Synthesis of Gadolinium Doped Ceria Solid Electrolyte by Solid State Reactions of CeO2/Gd2O3 Multilayer Thin Films

Abstract

The purpose of the present investigation is to study formation of Gd doped CeO2 solid electrolyte thin films by solid
state reactions of CeO2/Gd2O3 multilayer thin films deposited by reactive magnetron sputtering. Synthesis of cerium and
gadolinium oxide layers on Si and glass substrates was made by sputtering metallic Ce and Gd targets in Ar + O2
atmosphere. Single layer thickness was kept at 42 nm for CeO2 and 5 nm for Gd2O3. Mixing of the layers and formation
of Gd0.1Ce0.80O1.90 (GDC10) during annealing of coatings in 450 °C – 650 °C temperatures took place. X-ray diffraction
(XRD) studies using monochromatic CuKα radiation showed XRD (111) and (220) peaks shifting and asymmetry
changes after sample annealing. The annealing related crystallite size growth was confirmed using Scherrer equation and
Williamson-Hall plot. The investigation of morphology of the layers with a scanning electron microscope (SEM)
showed no multilayer structure in the films. Optical characterization of thin films on glass substrate was made by
UV-VIS spectrophotometer. Energy band gaps of undoped and Gd doped CeO2 films were determined using Tauc’s
relationship and were found to be 3.08 eV and 3.13 eV respectively.