Ultrahigh dielectric permittivity in oxide ceramics by hydrogenation
ORAL
Abstract
Boosting dielectric permittivity representing electrical polarizability of dielectric materials has been considered a keystone for achieving a new stage of scientific breakthroughs as well as technological advances in various multifunctional devices. In this work, we demonstrate the significant enhancement of low-frequency dielectric constant in oxygen-deficient oxide ceramics via the hydrogenation induced by water dissociation. In the as-sintered state, the initial dielectric constant in Ni-substituted BaTiO3 ceramics is very low (~103 at 1 Hz, the off-state). When ceramics are exposed to high humidity, a giant dielectric constant (~106 at 1 Hz, the on-state) is obtained, which is three orders of magnitude higher than that in the pristine state. It appears that the ultrahigh dielectric permittivity in the on-state is restored to the original value in the off-state via the thermal annealing. The conversion between these two dielectric states via the ambient-environment-mediated treatments and the successive application of external stimuli allows us to realize reversible control of dielectric relaxation characteristics in oxide ceramics. The achieved huge dielectric permittivity in the ambient-environment-treated Ni-substituted BaTiO3 ceramics would originate from spatial inhomogeneity of electrical polarizability induced by the hydrogenation. Conceptually, our work is of potential interest for realizing a new concept of ceramic-based dielectric sensors (e.g., hygrometers), which are able to detect water vapor in ambient air with high efficiency and sensitivity.
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Presenters
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Nguyen Xuan Duong
- University of Ulsan, Republic of Korea
- U. of Ulsan