Abnormal dielectric behavior induced by defect dipoles in aged Na0.5Bi0.5(Ti,Zr)O3 thin film

Ferroelectric aging behavior was investigated in Na0.5Bi0.5(Ti0.99Zr0.01)O3 thin film on FTO/glass substrate by the dielectric constant (dissipation factor)-electric field (εr-E and tan δ-E) curves. The aged sample can be gained by keeping the fresh film for two months at room temperature. Compared with the typical single butterfly εr (tan δ)-E of the fresh sample, an abnormal loop has been exhibited in the aged one. Furthermore, with the increase of the measuring electric field or decrease of applied frequency, the aging phenomenon becomes weak and even disappeared. These present results are analyzed based on defect chemistry by the symmetry-conforming principle of defect dipoles.