Effects of Nd3+-substitution for Bi-site on the leakage current, ferroelectric and dielectric properties of Na0.5Bi0.5TiO3 thin films

Perovskite Na-0.5(Bi(1-x)Ndx)(0.5)TiO3(x = 0, 0.01, 0.03, 0.05; xNd: NBT) ferroelectric films were synthesized on indium tin oxide (ITO)/glass substrates via chemical solution deposition. Structural characterization shows the similar phase-pure perovskite structures in all the films and gradually decreased grain sizes with Nd3+ doping amount increasing. For all the films, the leakage behaviors are dominant by the Ohmic conduction in low electric field region and interface-limited Fowler-Nordheim tunneling mechanism in high electric field region. Additionally, the space-charge-limited conduction is involved in 0.03Nd: NBT sample. Compared with the sample of x = 0, the resistivity can be improved through Nd3+-substitution in NBT. Enhanced ferroelectricity can be obtained from the dynamic polarization -electric field test, and the reversible domains switching in film can be confirmed by static dielectric constant -electric field measurement. Especially, the 0.03Nd: NBT possesses optimal electrical performances with a large remanent polarization (P-r = 26.7 mu C/cm(2)) and a high dielectric tunability (19.6% at 100 kHz).