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Process Design for Plasma-Based Gas-Phase Nucleation of Carbon Nanoparticles

Cole, Jonathan
http://rave.ohiolink.edu/etdc/view?acc_num=case1512779018930462

Abstract Details

2018, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
This thesis project is focused on designing plasma processes for the controlled synthesis of nanoscale forms of crystalline carbon. The general mechanism for all the plasma systems is homogeneous nucleation, which describes the formation of nanoparticles in the gas-phase from vapor precursors. Nucleation from a preexisting seed particle is also explored, which is similar to heterogeneous nucleation on a substrate except that in some cases nucleation of the seed itself occurs within a gas flow. The first type of plasma system that was studied is a direct-current (DC), atmospheric-pressure microplasma that effectively limits particle growth so that nanosized (<10 nm) particles are synthesized. However, this plasma is limited in volume and requires metal electrodes that could produce impurities. For this reason, the second type of plasma system is a radio-frequency capacitively-coupled plasma (RF CCP), where the excitation of the plasma occurs with two metal electrodes on the outside of a quartz tube, eliminating contact with metal. This was studied in two variations, one at low pressure with a large plasma volume and, therefore, greater throughput, and one at atmospheric-pressure. To scale-up nanoparticle throughput at atmospheric-pressure, a high-voltage, alternating current, coaxial dielectric barrier discharge (DBD) was also studied. Characterization by Raman spectroscopy and transmission electron microscopy of the nanoparticles synthesized from different precursors in the various plasma systems is presented. The different processes were found to produce distinct materials, with the DC microplasma producing small quantities of diamond but a majority of mixed sp2 and sp3 phases of carbon. The RF CCP processes, meanwhile, produced more graphitic material, including onion-like carbon. Seeded growth by coinjection of methane and silane yielded cubic crystalline silicon carbide nanoparticles instead of diamond, but preexisting silicon nanoparticles produced by RF CCP were demonstrated with microwave plasma-enhanced chemical vapor deposition to be suitable seeds for diamond nucleation and also for photoluminescent silicon-vacancy defect centers in diamond. Scale-up of particle throughput in atmospheric-pressure plasma reactors was accomplished using two DBD reactors with different plasma volumes. These were found to produce comparable particle size distributions under some conditions while also maintaining comparable gas breakdown voltages.
Mohan Sankaran (Advisor)
Heidi Martin (Committee Member)
Donald Feke (Committee Member)
Giuseppe Strangi (Committee Member)
146 p.
Chemical Engineering; Materials Science

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Citations

  • Cole, J. (2018). Process Design for Plasma-Based Gas-Phase Nucleation of Carbon Nanoparticles [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1512779018930462

    APA Style (7th edition)

  • Cole, Jonathan. Process Design for Plasma-Based Gas-Phase Nucleation of Carbon Nanoparticles. 2018. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1512779018930462.

    MLA Style (8th edition)

  • Cole, Jonathan. "Process Design for Plasma-Based Gas-Phase Nucleation of Carbon Nanoparticles." Doctoral dissertation, Case Western Reserve University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512779018930462

    Chicago Manual of Style (17th edition)

case1512779018930462
699
© 2018, some rights reserved.Creative Commons License Process Design for Plasma-Based Gas-Phase Nucleation of Carbon Nanoparticles by Jonathan Cole is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.