Very short summary of the paper "Solving the Structure of Li Ion Battery Materials with Precession Electron Diffraction: Application to Li2CoPO4F", published in Chem. Mater.

2. The problem:
Structure of Li2CoPO4F cannot be solved or
refined from bulk diffraction.
The solution:
Precession electron diffraction càn get the
job done.
This presentation describes the procedure
in the shortest way possible.

3. For a more detailed treatment:
“Solving the Structure of Li Ion Battery Materials with
Precession Electron Diffraction: Application to Li 2CoPO4F”
in Chemistry of Materials
by Joke Hadermann, Artem M. Abakumov, Stuart Turner,
Zainab Hafideddine, Nellie R. Khasanova, Evgeny V. Antipov
and Gustaaf Van Tendeloo
Published online July 11, 2011
http://pubs.acs.org/doi/abs/10.1021/cm201257b

4. First, electron
diffraction patterns are
taken, using the
precession attachment.
Non main zones have
more reliable peak
intensities than main
zones.

5. All patterns can be indexed using the cell
parameters and space groups known from XRD:
a= 10.452(2) Å, b= 6.3911(8) Å, c=10.874(2) Å
Pnma

6. The intensities of the observed peaks are extracted
(ELD software).
Treated: symmetry equivalent reflections merged,
geometric corrections applied
Merged into one list (Triple software)
We now have intensities of
237 symmetry unique reflections

7. a= 10.452(2) Å,
Intensities of 237
b= 6.3911(8) Å, & symmetry unique
c=10.874(2) Å
reflections
Pnma
INTO
Direct Methods

8. Result: R=31%
CO and P positions similar to Li2FePO4F
but
Li, O, F mixed over remaining positions
Assign
F: tetrahedra around P
O: complete the octahedra around Co
Remaining positions (purple) Li or ghosts?
Difference Fourier maps including Co,P,O,F

9. The difference Fourier maps
clearly show the real peaks
The Li-atoms are now also located

10. Straight from direct methods:
too many Li(?) peaks
Difference Fourier allows
to eliminate the grey ones
Structure is solved !

11. Can be refined...

12. Separate list of intensities per zone were
put into Jana using separate scale factors
for each list on input
&
Use PO4 rigid units:
18 variables reduced to 6
R=24% (reasonable for precession
electron diffraction data)

14. Conclusion
Li2CoPO4F was successfully solved and
refined from precession electron
diffraction
PED can be successfully applied
for the crystallographic characterization
of Li-based battery materials