Fig. 5. The reversible change of dielectric responses in Ni-substituted BaTiO₃ ceramics.

(A) The schematic of the experimental sequence to test recyclability of the dielectric on- and off-states. (B) The evolution of the frequency-dependent dielectric constant and loss of Ni-substituted BaTiO₃ ceramics under the repetitive cycles of a high-humidity treatment and thermal annealing. (C) The number of cycle dependence of dielectric constants at 1 Hz for the dielectric on- and off-states induced by the humidity treatment and the following thermal annealing, respectively. The red and blue circles represented the dielectric permittivity of ceramic samples after the thermal annealing (i.e., off-state) and after the treatment under a humid environment (i.e., on-state), respectively.