Effect of Intrinsic and Extrinsic Oxygen Vacancies on the Conductivity of Gd-Doped CeO₂ Synthesized by a Sonochemical Route

Abstract

The present study reports the effect of a dopant (gadolinium, Gd) on the grain size, generation of oxygen vacancies, and conductivity in ceria. Undoped and doped ceria (Ce 1−x Gd x O 2−δ , x = 0, 0.10, 0.20, and 0.30) are synthesized by the ultrasound-assisted sol−gel combustion method, followed by sintering at 1450 °C for 4 h. X-ray diffraction studies confirm the formation of the cubic fluorite phase. The lattice parameter variation confirms that the solid solubility limit of present samples lies between x = 0.20 and x = 0.30. The crystallite size of the powders ranges between 5 and 30 nm. The morphology of sintered materials is studied using scanning electron microscopy. Raman spectroscopy is used to investigate the presence of different structural defects and oxygen vacancies in undoped and Gd-doped ceria (CeO 2 ) samples. It also helped to detect the secondary phase formed in the GDC-30 sample. Ce 0.9 Gd 0.1 O 2−δ with a uniform, dense morphology and the presence of oxygen vacancies has the highest electrical conductivity (1.67 × 10 −2 S cm −1 at 600 °C). It could be a suitable material for electrolytes in solid-oxide fuel cells.

Innovative Applications of Cerium Oxide-Based Materials in Civil Engineering, Automation, and Energy Sectors

“…Additionally, their conductivity and other properties can be easily modified by varying their structure and porosity [250,251]. Further improvement can be achieved when CeO 2 is doped with other elements, such as La [252], Gd [253][254][255], In [256], Y, Zr [257], Fe, Cu [258,259], etc.…”

Structural, Optical, Magnetic and Electrochemical Properties of CeXO2 (X: Fe, and Mn) Nanoparticles

“…The oxygen vacancies can modify the conductivity via charge delocalization. Owing to its unique modifiable electronic properties, CeO 2 takes part in the electrochemical reactions in such a way as to facilitate the charge transport in electronic components [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. In addition, CeO 2 can display synergistic effects when combined with other materials.…”