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1 Journal of Achievements in Materials and Manufacturing Engineering

1 2009

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Effects of sintering on Y2O3-doped CeO2

Tavafoghi Jahromi M., Tan M. J.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 34, nr 2

130-136

Purpose: Having high electrical conductivity, Y2O3-doped CeO2 is a good candidate for various high temperature electrochemical devices, such as solid oxide fuel cells and oxygen gas sensor. However, its inferior mechanical properties compared to its competitors, e.g. ZrO2-based electrolytes, has restricted its usage. Design/methodology/approach: The present work evaluates the sintering behavior and mechanical properties of CeO2, and aims to enhance the mechanical properties and sinterability while restricting the grain growth by doping with Y2O3. Findings: The relative density, rather than the Y2O3 concentration, was the most important factor that affected the mechanical properties of CeO2. Increase of density resulted in higher hardness and elastic modulus, and lower the fracture toughness of CeO2. In the optimum condition, the KIC of 5.1 MPa.m1/2, nanohardness of 13.0 GPa, and elastic modulus of 371.5 GPa were obtained for the undoped CeO2 (density = 98.00%) sintered at 1700°C. Research limitations/implications: This study does not include sintering at higher temperatures. It is also worth investigating formation of oxygen vacancy or Ce2O3 material in the Y2O3-doped CeO2. Practical implications: It is noteworthy that in this study, the high temperature calcination of mixed powders is avoided in order to keep yitria as a second phase (not as a solute) in the ceria matrix. This enables yitria to be more effective to suppress the grain growth. Originality/value: The objectives are to improve the mechanical properties and to reveal the effects of various parameters, such as density, grain size, and yitria doping on the nano/micro indentation behavior of ceria material.