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

Abstract

Bi 1 − x Ce x FeO 3 (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 4f7/2, Bi 4f5/2, Fe 2p3/2, Fe 2p1/2, and O 1s peaks for Bi0.8Ce0.2FeO3 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 Bi0.8Ce0.2FeO3 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 Bi0.8Ce0.2FeO3 film are improved due to the decreased oxygen vacancies by the stabilized oxygen octahedron. Current density values for the BFO and Bi0.8Ce0.2FeO3 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.

First-principles study of structural, electronic, and ferroelectric properties of rare-earth-doped BiFeO3

“…The enhancement of remnant polarization has been reported in several papers [22][23][24][25][26][27][28][29]. The remnant polarization of La-doped BiFeO 3 thin films was 90 lC cm -2 , compared to undoped one, which was 70 lC cm -2 [26].…”

“…The remnant polarization of La-doped BiFeO 3 thin films was 90 lC cm -2 , compared to undoped one, which was 70 lC cm -2 [26]. Polarization-electric field hysteresis loops measurement [22] revealed that the value of the remnant polarization BiFeO 3 and Bi 0.8 Ce 0.2 FeO 3 films increases in electric field. According to Quan et al [22], the values of this parameter for the BiFeO 3 and Bi 0.8 Ce 0.2 FeO 3 thin films under an applied electric field of 621 kV cm -1 were 1.57 and 3.12 lC cm -2 , respectively.…”

“…It has been shown that the Bi 3? ion substitution by rare earth elements leads to destruction of spin cycloid [13][14][15][16][17][18][19][20][21], reduction of oxygen vacancies in BiFeO 3 [22,23], and enhancement of remnant polarization [22][23][24][25][26][27][28][29].…”

Structural, Ferroelectric and Ferromagnetic Properties of Single-Phase Bi0.95Ba0.05FeO3 Thin Film Prepared by Pulsed Laser Deposition

“…The epitaxial BFO thin films exhibited large remanent polarization P r (50-150 μC cm −2 ) and large coercive field E c (100-250 kV cm −1 ) [1,11]. Substitutions of partial Bi 3+ at A-sites with Pr 4+ , Ce 3+ , Er 4+ , and Ba 2+ ions have been proved to be a good way to improve the magnetic properties of BFO films [12][13][14][15][16][17][18]. Among them, Ba 2+ ions are shown to be the best substitution for enhancing saturation magnetization.…”

Resistive switching properties of Ce and Mn co-doped BiFeO3 thin films for nonvolatile memory application

“…Appropriate Ce cations might be used to substitute for A site Bi 3+ in the BiFeO 3 matrix and Ce cations could stabilize oxygen octahedron that helps decrease Bi volatilization and improve the crystallization. 25,26 Moreover, doping at the Fe site with aliovalent atoms, such as Mn, is found to be advantageous in reducing leakage current and improving both electrical and magnetic properties of BiFeO 3 films. 27,28 The substitution of Mn ions is expected to affect the number of oxygen vacancies as well as the chemical states of Fe ions.…”