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Plasma Generated Nano - Particles

Plasma Generated Nano - Particles . By Maurice Clark For Elec 7730 Fall 2003. Outline. Glossary Questions Nano Particle Generation Thermal Plasma Atmospheric Pressure Plasma Discharge Radio Frequency Plasma Conclusion Answers. Questions.

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Plasma Generated Nano - Particles

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  1. Plasma Generated Nano - Particles By Maurice Clark For Elec 7730 Fall 2003

  2. Outline • Glossary • Questions • Nano Particle Generation • Thermal Plasma • Atmospheric Pressure Plasma Discharge • Radio Frequency Plasma • Conclusion • Answers

  3. Questions • What types of plasma can be used to generate nanoparticles? • Name one way that particle size can be controlled in thermal plasma. • What are the advantages of using the DMP reactor?

  4. Glossary • Coagulation-the process by which particles collide and adhere to one another to form larger particles. • Agglomerated- clustered together but no coherent. • HPPD-Hypersonic Plasma Particle Deposition

  5. Thermal Plasma

  6. Thermal Plasma • Thermal Plasma Generation • Gas Discharge Between two Electrodes • Microwave Frequency • RF Radio Frequency • Capacitive • Inductively • High Intensity Arc Discharge Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003

  7. Thermal Plasma High Pressure Plasma Low Pressure Plasma

  8. Thermal Plasma • Conditions • At or near Atmospheric Pressure • Temperature of the Ions and Neutrals are almost identical to the electron temperature (i.e. they are in or close to thermodynamic equilibrium) • Electron Density of the plasma is very high in thermal plasma

  9. Thermal Plasma • DC Thermal Plasma used to generate Al Nanoparticles. • Precursor Gases • Solid AlCl 3 is heated to 350K • Argon is main plasma gas with a fraction of Hydrogen to ensure the complete conversion of chloride vapor reactants to HCl http://www.me.umn.edu/courses/me8362/Bin_Zhang.pdf

  10. Thermal Plasma • The high temperatures of the plasma gases assist in the complete dissociation of reactants into their elemental forms. • Cooler regions, which exist due to the presence of steep temperature gradients lead to homogeneous particle nucleation • Homogeneous particle nucleation evolves physical condensation of supersaturated vapor. • Growth of clusters to critical size can occurs with or without the presents of ions as nucleation sites. http://www.me.umn.edu/courses/me8362/Bin_Zhang.pdf

  11. Thermal Plasma • Residence Time • Small residence time leads to the formation of smaller nanoparticles. • Higher residence time leads to the formation of larger size nanoparticles. • Particle growth can be regulated by adjusting • The input power • Injection flow rate • Counter flow gases http://www.me.umn.edu/courses/me8362/Bin_Zhang.pdf

  12. Thermal Plasma • Synthesis Process • Metallic particles are nucleated in the plasma stream • A quenching gas which contains a small amount of oxygen is used to passivate and quench the growth of the nanoparticles. • Depending on the condition and reactants particles may nucleate near downstream nozzle or shortly past the nozzle exit. http://www.me.umn.edu/courses/me8362/Bin_Zhang.pdf

  13. HPPD Apparatus • Setup for depositing a continuous film • Current 250 A • Power 10KW • Main Plasma Gases • Argon • Hydrogen • Gases Reactants for nanoparticles deposition are injected up stream. http://www.me.umn.edu/courses/me8362/Rajesh_Mukherjee.pdf

  14. HPPD Apparatus • Ar/H2 plasma provides the high heat of reaction for the nucleation of nanoparticles from gaseous precursors. • The temperature of the plasma gases reaches about 5000K • The thrust produced by the tremendous volume expansion helps to completely dissociate Silicon tetrachloride and methane • Helps with subsequent nucleation of silicon nanoparticles. • The carbide is believed go form from the dissociation of methane into the silicon nanoparticles. http://www.me.umn.edu/courses/me8362/Rajesh_Mukherjee.pdf

  15. HPPD Apparatus • Residence for a 20nm particle (between the nozzle and substrate) is only about 20us. • Average velocity is 2000m/s over the 2mm distance • Average particle size decreases with decreasing pressure. http://www.me.umn.edu/courses/me8362/Rajesh_Mukherjee.pdf

  16. Thermal Plasma b) SEM Ti/TiC Composite Film a) SEM micrograph of Silicon Carbide Film http://www.me.umn.edu/courses/me8362/Rajesh_Mukherjee.pdf

  17. Thermal Plasma High resolution SEM image Showing nano scale grain Size same film as below SEM image of a cross section of SiC film. Pressure 150 Torr, substrate temp 730 C, SiCl4 flow rate is 67 sccm deposition time was 6 mins F. Liao, S. Park, J. M. Larson, M. R. Zachariah, S. L. Girshick, Mater. Lett 57 pg 1982 2003

  18. R.F. Coupled PlasmaSynthesis of Nano-Particles

  19. R. F. Inductively Coupled Plasma • Si nanoparticles formation from pure silane plasma and Ar and H dilutions • 3x10-6 mTorr • Operating Pressure is between 1-500 mTorr • RF Field • A four turn flat spherical coil made of quarter inch copper tubes. Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003

  20. R. F. Inductively Coupled Plasma • Three Regimes of Growth • No observable particles growth • Low pressure (below 8 mtorr) • Highly monodispersed particles • For higher pressures where the plasma on time is below a threshold value. • Polydisperse and agglomerated particles • Plasma on time exceeds threshold value Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell,J. Appli Physi Vol 94 (4) pg 2277 2003

  21. R. F. Inductively Coupled Plasma • Pressure 12mtorr and plasma of time of 100s. b) Pressure of 80mtorr and plasma on time of 10s. Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003

  22. R. F. Inductively Coupled Plasma • Particle Growth can be controlled by controlling the plasma on time. • Two Phases to Particle growth • Coagulation • First 10 sec • Surface Deposition Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003

  23. R. F. Inductively Coupled Plasma • Electro Statically Trapped Particles (Explain the where the mono and polydisperse meet) • Large Particles are swept out through neutral gas or ion drag forces. • Reduction in the number of particles from the plasma, in turn, allows the radical density to increase. • Once the radical density reaches a threshold value for nucleation a second generation of particles can form through nucleation and subsequent coagulation of very small particles. Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003

  24. R. F. Inductively Coupled Plasma Argon/Silane Plasma - + - 0-15 sec 5nm Coagulation 15 - 40 sec 5 - 33nm Coagulation Stops And the Particles Continue to grow By surface deposition Z. Shen and U. Kortshagen, J. Vac. Sci. Technol A 20 (1) Jan/Feb 2002

  25. Atmospheric Pressure Discharge

  26. Atmospheric Pressure Discharge • Hybrid iron and iron oxide / carbon based nanoparticles composites were synthesized. • Conditions • 200ml benzene • 100-300V • Current 1-3 A • Angular speed of electrode 1000-3000 rpm • Plasma gas Ar flow rate is equal to 6 sccm • Treatment time 6 mins F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003

  27. Atmospheric Pressure Discharge • DMP reactor • Allows the initiation and sustaining of discharges in atmospheric pressure environments to coexist with the liquid/ vapor mediums. F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003

  28. Atmospheric Pressure Discharge • Spirally arranged pin system acts as a source of the high current density field emission arc source. • Under DC or AC voltage conditions many micro discharges will cover the entire electrode. • Rotating Electrode • Spatially homogenizes the multiple micro arcs • Pumps fresh liquid and vapor into the discharge zone • Thin the boundary lay between the emission tips and the rest of the liquid. F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003

  29. Atmospheric Pressure Discharge • It is believe that the derivatives are the intermediate structures which led to further recombination mechanisms to the formation of Carbon-based solid state and benzene-insoluble nanoparticles systems F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003

  30. Atmospheric Pressure Discharge F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003

  31. Conclusion • A variety of Plasma’s can be used to generate Nanoparticles

  32. References • http://www.me.umn.edu/courses/me8362/Bin_Zhang.pdf • http://www.me.umn.edu/courses/me8362/Rajesh_Mukherjee.pdf • F. S. Denes, S. Manblache, Y. C. Ma, V. Shamamian, B.Ravel and S. Prokes, J. Applied Physics vol 94 (5) 2003 • Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277 2003 • F. Liao, S. Park, J. M. Larson, M. R. Zachariah, S. L. Girshick, Mater. Lett 57 pg 1982 2003 • Z. Shen and U. Kortshagen, J. Vac. Sci. Technol A 20 (1) Jan/Feb 2002

  33. Answers • Three methods for generating nanoparticles are thermal, Atmospheric Pressure Discharge, and R.F Plasma. • Particle size can be controlled in a thermal plasma by increasing the flow rate of the quenching gas. • Allows the initiation and sustaining of discharges in atmospheric pressure environments to coexist with the liquid/ vapor mediums.

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