Microstructure and ferroelectric properties of compositionally graded Nd-doped Bi_4Ti_3O_(12) thin films prepared by sol-gel method

摘要

The compositionally graded Bi_(4_x)Nd_xTi_3O_(12) (BNT) thin films were prepared on Pt/Ti/SiO_2/Si substrates by sol-gel method. Their microstructure, ferroelectric and dielectric properties were investigated. The single-phase upgraded and downgraded BNT films were obtained with (117) preferred orientation. Compared to the homogeneous BNT films prepared by the same conditions, the remanent polarization (P_r) and permittivity (ε_r) of compositionally graded BNT films were significantly enhanced. The upgraded BNT film showed larger 2P_r (34.9 μC/cm~2) and ε_r (509), and those of downgraded BNT film were 29.4 μC/cm~2 and 505. Bi element in the downgraded BNT film accumulated near the interface of film/Pt bottom electrode, which deteriorated the compositional gradient and resulted in decreasing 2P_r and ε_r compared to the upgraded BNT film.