Microstructure, electrical and magnetic properties of Ce-doped BiFeO3 thin films.

Bi_1-xCe_xFeO₃ (x=0, 0.05, 0.1, 0.15, and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si₃N₄/Si and fluorine-doped SnO₂ glass substrates by sol-gel technique, respectively. The effect of Ce doping on the microstructure, electrical and magnetic properties of BCFO films was studied. Compared to counterparts of BiFeO₃ (BFO) film, the fitted Bi 4f_7/2, Bi 4f_5/2, Fe 2p_3/2, Fe 2p_1/2, and O 1s peaks for Bi_0.8Ce_0.2FeO₃ film shift toward higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58, and 0.49 eV, respectively. Raman redshifts of 2–4 cm^-1 and shorter phonon lifetimes for the Bi_0.8Ce_0.2FeO₃ film might be related to anharmonic interactions among Bi–O, Ce–O, (Bi, Ce)–O, and Fe–O bonds in the distorted oxygen octahedron. Compared to the pure counterparts, the dielectric and ferroelectric properties of the Bi_0.8Ce_0.2FeO₃ film are improved due to the decreased oxygen vacancies by the stabilized oxygen octahedron. Current density values for the BFO and Bi_0.8Ce_0.2FeO₃ film capacitors are 9.89×10^-4 and 5.86×10^-5 A/cm² at 10 V, respectively. The current density–applied voltage characteristics indicate that the main conduction mechanism for the BCFO capacitors is the interface-controlled Schottky emission. Both the in-plane and out-of-plane magnetization–magnetic field hysteresis loops reveal that the saturation magnetization values of the BCFO films increase with increasing the Ce concentration. The enhanced magnetic properties for the BCFO films might be attributed to the presence of Fe²⁺ caused by oxygen vacancies, the suppressed spiral spin structure, and/or the increased canting angle induced by Ce doping. [ABSTRACT FROM AUTHOR]