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Phase Stability of 10mol%Sc2O3-1mol%CeO2-ZrO2 Ceramics

Published online by Cambridge University Press:  01 February 2011

Sergey Yarmolenko
Affiliation:
[email protected], North Carolina A&T State University, Center for Advanced Materials and Smart Structures, 1601 E. Market St., 242 IRC, Greensboro, NC, 27411, United States
Svitlana Fialkova
Affiliation:
[email protected], North Carolina A&T State University, Mechanical Engineering, 1601 E. Market St., 242 IRC, Greensboro, NC, 27411, United States
Devdas M. Pai
Affiliation:
[email protected], North Carolina A&T State University, Mechanical Engineering, 1601 E. Market St., 242 IRC, Greensboro, NC, 27411, United States
Jag Sankar
Affiliation:
[email protected], North Carolina A&T State University, Mechanical Engineering, 1601 E. Market St., 242 IRC, Greensboro, NC, 27411, United States
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Abstract

Scandia-doped zirconia is a very promising material for solid oxide fuel cells due to its high oxygen conductivity in the 700-850°C temperature range. 10 mol% Sc2O3 - 1 mol% CeO2 - ZrO2 ceramics were sintered at temperatures 1100-1600°C using different heating rates and dwell times. Ceramics sintered at temperatures higher 1300°C were found to exist in cubic phase at room temperature and exhibit slow phase transformation from cubic (c) to rhombohedral (beta) phase between 330 and 400°C. Analysis of c-β phase transition efficiency in the ceramics shows a strong correlation between the transition rate and sintering temperature. Kinetics of phase transitions were studied by high temperature X-ray diffractometry (HTXRD) and differential scanning calorimetry methods. The reversible c-β phase transition was found to have very wide hysteresis (45-70°C), which depends on sintering temperature and density. Coefficients of thermal expansion of c- and β-phases were calculated from temperature dependence of lattice parameters obtained by HTXRD in the temperature range of 25-800°C. Microstructural changes on the surface of the cubic phase due to c-β phase transition studied by SEM and AFM.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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