Ultrahigh dielectric permittivity in oxide ceramics by hydrogenation

Abstract

Boosting dielectric permittivity representing electrical polarizability of dielectric materials has been considered a keystone for achieving scientific breakthroughs as well as technological advances in various multifunctional devices. Here, we demonstrate sizable enhancements of low-frequency dielectric responses in oxygen-deficient oxide ceramics through specific treatments under humid environments. Ultrahigh dielectric permittivity (~5.2 × 10 6 at 1 Hz) is achieved by hydrogenation, when Ni-substituted BaTiO 3 ceramics are exposed to high humidity. Intriguingly, thermal annealing can restore the dielectric on-state (exhibiting huge polarizability in the treated ceramics) to the initial dielectric off-state (displaying low polarizability of ~10 3 in the pristine ceramics after sintering). 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. Conceptually, our findings are of practical interest for applications to highly efficient dielectric-based humidity sensors.

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“…11,12 Furthermore, ceramics with high insulation will be suitable for the dielectric layer in capacitor structures. 13,14 Besides, ceramic materials are no longer sensitive to defect cracking when they are scaled down below a critical value on the nanoscale. Because they may require more energy to crack and the growth of defects is inhibited by the possibility of amorphous phase transitions, grain boundary slip and dislocations during bending, ceramic nanostructures exhibit flexibility and elasticity.…”