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# Brent J. Heuser <bheuser@uic.edu>
# requesting 4 days, at minimum=3 days
# beamline 34ID-E, Microdiffraction measurements of hydride particles in Pd to quantify lnear-surface ocal strain
# instrument 34ID-E microbeam
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# top:/home/www/beamtime-requests/req01074.txt
# UNICAT Member Beam Time Request  #1074
# created Mon Dec 11 12:44:27 CST 2006
####################################################

apsrun:
	2007-01

beamline:
	34ID-E

collaboration:
	No

collaborator_Wenjun:
	ON

contact:
	bheuser@uic.edu

days:
	4

description:
	We are interested in the a direct measurement of lattice strain associated with a single hydride particle embedded in a Pd matrix.  We have a good idea of the particle morphology from  small-angle neutron scattering measurements on single crystal Pd.  The hydride particles are initial very small plates  20 A thick.  As the system Pd-H crosses the miscibility gap, the plates grow to sizes of order 1 to 10 microns.  These plates have a (100) habit plane that minimizes the hydrostatic stress associated with the volumetric dilitation of the hydride particle.  These plates initially nucleate at the surface and grow inward.  We are interested  in the evolution of the lattice strain near the surface both in the Pd matrix and in the hydride particles during growth of the hydride particles.  We believe the local strains can be quantified in a 2-D microdiffraction experiment.  The sub-micron spatial resolution of the lattice strain will be adequate.

The samples will be polycrystalline and electropolished.  We can control the grain size of the polycrystalline samples by a cold work-anneal procedure.  We have an environmental gas cell that will fit in the space between the 34-ID-E detector and incident collimation system.  We will perform 2-D strain measurements (without the differential wire scanning) at first since we do not currently have the ability to scan a wire across our sample as it is contained in our environmental cell.  Should the 2-D strain measurements prove to be successful, we will consider modification of our cell to permit 3-D strain mapping.

equipment_required:
	Turbo pump station

experiment:
	Microdiffraction measurements of hydride particles in Pd to quantify lnear-surface ocal strain

foreign_nationals:
	Kun Mo

hazards:
	We will perform in situ hydrogen gas exposure at room temperature with gas pressure less than 50 Torr in a volume less that 500 ml.  We have an environmental gas cell with a welded Be window that has the necessary gas and pumping ports.

instrument:
	34ID-E microbeam

instrument_other:
	

minimumdays:
	3

name:
	Brent J. Heuser

nonmembers:
	

submit:
	Submit

unacceptable_dates:
	

z34ID_change_undulator:
	no

z34ID_details:
	

z34ID_parasitic:
	yes


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