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