1. Investigation of the microstructure in the Yttrium-Tantalate-Zirconia system
Thursday, August 27, 2015

2. Yttrium-Tantalate-Zirconia system

3. Thermal conductivities of the system
Very low thermal conductivities (< 2 Wm-1K-1)

4. Quasi-binary phase diagram
3 phases in the 30 to 60 mol % ZrO2 region?

5. Transition takes place at 1475 °C for pure YTaO4
Phases of YTaO4
Transition takes place at 1475 °C for pure YTaO4

6. Imaging techniques used
Transmission Electron Microscopy
Scanning Electron Microscopy

7. Transmission Electron Microscopy at the Center for Nanoscale Systems (CNS)
JEOL 2100 TEM

8. Inside a TEM

9. Requirements for TEM Sample has to be very thin (<100 nm)
Hence specific technique to prepare samples
Hand polishing and ion milling
Focused Ion beam

10. Sample Preparation Chosen method was hand polishing and ion milling
Started from discs and cut cross section
Polish down to about 100 m

11. Fischione Model 200 Dimpling Grinder

12. Gatan Model 691 Precision Ion Polishing System
Ion milling
Trickiest part in sample preparation
Sputtering of molybdenum on the sample
Gatan Model 691 Precision Ion Polishing System

13. Finding a recipe that works
Fischione Model 1010 Ion mill

14. New equipement
CNS bought Fischione Model 1050 TEM mill

15. Contacting an expert
Contact Rocco Cerchiara, TEM sample preparation expert from Fischione, to ask for a possible recipe for ion milling
Suggested using high angles and low energy to remove molybdenum being sputtered

16. Double tilt Beryllium sample holder
Ready for Imaging!!!
Double tilt Beryllium sample holder

17. TEM Image of 50 mol % ZrO2

18. HRTEM Image of 50 mol % ZrO2

19. Selected area electron diffraction of 50 mol % ZrO2

20. SEM Image of 50 mol % ZrO2

21. SEM Image of 50 mol % ZrO2 cross section
Probably bands seen on previous SEM image?

22. Concluding remarks
Finally find a good recipe for sample preparation but not enough time to complete observations!!!
Bands structure in 50 mol % ZrO2 possibly due to the fact that this composition is very close to the eutectoid composition

23. Any Questions?