| Abstract Scope |
Broadband dielectric spectroscopy covering frequencies from the low MHz to the THz region has enabled the quantitative deconvolution of all polarizations in dielectric oxides. This analysis demonstrated that the high dielectric constant of BaTiO3 (BT) originates from ionic polarization associated with ferroelectric soft modes, which contribute dielectric constants in the range of several hundred, as well as from dipole contribution arising from domain structures that can exceed eᵣ = 1,000. Microwave dielectric measurements under a DC electric field, applied to BT-based compounds doped with various elements, further elucidated the polarization behavior related to domain configurations responsible for permittivity decrease. These insights are highly valuable for the rational design of high-power-driven multilayer ceramic capacitors (MLCCs).
In parallel, dielectric nanoparticles were integrated into the active materials of lithium-ion batteries, where BT incorporation drastically enhanced the high-rate capability. A series of investigations revealed that dielectric additives can significantly increase the adsorption activity of solvated lithium ions. This demonstrated the insulators—typically regarded as detrimental to carrier transport—can instead be harnessed to enhance secondary battery characteristics. |