Antipolar Domain Engineering and Optimized Dielectric Properties of Antiferroelectric CaTiSiO5 Ceramics

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.