Antipolar Domain Engineering and Optimized Dielectric Properties of Antiferroelectric CaTiSiO ₅ Ceramics

ABSTRACT

The unique antipolar structure of titanite‐type CaTiSiO ₅ ‐based ceramics has attracted considerable attention, with certain compositions confirmed to be antiferroelectric. Due to their low relative permittivity, CaTiSiO ₅ ceramics hold promise for electrically tunable applications, but their reliability and high dielectric loss under DC bias must be improved. Herein, the introduction of Mn in CaTiSiO ₅ slightly perturbs the long‐range ordered antipolar TiO ₆ chains, creating antipolar microdomains at a scale of tens of nanometers. This structural adjustment markedly lowers the dielectric loss under DC bias without substantially sacrificing the tuning performance. Moreover, Mn doping promotes a carrier migration barrier at the electrode–ceramic interface, which raises the breakdown strength. With 2 mol% MnO ₂ addition, the ceramic sample achieves a tunability above 50% under 250 kV/cm and maintains tan δ < 0.002 at 100 kHz. Compared with CaTiSiO ₅ ‐SiO ₂ composite ceramics, the domain‐engineering strategy outperforms conventional composite approaches for reducing dielectric loss. Thus, tailoring antipolar domains offers an effective route to enhance the overall properties of antiferroelectric tunable ceramics, providing a new perspective for developing next‐generation tunable materials and devices.