by {020} CSPs induce strong interfacial polarization at low frequencies, leading to a giant permittivity around 3000. The crystallographic shearing presents negligible changes with other sintering parameters, especially the oxygen partial pressure, indicating an independent behavior with oxygen vacancies. The crystallographic shearing effects on the broadband dielectric properties of rutile TiO 2– x ceramics revealed in this work provide a theoretical guideline for further studies in the dielectric properties of transition metal oxides.