This lecture was given at the IUCr (International Union of Crystallography) meeting in Madrid, 2011. Contents are focussed on the use of precession electron diffraction for functional materials, mainly lithium based battery materials, but also a perovskite was included, since a large part of the audience worked on that subject.
Workshop - Best of Both Worlds_ Combine KG and Vector search for enhanced R...
Electron crystallography for lithium based battery materials
1.
2. University of Antwerp, Belgium
Joke Hadermann
Artem M. Abakumov
Tyché Perkisas
Zainab Hafideddine
Stuart Turner
Gustaaf Van Tendeloo
Moscow State University, Russia
Nellie R. Khasanova
Evgeny V. Antipov
8. Example: Li2CoPO4F
The problem:
Structure cannot be solved from powder diffraction
There are no single crystals.
The solution:
Achieve single crystal diffraction of the powder
sample through precession electron diffraction.
10. 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
11. The intensities of the observed peaks are extracted
Geometric corrections applied
Merged into one list
We now have intensities of
237 symmetry unique reflections
12. Li2CoPO4F
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
13. Result: R=31%
Co and P ≈ Li2FePO4F
but
Li, O, F mixed up
F: tetrahedra around P
O: complete octahedra around Co
Remaining positions (purple): Li or ghosts?
Difference Fourier maps
14.
15. Straight from direct methods:
too many Li(?) peaks
Difference Fourier allows
to eliminate the grey ones
Structure is solved !
17. Separate list of intensities per zone into
Jana2006 using separate scale factors
&
Use PO4 rigid units:
18 variables reduced to 6
R=24% (reasonable for precession
electron diffraction data)
19. Li2CoPO4F was successfully solved and
refined from precession electron diffraction
PED can be successfully applied
for the crystallographic characterization
of Li-based battery materials
20.
21. A perovskite based example:
Pb13Mn9O25
Starting point:
a powder sample with nominal
composition Pb2Mn2O5
22. Electron diffraction reveals three phases...
Pnma; a= 5.7 Å, b=3.8 Å, c= 22 Å
1
P4/m;
2 a=b=14.2Å=
ap√13
c=3.9 Å=ap
3 In progress
33. Structure of Li2CoPO4F
solved using PED.
Presence of cubic phase
in layered phase LiCoO2
nanoparticles sample
detected by PED.
Structure of Pb13Mn9O25
solved using PED.
34. For a more detailed treatment:
“Solving the Structure of Li Ion Battery Materials with Precession
Electron Diffraction: Application to Li2CoPO4F”
Chem. Mater., 2011, 23 (15), pp 3540–3545
http://pubs.acs.org/doi/abs/10.1021/cm201257b
“Direct space structure solution from precession electron diffraction data:
Resolving heavy and light scatterers in Pb13Mn9O25 ”
Ultramicroscopy, 2010, 110, pp 881-890
Ultramicroscopy 110 (2010) 881–890
“New perovskite based manganite Pb2Mn2O5”
Journal of Solid State Chemistry, 2010, 183 (9), pp 2190-2195
Journal of Solid State Chemistry, Volume 183, Issue 9, p. 2190-2195
www.slideshare.net/johader