Transcript No Slide Title

Structure of ZnO Nanorods
using X-ray Diffraction
Marci Howdyshell
Albion College
Mentors: Bridget Ingham
and Michael Toney
Introduction
• What?
– Zinc Oxide (ZnO)
• Why?
– Future applications of ZnO such as chemical
sensing and optoelectronics
– The nanostructures enhance bulk
characteristics
– The crystal structures of nanorods affect
different properties
– We can look at orientations
• How?
– X-ray diffraction!
The experiment
Schematic diagram of experimental setup: CE is counter
electrode; RE is reference electrode. -The
electrochemistry is controlled as the x-ray beam reflects
off the top of the quartz rod (working electrode) and onto
the detector.
1/2 O2 + H2O + 2e - --> 2OH Zn2+ + 2OH - --> ZnO + 2 H2O
Diffraction Pattern
ZnO (102)
nλ = 2dsin(θ)
(Q = 2π/d)
ZnO (102)
Making some sense
of it
ZnO
(102)
Making some sense of it:
Intensity vs.  Plots
Au (111)
ZnO (002)
ZnO (102)
ZnO (101)
ZnO (102) Peak
Width
•Width corresponds with
how much the grain direction
varies about the midpoint.
•Less negative potential
means greater width and
therefore more variation of
grains about the midpoint
Potential (mV vs. Ag/AgCl/KCl
Growth of ZnO
Nanostructures
More negative: thicker
Less negative: thinner
Less negative potentials
(-370 mV)
More negative potentials
(-970 mV)
SEM Images
-970 mV
-770 mV
-670 mV
-370 mV
65°C, 5mM Zinc Nitrate,0.1M KCl
Future Analysis
• Complement with
electron microscopy
• Time series;
modeling
• XANES/EXAFS*
B. Ingham, B. N. Illy, J. R. Mackay, S. P. White,
S.C. Hendy, M. P. Ryan, Mat. Res. Soc. Symp.
Proc. 1017 (2007) DD12.16
B. Ingham, B. N. Illy and M. P. Ryan, J. Phys.
Chem. C (submitted)
Acknowledgements
• Bridget Ingham, Michael Toney (SSRL)
• Benoit Illy and Mary Ryan (Imperial
College London)
• DOE, SULI Program Coordinators