Plasma-molten Metal and/or Liquid Interactions for Materials/Chemical Processing

Several grand challenges in energy storage and conversion need the discovery of functional materials that many agree will be composed of complex compositions at nanoscale. In this regard, plasma based materials processing has been shown to be promising for combinatorial techniques and scalable processing. The use of plasma oxidation of liquid precursors allows for creation of metastable complex oxide particles with compositional control.1 A number of examples will be discussed in which the above two techniques are currently being used for accelerating the development of a variety of catalysts including electrocatalysts and materials for storage applications. This talk will highlight our efforts to understand the role of plasmas under two categories: (a) the synergistic effects hydrogen and nitrogen plasma interactions with molten metals;2 and (b) the oxygen plasma-liquid droplet interactions.3 To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas. In the case of oxygen plasma-liquid droplet interactions for creating complex oxides, the role of solvated electrons, oxygen radicals and heating effects will be discussed. Finally, the use of plasmas for achieving liquid phase epitaxial growth of GaN and related materials will be discussed.4 Author acknowledge primary funding support from NSF Solar Project (DMS 1125909), and NSF EPSCoR (1355438). References 1. P. Ajayi, S. Kumari, D. Jaramillo-Cabanzo, J. Spurgeon, J. Jasinski and M.K. Sunkara, “A rapid and scalable method for making mixed metal oxide alloys for enabling accelerated materials discovery”, J. of Materials Research, 31 (11), 1596-1607(2016) 2. L. Carreon, D.F. Jaramillo-Cabanzo, I. Chaudhuri, M. Menon and M.K. Sunkara, “Synergistic interactions of H2 and N2 with molten gallium in the presence of plasma”, Journal of Vacuum Science and Technology A, 36, 021303 (2018). 3. P. Ajayi, M. Z. Akram, W. H. Paxton, J. B. Jasinski and M. K. Sunkara, “Nucleation and Growth Mechanisms During Complex Oxide Formation Using Plasma Oxidation of Liquid Precursors”, Submitted (2019) 4. Jaramillo, J. Jasinski and M. Sunkara, “Liquid Phase Epitaxial Growth of Gallium Nitride”, Crystal Growth and Design, 19, 11, 6577-6585(2019)