Ferroelectric behaviors and charge carriers in Nd-doped Bi 4Ti 3O 12 thin films

Abstract

Nd-doped Bi 4Ti 3O 12 thin films, (Bi 3.25Nd 0.85) 4Ti 3O 12, of layered perovskite structure were synthesized by if sputtering, followed by postannealing at 600-700°C. They show enhanced ferroelectricity with rising postannealing temperature in the range of 650-750°C. When annealed at 700°C, a remanent polarization 2P r of 25.2 μC/cm 2 and a coercive field E C of 87.2 kV/cm were measured at 9 V, together with an almost fatigue-free behavior up to 1.4 × 10 10 switching cycles. Their ferroelectric, dielectric, and ac conductivity properties over the temperature range from 25 to 300°C were studied over the frequency range of 0.1-1 MHz. Space-charge relaxation by oxygen vacancies was shown to play an important role in determining the dielectric and conductivity behaviors of Nd-doped Bi 4Ti 3O 12 thin films. © 2005 American Institute of Physics.