高効率ジルコニア固体電解質型燃料電池の開発(I) : 高性能スカンジア安定化ジルコニア固体電解質

Abstract

Sc_2O_3 (scandia)-doped cubic zirconia electrolyte with high electrical conductivity sintered at low temperature and scandia-doped tetragonal zirconia electrolyte having improved mechanical strength were developed. 1 mol% Bi_2O_3-10 mol% Sc_2O_3-doped zirconia with cubic structure sintered at 1200°C had sufficient conductivity of 0.33 S/cm at 1000°C and did not show cubicrhombohedral phase transformation. Dense zirconia ceramics fabricated by sintering at 1300℃ for 1 h in air followed by hot isostatic pressing (HIP) at 196 MPa at 1450℃ for 1.5 h in an Ar gas atmosphere, which consisted of submicrometer-sized grains of tetragonal phases and were stabilized with 5 and 6 mol% Sc_2O_3, exhibited high strength (1330 MPa and 1140 MPa, respectively) and good conductivity (0.15 S/cm and 0.18 S/cm at 1000℃, respectively).