Miran, H.A., Jiang, Z-T, Altarawneh, M., Veder, J-P, Zhou, Z-F, Rahman, M.M., Jaf, Z.N. and Dlugogorski, B.Z.
الملخص الانجليزي
The influence of the reaction gas composition during the DC magnetron sputtering process on the structural,
chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed
that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. Xray
photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as
CeO2 and Ce2O3, at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas
the films are completely oxidized into CeO2 as the aforementioned ratio increases beyond 14%. Various optical
parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the
UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised
from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a
mixture of Ce2O3 and CeO2 in the films. Density functional theory (DFT+U) implemented in the Cambridge
Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO2 clusters at
ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO2 yields a band
gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption
coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength
range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the
theoretical and experimental findings.
حسين علي جان ميران | Hussein Ali Jan Miran | 2998