Conductivity and impedance spectroscopic studies of self-sustained high-temperature synthesized nano-Ce1-xGdxO2-δ solid solutions

• Published in: Ionics 2021-03, Vol.27 (3), p.1205-1220
• Main Authors: Reddy, M. V. Hemantha, Reddy, T. Sreenivasulu, Krishna, R. Hari, Chandraprabha, M. N., Sasikumar, M., Jegatheesan, P., Nagabhushana, B. M.
• Format: Article
• Language: English
• Subjects: Cerium oxides; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Conductivity; Electrochemistry; Energy Storage; Gadolinium; High temperature; Impedance; Optical and Electronic Materials; Original Paper; Renewable and Green Energy; Solid solutions; Synthesis; Temperature dependence
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-020-03844-7

Despite extensive research on CeO 2 in diverse fields, studies on dielectric, conductivity behaviours due to intentional impurity-induced structural and microstructural changes are not well established. We show that structural changes arising due to Gd 3+ in nano-CeO 2 and the temperature affect the dielectric and conductivity characteristics. Highly crystalline nano-CeO 2 and Ce 1-x Gd x O 2-δ (GDC) ( x  = 0.02–0.1) are synthesized by self-sustained high-temperature synthesis. The dependence of conductivity on dopant concentration is examined over a wide-frequency (20 Hz to 10 MHz) and temperature (200–800 °C) range using a precision impedance analyzer. The conductivity reaches maximum at x  = 0.06 for Ce 1-x Gd x O 2-δ at 600 °C beyond which conductivity decreases. There is dependence of conductivity at lower frequencies, increases with increasing frequency, and gets saturated at higher frequencies. The optimum concentration ( x  = 0.06) found is the lowest for the Ce 1-x Gd x O 2-δ system reported. The observed behaviour is discussed in terms of interaction between oxygen vacancies and defect associates.