목차
1. 서언 1
2. BaZrO₃의 입자 내부 2
2.1. 프로톤 형성 2
2.2. 프로톤 이동 3
2.3. 프로톤 전도도 3
3. BaZrO₃의 입계 4
3.1. 프로톤 형성 4
3.2. 프로톤 이동 7
3.3. 프로톤 전도도 7
4. 표면 7
5. 결언 9
참고문헌 9
Fig. 1. Bulk proton conductivity of various oxide materials. 1
Fig. 2. Schematic view of PCFC (proton conducting fuel cell) consisting of anode, electrolyte, and cathode. The SEM image used in the electrolyte is BaZrO₃ which contains grain boundaries. 2
Fig. 3. The cubic perovskite structure of BaZrO₃. 3
Fig. 4. NH,B and NV,B in 10at.% Y-doped BaZrO₃ and BaCeO₃ as a function of temperature. The red and blue line swere calculated NH,B and NV,B under pH₂O of 0.025 atm, and the black lines were experimentally obtained ones.... 3
Fig. 5. Perspective views of two protons located in the bulk BaZrO₃ supercell and their migration pathways: rotation and transfer. 4
Fig. 6. Schematic of GB for the space charge layer model modified from Ref. The GB core is positively charged with △φ(0) and space charge layer with thickness of λ*. 4
Fig. 7. The atomic structure of the (210)[001](0,1/2) grain boundary. The dashed lines mark the region which is treated as the grain boundary core in the space-charge calculations. 4
Fig. 8. Stoichiometric and nonstoichiometric BaZrO3 (210)[001] tilt grain boundaries (GBs): (a) and (d) are the BaO and ZrO₂ GBs, respectively. Based on the BaO and ZrO₂ GBs, (b), (c), (e), and (f) were constructed by removing cations... 5
Fig. 9. Grain boundary energies (Ω) (a) as a function of △μBa at 1000 K and 0.2 atm of po₂, and as a function of log(po₂ /p0) at 1000 K under the conditions of (b) △μBa+△μO = △HBaO and (c) △μBa+△μO =△HBaZrO₃-△HzrO₂. 5
Fig. 10. Oxygen vacancy and proton segregation energies of the (210)[001](0,1/2) grain boundary. The dashed lines mark the region which is treated as the grain boundary core in the space-charge calculations.... 5
Fig. 11. Schematic diagram for △ϕ(0), where n (n = 0, 1, 2, ...) is the number of times that iterative procedure has been performed and A0 and An+1 are an assigned and calculated △ϕ(0), respectively.... 6
Fig. 12. (a) and (b) show the oxygen vacancy and proton concentration under wet conditions in the bulk and grain boundary core respectively while (c) shows the space-charge potential barrier height △ϕ(0) for wet and dry conditions.... 6
Fig. 13. Profiles of the electrostatic potential difference (△ϕ) and the concentrations (CD) of H and V as a function of z at (a) 600, (b) 900, and (c) 1200 K, respectively. The dark-yellow, light-yellow, and white areas represent the GB core (GBC),... 7
Fig. 14. (a) A schematic image shown along the [001] direction and (b) energy variation of the three plausible pathways for proton migration from the left grain through the GB to the right grain in the Y-doped BaZrO3₃. 7
Fig. 15. Proton migration from surface into bulk; (a) a proton migration pathway at the surface and (b) the corresponding energy variation as a function of z. 8
Fig. 16. Profiles of the electrostatic potential difference (△ϕ) and the concentrations (CD) of H and V as a function of z at (a) 600, (b) 900, and (c) 1200 K, respectively. The white, dark-yellow, light-yellow, and grey areas represent the vacuum,... 8
Fig. 17. Logarithmic scale of ρH as a function of z. The solid and one dot chain lines indicate the ρH of surface, and ρH of the bulk, respectively. 8
Fig. 18. Logarithmic scale of σT as a function of inverse temperature (1/T). The one dot chain and two dot chain lines represent bulk and grain boundary conductivities, respectively.... 9
Fig. 19. Possible reaction at the cathode electrode using a H+/e- mixed conductor cathode material. 9