1. Ion implantation induced formation of aluminum nanoparticles inalumina via reduction E.M. Hunt , J.M. Hampikian , D.B. Poker , N.D. Evans Presentation by: Younes Sina

2. Colloid formation mechanism: Ion implantation Precipitation of the implanted ion(s) & formation of nanocrystals at high temperature during implantation or post-implantation annealing Irradiation –induced dissociation of the host material Metal particle formation due to electron or neutron irradiation of alkali halides (LiF), alkaline earth fluorides (CaF2), and some oxides (Lithia LiO, Alumina Al2O3) e 14 MeV e LiF Li (colloid) Al2O3 Al slightly elevated temperature 1 MeV e 1 MeV e LiO2 Li (colloid) Al2O3 Al thin film elevated temperature

3. 1500 ⁰C 80 h Removing residual polishing damage

4. 5x1016 Ca+/cm2 Vacuum 1x10-7Torr 0.5-2 mA 50 keV 70 keV

5. 5x1016Y+/cm2 Vacuum 1x10-7 0.5-2 mA 150 keV

6. Equipments used for the results: TEM Knoop microhardness Rutherford backscattering Energy Filtered TEM (EFTEM) Differential optical absorption Energy Dispersive X-ray Spectroscopy (EDS) High Resolution Parallel detector Electron Energy Loss Spectroscopy (PEELS)

7. 50 keV 5x1016 Ca+/cm2 70 keV 5x1016 Ca+/cm2 ~30nm ~40 nm Experimental implanted ion range Experimental implanted ion range Experimental implanted ion range Ca 14% Ca 10% 150 keV 5x1016 Y+/cm2 ~41 nm Experimental implanted ion range Y 9% Amorphous layer =120 nm

8. Rutherford backscattering The implanted ion range predictions made by PROFILE simulation program were reasonably accurate.

9. Knoop microhardness Ca 50 Y 1 50 Ca 70 Implanted hardness <1 Unimplanted hardness

10. ? Differential optical absorption by High Resolution TEM Optical absorption spectra from the implanted samples, showing the absorption feature caused by the presence of metallic colloids dispersed in the matrix. ?

11. TEM Lattice parameter of pure FCC aluminum= 0.40497 nm 0.410±0.004 nm 10.7±1.8 nm TEM micrograph of 150 keV Y+ implantation 0.413±0.004 nm 8.8±1.2 nm TEM micrograph of 50 keV Ca+ implantation 0.409±0.004 nm 7.5±1.4 nm TEM micrograph of 70 keV Ca+ implantation

12. From: High Resolution Parallel detector Electron Energy Loss Spectroscopy (PEELS) Energy loss spectra from 150 keV Y+ Energy loss spectra from 70 keV Ca+ Alumina Plasmon loss @ 25 eV Metallic aluminum Plasmon @ 15 eV

13. Energy Dispersive X-ray Spectroscopy (EDS) Chemical analysis of the 3 samples using Energy Dispersive X-ray Spectroscopy (EDS) indicates that the particles are aluminum-rich with respect to the surrounding matrix. There is no graph or more information about EDS !!!!!??????

14. Energy Filtered TEM (EFTEM) micrographs of the 50-keV Ca+ implantation 15-eV-loss image particles in the implanted areas appear bright This set of images confirms that the particles contain metallic aluminum 25-eV-loss image particles in the implanted areas appear dark Elemental map of oxygen from an adjacent region particles are oxygen deficient with respect to the surrounding matrix

15. Mie theory for absorption by small metal particles Wavelength at maximum absorption (λ peak) due to colloidal metal particles width of absorption peak: ωp =Plasmon frequency of the bulk metal ω0 =Collision frequency of the electron in the metal

16. Theoretical calculation: From Eq. (1): λ peak=218 nm using ε₀=1 n0 =1.76 ω₀ =2.309x1016 s-1 Implantation of ions into the matrix materials will increase the index of refraction (n0) in the surface region Increase of n0 =1.76 to 1.96 results in a calculated λ peak=240 nm

17. ? Different behavior of Ca Alumina is known to be difficult to fully amorphize except with large doses of heavy ions and/or implantation at reduced temperatures Zn & Zr (strongly oxidizing elements) produce buried amorphous layers in alumina with much greater accelerating energies or a much higher fluence.

18. Reduction of target cation with ion (that is more oxygen reactive) G<0 2 Y+ Al2O3 2 Al+ Y2O3 3 Ca+ Al2O3 2Al+ 3CaO G<0

19. Kurdistan, Iran