Atomic structure at the nanoscale a 21st century materials challenge

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Recently: nanocrystalline materials

Lanthanum Aluminate glass

J. Du and L.R. Corales, J. Non-Cryst. Solids (2007)

APPROACH

Slide 9

Pair Distribution Function from total scattering experiments

Raw data

Structure function

PDF

APPROACH

Slide 10

How can we get short range structural information?

Pair Distribution Function from total scattering experiments

APPROACH

Slide 11

Pair Distribution Function: info on different lengthscales

Strength of the Pair Distribution Function

APPROACH

Slide 12

PDF primer: C60

Pair Distribution Function: info on different lengthscales

APPROACH

Slide 13

Pair Distribution Function: Q-space resolution effect

APPROACH

Slide 14

Pair Distribution Function: rapid data collection mode

Rapid Acquisition PDF (RAPDF) at a synchrotoron:

Measuring PDFs in a few seconds

P. Chupas et al, J. Appl. Cryst. 36, 1342-1347 (2003).

APPROACH

Slide 15

Pair Distribution Function: rapid data collection mode

P. Chupas et al, J. Appl. Cryst. 40, 463-470 (2007).

Application of a large-area, high-sensitivity, fast readout,

flat-panel GE detector based on an amorphous silicon

Nickel data, 0.03s collection time, Qmax 28 Å-1

APPROACH

Slide 16

Pair Distribution Function: modeling

Ni

300K Ni data from GPPD at IPNS, ANL

data

difference

model

PDF Programs

PDFgetX1

PDFgetN1

PDFgui2 (PDFfit)

1 http://nirt.pa.msu.edu

2 http://www.diffpy.org/

APPROACH

Slide 17

Nanometer scale structure of CuIr2S4

Local structural aspects of the metal-insulator transition

in CuIr2S4

- X-ray total scattering study -

Collaboration with: J.F. Mitchell, MSD, Argonne Nat. Lab.

Credits: Y.S. Hor, A.S. Masadeh, H.J. Kim, P. Juhas, S.J.L. Billinge

HIGHLIGHT

Slide 18

HIGHLIGHT

The role of lattice geometry – frustration

Spinel structure: AB2X4 Crystallizes in the cubic (isometric) crystal system B-sublattice – pyrochlore – corner-shared tetrahedra This sublattice promotes frustration, interesting physics arises in spin (AF interactions) and charge (half-integer valence) sectors!