1. It's cute (可爱)………
But does it DO anything??

2. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
Every material has a unique x-ray powder pattern
Every PHASE has a unique powder pattern
This image, taken under a microscope, shows that a 'duplex stainless steel' has two phases - austenite (AUS) & ferrite (FE)
AUS FE
This is the X-ray diffraction pattern

3. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
The X-ray diffraction
pattern tells us this
AUS FE
How?

4. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
We use the Powder Diffraction File database (the PDF) and a search system
History
1938 Hanawalt paper on first database and search method
1941 ASTM committee publishes database on cards
1969 JCPDS incorporated; publishes the JCPDF

5. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
We use the Powder Diffraction File database (the PDF) and a search system
History
1938 Hanawalt paper on first database and search method
1941 ASTM committee publishes database on cards
1969 JCPDS incorporated; publishes the JCPDF
1977 JCPDS became the International Centre for Diffraction Data (ICDD) - currently publishing various databases, including the new PDF-4, with diffraction and structure data for >240,000 phases

15. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
Make d, I list:
Do search/match

16. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
Example of page of search manual for
Hanawalt manual search/match

17. Powder diffraction - applications
Qualitative analysis - what IS this stuff?!!
Do search/match
Make d, I list:
no match
no match
1 2 x - no match
no match
no match
1 3 x - no match
no match
MATCH!

19. Powder diffraction - applications
1. Qualitative analysis
Quantitative analysis
Crystal structure determination
Crystallite size
Microstrain
Residual macrostresses ?

20. stress = modulus x strain
Powder diffraction - applications
1. Qualitative analysis
Quantitative analysis
Crystal structure determination
Crystallite size
Microstrain
Residual macrostresses
stress = modulus x strain
 = E 
(Hooke's law)

21. Powder diffraction - applications
Residual stress
Reflections shift position (d-values change under stress)

22. Powder diffraction - applications
Residual stresses

23. Residual stress Suppose isotropic solid loaded in uniaxial tension
Can measure change in interplanar spacing for planes reflecting as above
d = (d - do)/ do - this is the strain 
 = (1/E) ( - ( + )) -  is Poisson's ratio
 = - (1/E)  - so, can get stress 

24.  =  (1 + )/E sin2  /E)( + 
Residual stress
Biaxial & triaxial stress states more complicated
Stress state resolved differently along different directions in sample, so peak shifts change w/ direction     
 =  (1 + )/E sin2  /E)( +  

25. Residual stress Measurement procedure - classical technique - sin2 
Diffractometer must have two more rotations - and       

26. Residual stress Measurement procedure - classical technique - sin2 





27.  =  (1 + )/E sin2  /E)( + 
Residual stress
Measurement procedure - classical technique - sin2 
slope
 =  (1 + )/E sin2  /E)( + 

sin2 
Need E,  -
measure or
calculate

28. Powder diffraction - applications
1. Qualitative analysis
Quantitative analysis
Crystal structure determination
Crystallite size
Microstrain
Residual macrostresses
Thin films

29. Powder diffraction - applications
Thin films

30. Powder diffraction - applications
Thin films

31. Powder diffraction - applications
Thin films

32. Powder diffraction - applications
Thin films

33. Powder diffraction - applications
Thin films
Can rotate
film and still
get reflection

34. Powder diffraction - applications
Thin films

35. Powder diffraction - applications
1. Qualitative analysis
Quantitative analysis
Crystal structure determination
Crystallite size
Microstrain
Residual macrostresses
Thin films
Crystallinity
9. Studies of phase diagrams
A. Phase boundaries
B. Solid solutions
C. Phase transitions
10. Studies of chemical reactions and identification of reaction products.
11. Determination of grain sizes.
12. Preferred orientation in polycrystalline bodies.
13. Many more