Effects of Mg2+ addition on structure and electrical properties of gadolinium doped ceria electrolyte ceramics

Abstract

Series of Gd 3+ and Mg 2+ co-doped ceria (Ce 0.8 Gd 0.2-x Mg x O 1.9-δ ) powders were prepared by a sol-gel method and electrolyte ceramics were obtained by sintering at 1300°C. Thermogravimetric and differential scanning calorimetry, X-ray diffraction, scanning electron microscope and electrochemical impedance spectroscopy were used for structural, morphology and electrical characterization of the prepared samples. Well crystalline cubic fluorite structured composite was confirmed after calcination at 700°C and the electrolyte ceramics sintered at 1300°C for 4 h was quite dense with uniform microstructure. The electrochemical analysis results displayed that the highest conductivity has the Ce 0.8 Gd 0.14 Mg 0.06 O 1.87 compound, i.e. 0.0203 S/cm at 800°C. Therefore, it was concluded that co-doping with Gd 3+ and Mg 2+ could enhance the electrical properties of the CeO 2 based solid electrolytes.

Development of a new system of solid ionic conductors based on multi-doped ceria for application in IT-SOFCs

“…4. In comparison to previously reported results [23][24][25]35], on average, our samples showed the highest conductivity. Their original Nyquist plots for various temperatures were selected to illustrate the impedance behaviour of the investigated group of doped ceria samples as a whole [23][24][25]35].…”

“…As commonly known, the application complex electrochemical impedance spectroscopy (EIS) is well developed technique for characterization of the electrical properties of solid electrolytes based on the interfacial reaction at the electrode surface [19,21,[23][24][25][30][31][32][33][34][35]. Besides the total conductivity values, it provides useful information related to the contribution of grains' interior, grain boundaries, and electrode-electrolyte interface to the overall ionic conductivity [23][24][25].…”

“…As convenient starting ultrafine nanopowder intended for the production of ceramic electrolytes in IT-SOFCs, CeO 2 doped with different trivalent rare earth such as Nd, Sm, Gd, Dy and Y provides increased ionic conductivity [14,17,21,24]. Namely, the formation of oxygen vacancies (V •• ) in the cerium lattice allows to achieve the high ionic conductivity at lower temperatures, due to the replacement of Ce 4+ ions with rare earth (III)-valent ions as dopants for the purpose of the compensation of the charge balance in the lattice [25,26].…”

Synthesis and characterization of CeLaMO2 (M: Sm, Gd, Dy) compounds for solid ceramic electrolytes

“…This reduction is not desirable as it causes electronic conductivity. Transition metals and/or lanthanum group elements with low oxidation state are added to prevent reduction and increase ion conductivity [8][9][10][11][12]. This doping is obtained by sol-gel, hydrothermal, solid state, ultrasound and co-precipitation methods [13,14].…”

“…Samarium (Sm), magnesium (Mg), calcium (Ca), barium (Ba), dysprosium (Dy), copper (Cu), erbium (Er), gadolinium (Gd), praseodymium (Pr) etc. have been doped into CeO 2 and their structures have been investigated [12,[15][16][17][18][19]. However, studies on codoping with two metal ions are limited in the literature.…”