중저온형 고체산화물 연료전지를 위한 La1-xSrxGa1-yMgyO3-δ 전해질의 제조 및 특성에 관한 연구 : A Study on Synthesis and Characterization of La1-xSrxGa1-yMgyO3-δ Electrolyte for IT-SOFC
- 발행기관 고려대학교
- 발행년도 2005
- 학위수여년월 2005. 8
- 학위명 석사
- 학과 대학원 재료공학과 금속재료전공
- 식별자(기타) DL:000015976202
- 서지제어번호 000045217047
초록/요약
Abstract La1-XSrXGa1-YMgYO3-δ powders of four different compositions (X, Y=0.1 or 0.2) (such a symbolic system as LSGM9191 for X=0.1 and Y=0.1 or LSGM9182 for X=0.1 and Y=0.2 is used hereafter) were synthesized as the electrolyte material of the intermediate temperature solid oxide fuel cell (IT-SOFC) using glycine nitrate process (GNP). They were then calcined at 900℃ for 2 hours, compacted into a disc (or a rod), and sintered at 1400℃ for 4 hours for structural, electrical and thermomechanical characterizations. The reactivity of an LSGM with a cathode material such as LSM (La0.85Sr 0.15MnO3) or LSCF (La0.6Sr0.4Co0.2Fe0.8O3) was analyzed by holding the LSGM/cathode powder mixture at 1000℃ for 100 hours and then searching for possible reaction product phases in its XRD pattern. A first glance at the XRD patterns of the four LSGMs made us think that a single perovskite phase was formed for 9182, 9191 and 8282 compositions but a careful look afterwards revealed that there were very tiny traces of second phases in the latter two. Nevertheless, the electrical conductivity of 8282 (0.084S/cm at 750℃) turned out to be higher than that of 9182 (0.062S/cm at 750℃). This is the highest among the conductivity values of the four LSGMs and about two and half times as high as the conductivity of YSZ (0.039S/cm). The linear thermal expansion coefficient was measured to be 11.70x10-6/K for 9182 and 12.14x10-6/K for 8282 which are similar to that of LSM (11.68x10-6/K) and lower than that of LSCF (19.18x10-6/K).
more초록/요약
Abstract La1-XSrXGa1-YMgYO3-δ powders of four different compositions (X, Y=0.1 or 0.2) (such a symbolic system as LSGM9191 for X=0.1 and Y=0.1 or LSGM9182 for X=0.1 and Y=0.2 is used hereafter) were synthesized as the electrolyte material of the intermediate temperature solid oxide fuel cell (IT-SOFC) using glycine nitrate process (GNP). They were then calcined at 900℃ for 2 hours, compacted into a disc (or a rod), and sintered at 1400℃ for 4 hours for structural, electrical and thermomechanical characterizations. The reactivity of an LSGM with a cathode material such as LSM (La0.85Sr 0.15MnO3) or LSCF (La0.6Sr0.4Co0.2Fe0.8O3) was analyzed by holding the LSGM/cathode powder mixture at 1000℃ for 100 hours and then searching for possible reaction product phases in its XRD pattern. A first glance at the XRD patterns of the four LSGMs made us think that a single perovskite phase was formed for 9182, 9191 and 8282 compositions but a careful look afterwards revealed that there were very tiny traces of second phases in the latter two. Nevertheless, the electrical conductivity of 8282 (0.084S/cm at 750℃) turned out to be higher than that of 9182 (0.062S/cm at 750℃). This is the highest among the conductivity values of the four LSGMs and about two and half times as high as the conductivity of YSZ (0.039S/cm). The linear thermal expansion coefficient was measured to be 11.70x10-6/K for 9182 and 12.14x10-6/K for 8282 which are similar to that of LSM (11.68x10-6/K) and lower than that of LSCF (19.18x10-6/K).
more목차
Fig. 10. Equilibrium phase diagram for La1-xSrxGa1-yMgyO3-δ.
Fig. 11. SEM images for LSGMs of (a) 9191, (b) 9182, (c) 8291, and (d)8282 compositions sintered at 1400℃ for 4 hours.
Fig 12. Impedance spectrum of LSGM9182 electrolyte prepared by GNPand sintered at 1400℃. The spectrum was measured at (a) 800℃and (b) 550℃.
Fig. 13. Arrhenius plot for ionic conductivity of La1-xSrxGa1-yMgyO3-δspecimens sintered at 1400℃ for 4 hours.
Fig. 14. Thermal expansion behaviors for (a) LSGM9182, (b) LSGM8282and (c) 8YSZ electrolytes compared with those of (d) LSCF and(e) LSM15 cathodes.
Fig. 15. Comparison of XRD patterns before and after a reaction of(a) LSGM8282/LSCF mixture or (b) LSGM8282/LSM15 mixtureat 1000℃ for 100 hours.
Fig. 16. Comparison of XRD patterns before and after a reaction of(a) LSGM9182/LSCF mixture or (b) LSGM9182/LSM15 mixtureat 1000℃ for 100 hours.
List of Tables
Table 1. Particle sizes for LSGMs of various compositions calcined at1000℃ for 2 hours.
Table 2. Average grain sizes and relative densities for LSGMs ofvarious compositions sintered at 1400℃ for 4 hours.
Table 3. Ioninc conductivity for LSGM 9182, 8282 compositions and8YSZ sintered at 1400℃ for 4 hours.
