Surface chemical bonding states and ferroelectricity of Ce-doped BiFeO3 thin films prepared by sol–gel process
Bi1-xCexFeO3 (x = 0, 0.05, 0.1, 0.15 and 0.20)
(BCFO) thin films were deposited on Pt/TiN/Si3N4/Si
substrates by sol–gel technique. Crystal structures, surface
chemical compositions and bonding states of BCFO films were investigated by X-ray diffraction and X-ray photoelectron
spectroscopy (XPS), respectively. Compared to BiFeO3 (BFO) counterparts, the fitted XPS narrow-scan spectra of Bi 4f7/2, Bi 4f5/2, Fe 2p3/2, Fe 2p1/2 and O 1s peaks for Bi0.8Ce0.2FeO3 film shift towards higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58 and 0.49 eV, respectively. Dielectric constants and loss tangents of the BCFO (x = 0, 0.1 and 0.2) film capacitors are 159, 131, 116, 0.048, 0.041 and 0.035 at 1 MHz, respectively.Bi0.8Ce0.2FeO3 film has a higher remnant polarization (Pr = 2.04 lC/cm2) than that of the BFO (Pr = 1.08 lC/cm2) at 388 kV/cm. Leakage current density of the Bi0.8Ce0.2FeO3 capacitor is 1.47 9 10-4 A/cm2 at 388 kV/cm, which is about two orders of magnitude
lower than that of the BFO counterpart. Furthermore,
Ce cations are feasibly substituted for Bi3? in the
Bi0.8Ce0.2FeO3 matrix, possibly resulting in the enhanced
ferroelectric properties for the decreased grain sizes and the
reduced oxygen vacancies.
Zuci Quan, Hao Hu, Sheng Xu, Wei Liu, Guojia Fang, Meiya Li, Xingzhong Zhao
Acesse o CMDMC
Fotomicrografia típica de pisos cerâmicos.