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Timothy M. Banks
Raman Spectroscopy study and Raman Spectroscopy study and NanoIndentor study on the effects NanoIndentor study on the effects
of high pressures on of high pressures on
Hexagonal Boron NitrideHexagonal Boron Nitride
ExperimentExperiment
• PurposePurpose
• BackgroundBackground
• TechniquesTechniques
• Results Results
PurposePurpose
• Super-hard materialSuper-hard material
• Determine Raman Scattering effectsDetermine Raman Scattering effects
• Determine hardness Determine hardness
Diamond Anvil CellDiamond Anvil Cell
• ApplicationsApplications
• VarietiesVarieties
• Alabama CellAlabama Cell
Diamond Anvil CellDiamond Anvil Cell
Raman SpectroscopyRaman Spectroscopy
• Raman Effect
• C.V. Raman
• Rayleigh scattering
• Photons
Hexagonal Boron Nitride
• “White Graphite”
• First discovered in 19th century
• Chemical composition
Hexagonal Boron NitrideHexagonal Boron Nitride
• APPLICATIONS– Industrial– Cosmetic– Chemical
Hexagonal Boron Nitride
SEM-image (secondary electron image) of hexagonal boron nitride.
Experimental Procedure
• Prepare Gasket
• Pressure MeasurementP=380.8 [ ]5-1)GPa
• Raman Spectra
• NanoIndenter XP
0
Pressures Reached
• 8 GPa (L1)
• 42 GPa (L2)
• 29 GPa (L3)
• 13 GPa (L4)
Pressure vs. Photon Energy
Pressure dependence of Raman-active Phonons in hBN
y = 3.8068x + 1368.9
R2 = 0.9928
1360
1370
1380
1390
1400
1410
1420
1430
0 5 10 15
Pressure (GPa)
Ph
on
on
En
erg
y (
cm
-1)
L1
L2
L3
L4
Linear (L4)
Pressure dependence of Raman-active Phonons in hBN
y = 3.8068x + 1368.9
R2 = 0.9928
1360
1370
1380
1390
1400
1410
1420
1430
0 5 10 15
Pressure (GPa)
Ph
on
on
En
erg
y (
cm
-1)
L1
L2
L3
L4
Linear (L4)
Results
• Raman Spectra
• Spring Constant
• NanoIndentor Results
Spring Constant vs. Pressurek vs. P
y = -0.1471x2 + 8.9174x + 1367.7
R2 = 0.97461.36E+03
1.38E+03
1.40E+03
1.42E+03
1.44E+03
1.46E+03
1.48E+03
0 2 4 6 8 10 12 14
Pressure (GPa)
k=
w^
2m
(K
g/s
2 )
k=w^2m
Poly. (k=w^2m)
Summary & Conclusions
• Raman Scattering
• Hardness
Acknowledgements
• It is with great pride and gratitude that I would like to thank the following for their guidance and support: Dr. Yogesh K. Vohra, Nenad Velisavljevic, Reed Patterson, Ginger Hughes, UAB Physics Department, and the National Science Foundation.
The EndThe End
Thank YouThank You