3D EBSD of SOEC materials at Risoe DTU

Transcription

1 3D EBSD of SOEC materials at Risoe DTU Nath Saowadee Risø-DTU National Laboratory for Sustainable Energy Fuel cell and solid state chemistry Division

2 topics Electron Backscattered Diffraction (EBSD) 3D EBSD 3D EBSD of STN Problems of performing 3D EBSD of SOC materials conclusion 2 Risø DTU, Technical University of Denmark

3 Electron Backscattered Diffraction (EBSD) 3 Risø DTU, Technical University of Denmark

4 EBSP processing (indexing) Selected phases Phase 1 Phase 2 Phase 3 Bands generation Bands fitting Bands detection EBSP phases MAD orientation Phase (ϕ 1, ϕ 2, ϕ 3 ) Phase (ϕ 1, ϕ 2, ϕ 3 ) Phase 3 none none MAD : mean angular deviation 4 Risø DTU, Technical University of Denmark

5 Measurable quantities from an EBSP Crystal orientation Phase consistency (MAD) Pattern quality (Band contrast) phases MAD orientation Phase (ϕ 1, ϕ 2, ϕ 3 ) Phase (ϕ 1, ϕ 2, ϕ 3 ) Phase 3 none none 5 Risø DTU, Technical University of Denmark

6 Crytal structure infomation from EBSD Crystal orientation angles Orienation mapping Texture, crystal prefered orientation Phase consistency (MAD) Phase identification Phase mapping Pattern quality (Band contrast) Grain size/shape and boundaries 6 Risø DTU, Technical University of Denmark

7 Orientation mapping Euler angle (ϕ 1, ϕ 2, ϕ 3 ) blue red green Euler color space 7 Risø DTU, Technical University of Denmark

8 Phase mapping Ni-YSZ phase MAD Display color Ni Y 2 O EDS Base on composition EBSD Base on crystal structure 8 Risø DTU, Technical University of Denmark

9 Grain size shape and boundaries High contrast SE2 image Band contrast image Nb-doped strontium titanate High contrast Low contrast 9 Risø DTU, Technical University of Denmark

10 Three dimensional Electron Backsattered Diffraction (3D EBSD) FIB milling position EBSD position Oxford Instruments HKL 3D EBSD system 10 Risø DTU, Technical University of Denmark

11 3D EBSD of an SOFC (test case) Ni (cubic, Space group =225) Y 2 O 3 (cubic, Space group =206) Ni-YSZ YSZ electrolyte Cathode Orientation mapping (Euler color) Dimension:28.2x25.8x10.2 μm 3 Resolution:200x200x200 nm 3 11 Risø DTU, Technical University of Denmark

12 Phase distribution Band contrast mapping Ni (cubic, a = 3.57 A) Y 2 O 3 (cubic, a = A) 28.2x25.8x10.2 μm 3 Phase mapping 12 Risø DTU, Technical University of Denmark

13 Grain size and shape Volume Surface area Neighbours Orientation mapping (Euler color) Dimension:28.2x25.8x10.2 μm 3 Resolution:200x200x200 nm 3 13 Risø DTU, Technical University of Denmark

14 Phase investigation in 2D EBSD Sr 0.94 Ti 0.1 Nb 0.1 O 3 (1440 C, in air) Phase mapping ScYSZ electrolyte CGO/Ni on STN electrode Another phase Too much fitting bands (15 bands) Nb-doped Sr-Titanate STN base electrode SOEC Phase list SrTiO 2.6 (Tetragonal, a=3.92 A, c=3.89 A, a:c = ) SrTiO 3 (cubic, a=3.90 A) SrNbO 3 (cubic, a=4.12 A) Black = cannot be identified (Zero solutions) 14 Risø DTU, Technical University of Denmark

15 3D EBSD of STN SrTiO 2.6 (Tetragonal) Ni-YSZ, YSZ electrolyte Orientation mapping (Euler color) Dimension:26.6x25.8x4.6 μm 3 Resolution:200x200x200 nm 3 15 Risø DTU, Technical University of Denmark

16 Problems of performing 3D EBSD of SOCs material 1. Charging 2. FIB damage 3. Pseudosymmetry 16 Risø DTU, Technical University of Denmark

17 1. Charging Coated sample Ni-YSZ YSZ electrolyte Cathode During FIB milling 17 Risø DTU, Technical University of Denmark

18 2. FIB damage on sample surface 120,0 115,0 Band contrast 110, ,0 100,0 95,0 90, FIB current (pa) 18 Risø DTU, Technical University of Denmark

19 3. Pseudosymmetry of SrTiO 2.6 Tetragonal SrTiO 2.6 a:c =3.92:3.89 = (100) (100) (100) Sr Ti O O 19 Risø DTU, Technical University of Denmark

20 Future work ScYSZ electrolyte CGO/Ni on STN electrode Nb-doped Sr-Titanate STN base electrode SOEC 20 Risø DTU, Technical University of Denmark

21 Conclusion EBSD technique can be used for obtaining crystallographic orientation, performing phase identification, investigating grain size/shape and boundary. There three important problems of performing 3D EBSD of SOC materials Charging problem, can be solved by coating sample. FIB damage, need investigate FIB damage before performing 3D EBSD Pseudosymmetry of low symmetry crystal structure material. 21 Risø DTU, Technical University of Denmark

22 Thank you for your attention