Resumo de eventos cient??ficos
Phase stability and ionic conductivity of spark plasma sintered scandia-zirconia containing additives
Autor
GROSSO, ROBSON L.
TERTULIANO, ANA J.
MACHADO, IZABEL F.
MUCCILLO, ELIANA N. dos S.
BRAZILIAN MRS MEETING, 15th
Resumen
Scandia-stabilized zirconia exhibits the highest ionic conductivity in zirconiabased
solid electrolytes [1] and therefore is a candidate material for application in
solid oxide fuel cell operating at intermediate temperatures (600???800 ??C).
However, the crystal structure of this system is complex [1] and several attempts
have been made to stabilize the cubic (c) phase at room temperature. Recently,
addition of minor amounts of Al2O3, CeO2, Ga2O3, HfO2 was investigated for that
purpose [2,3]. In this work, the effects of 1 mol% additives (Dy2O3 and Nb2O5) on
zirconia- 10 mol% scandia (10ScSZ) were investigated aiming to stabilize the
cubic structure at room temperature and to suppress the characteristic cubic-torhombohedral
?? phase transformation. Compositions were prepared by the
coprecipitation method. Consolidation of the solid electrolyte was accomplished
by spark plasma sintering in the 1000???1400 ??C range for 1 and 5 min at 65 MPa.
The relative density for sintered samples was higher than 95% for temperatures
of 1200 ??C and higher. X-ray diffraction results show that full stabilization of the
cubic phase was attained after sintering for both prepared compositions.
Arrhenius plot of total ionic conductivity shows suppression of the reversible
phase transformation. Activation energy for oxide ion conduction is approximately
0.80 eV in the high temperature range (>600 ??C).