Formation and Investigation of Doped Cerium Oxide Thin Films Formed Using E-Beam Deposition Technique

Abstract

The investigation of new functional materials (ceramics) based on cerium (IV) oxides is a promising field of scientific research. A wide application in the industry received composite materials based on CeO₂–Gd₂O₃ and CeO₂–Sm₂O₃.

Thin ceramic films were formed on the basis of CeO₂ with 10 mol% Gd₂O₃ (GDC10), CeO₂ with 20 mol% Gd₂O₃ (GDC20), CeO₂ with 15 mol% Sm₂O₃ (SDC15), CeO₂ with 20 mol% Sm₂O₃ (SDC20) using e-beam technique in this work. The deposition rate and temperature of the substrate had influence on the formed doped cerium oxide GDC10, GDC20, SDC15, SDC20 thin films structure. Sm and Gd doped cerium oxide thin films were deposited on SiO₂, Alloy 600 (Fe-Ni-Cr), Si (111), Si (100) and Al₂O₃ substrates. Investigations of the formed thin films were carried out using a Scanning electron microscope (SEM), Electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy. It has been established that the cerium oxide based ceramic retains the crystalline structure, regardless of the concentration of the dopant and used substrate type. The most dominant crystallographic orientation of formed thin films was cubic (111). Raman spectroscopy measurements showed the peak (465 cm⁻¹) of pure ceria corresponding to F_2g vibrational mode. First-order peaks, inherent to cerium oxide, were shifted to a region of lower wavenumbers and depend on dopant concentration. The peaks for all formed thin films were similar to each other in form but the position, half width and their intensity varied depending on the dopant concentration. Raman peaks position at 550 cm⁻¹ and 600 cm⁻¹ could be explained as change of oxygen vacancy amount due to the cerium transition between oxidized and reduced forms.