Synthesis and Characterization of Au-Zn Nanoparticle Implants in

SapphireDaniel Scott, Emmanuel Epie, Wei-Kan Chu

Department of Physics, Texas Center for SuperconductivityUniversity of Houston

Presented at CAARI 2016

Background

● Abundant ongoing research in nanomaterials○ Many factors affect nanoparticle properties (size, structure, material, distribution)

● Applications○ Sensors, imagers, optical switches

● Little to no material on Au-Zn NP alloys

● Can a Au-Zn NP alloy be synthesized via dual ion implantation in sapphire? What mechanisms exist to alter the optical properties of these NP?

Background (continued)

● Surface Plasmon Resonance (SPR)○ Oscillation of conduction electrons

○ Impacted by dielectric (particle & ambient), structure, size

● Track formation may impact nanoparticle growth1

○ Implantation order (Au+Zn or Zn+Au) may lead to different results

● Annealing may offer control of optical responses:○ Alloy (phase and structure)○ NP size

1Wang, Jun, et al. (See References)

Method

● Implantation of Au- and ZnO- ions in sapphire (Al2O3)

● Samples for: Au, Zn, Au+Zn, Zn+Au

● Optical measurements via spectrophotometer○ Cary 5000 UV-vis-23 NIR spectrophotometer

● Annealings under Ar in a quartz tube

● NP size estimates by GIXRD○ D/Max-RA X-ray spectrometer (Rigaku)

Parameters

● 60 keV (Au and ZnO)

● For adequate track formation:1○ Au (Fluence 3x1016 / cm2)

○ Zn (Fluence 2.5x1016 / cm2)

● SRIM2 (range, sputtering, etc.)

● Two hour annealings at:○ 400°C & 600°C

Concentration vs depth created using formula from 1 Wang, Jun, et al.

Unannealed Samples

Absorbance peaks:

Zn N/A

Au 552 nm

Au+Zn 530 nm

Zn+Au 434 nm

Annealing (Zn+Au)

SPR Peaks:

Unannealed 434 nm

400°C 514 nm

600°C 549 nm

Annealing (Au+Zn)

SPR Peaks:

Unannealed 530 nm

400°C 530 nm

600°C 531 nm

Data

SPR Peaks Au Au+Zn Zn+Au

Unannealed 552 nm 530 nm 434 nm

400°C 553 nm 530 nm 514 nm

600°C 558 nm 531 nm 549 nm

Analysis

● Possible explanations of shift:

○ Change in ambient dielectric○ Crystalline stress○ NP size○ Alloy formation

Dielectric/Stress?

Could these account for the results?

○ In both cases, look towards differences in Zn+Au and Au+Zn

Peak

Au 552 nm

Au+Zn 530 nm

Zn+Au 434 nm

Size?

Approximate nanoparticle sizes (diameter) as determined by GIXRD and Debye-Scherrer Formula

Diameters Au Au+Zn Zn+Au

Unannealed 2.7 nm 1.7 nm 2.2 nm

400°C 2.7 nm 1.9 nm 3.1 nm

600°C 2.8 nm 2.2 nm 3.8 nm

*Note: Machine broadening not accounted for. Sizes are taken as approximations, not exact, and are mostuseful in showing the relative differences in size between samples. Diameters are lower bounds.

DDSCAT3

Simulated Peak Absorbance Au in Sapphire

r = 1 nm 558 nm

r = 2 nm 559 nm

r = 4 nm 560 nm

Recall:Experimental absorbance peak of Au Sample: 552 nm

Conclusion:

Key Results:● Optical responses manipulatable through annealing● Implantation order affects material synthesized● Synthesis of Au-Zn metallic nanoparticle alloy

○ Dielectric, size, and stress do not explain results

Future Research:● TEM● Nanoparticle structural analysis● Attempt at confirming alloy formation and identifying particular alloy

Peak

Au 552 nm

Au+Zn 530 nm

Zn+Au 434 nm

References

1 Wang, Jun, Guangyi Jia, Bei Zhang, Huixian Liu, and Changlong Liu. "Formation and Optical Absorption Property of Nanometer Metallic

Colloids in Zn and Ag Dually Implanted Silica: Synthesis of the Modified Ag Nanoparticles." J. Appl. Phys. Journal of Applied Physics 113.3 (2013): 034304.

2 SRIM, the stopping and range of ions in matter (2008) by J. F. Ziegler, J. P. Biersack, Matthias D. Ziegler

3 Draine, B.T., & Flatau, P.J., "Discrete dipole approximation for scattering calculations", J. Opt. Soc. Am. A, 11, 1491-1499 (1994)

Acknowledgements

Department of Physics & Texas Center for Superconductivity (University of Houston)

Faculty Mentor: Dr. Wei-Kan Chu

Co-author: Emmanuel Epie