Development of powder diffraction analysis tools for a nanocrystalline specimen:

1
Development of powder diffraction analysis tools
for a nanocrystalline specimen

• An emphasis upon NiTi (Nitinol)

Erich Owens Albion College Stanford Linear
Accelerator Center August 16th, 2006
2
X-ray diffraction

• Braggs law

?
?
d
?
3
Powder Diffraction Basics
4
Features of the Diffraction Image

• Peak width
• Crystallization of material

• Peak intensity
• Texture

• Peak location
• Lattice spacing (d)

5
Overview
Signal Identification and Extraction
Data
Science
e.g.
6
Features of the Diffraction Image
7
Signal versus Background
8
Data Analysis
9
Data Analysis
10
Data Analysis
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Relevant data needed and how to get there

• Each row (some chi value) to have a single peak
  fitted (Gaussian/Doppler, Lorentzian, or Voigt a
  convolution of Gaussian and Lorentzian
  distribution).
• Interpretation and subtraction of background from
  relevant signal
• Stored data along each chi of fitted peaks
  width, amplitude, and location.

12
Fitting the Curves
13
Data Analysis
14
Residues
15
Developed Algorithm

• Minimizes user input in determining signal from
  background
• Extracts needed peak qualities

16
Developed Algorithm (in action)
17
Pretty pictures of fitted data
Before
After
18
Overview (again)
Refinement and Signal Extraction
Data
Science
e.g.
19
Results succesful data extraction allows some
science to be performed
20
Acknowledgements

• Matthew Strasberg, Cornell University
• Apurva Mehta and Samuel Webb, Stanford Linear
  Accelerator Center
• SULI Program Coordinators at SLAC
• Office of Science, Department of Energy