The Surface Kinetics of the Initial Stages of Cu and Cu Alloy Oxidation
Professor Judith C. Yang
Mechanical Engineering and Materials Science
University of Pittsburgh
Wednesday, March 9, 2011
11:00 am – 12:00 pm
Fung Auditorium
Abstract:
We are studying the dynamics of the initial and transient oxidation stages of a metal and alloys with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) and complemented with first principles theoretical simulations and kinetic Monte Carlo (KMC). We have previously demonstrated that the formation of epitaxial Cu2O islands during the transient oxidation of Cu(100), (110) and (111) films bear a striking resemblance to heteroepitaxy, where the initial stages of growth are dominated by oxygen surface diffusion and strain impacts the evolution of the oxide morphologies. We are developing a KMC code (thin film oxidation, TFOx) that simulates the variety of surface interactions on Cu(001) where first principle calculations are used to provide the input parameters to TFOx. We are presently investigating the early stages of oxidation of Cu-Au and Cu-Ni as a function of oxygen partial pressures and temperatures. For Cu-Au oxidation, the oxidation mechanisms change where the Cu2O reveals a dendritic growth. For Cu-Ni oxidation, the addition of Ni causes the formation Cu2O and/or NiO where the oxide type(s) and the relative orientation with the film depend on the Ni concentration, oxygen partial pressure and temperature.
Biosketch:
Biographical Sketch. Professor Judith C Yang received her PhD in physics from Cornell University in 1993. She then went to the Max-Planck-Institute of Metallforschung, Stuttgart, Germany as a post-doctoral fellow. In 1995, she returned to the US as a postdoc and visiting lecturer to the Materials Research Laboratory, U. Illinois at UrbanaChampaign. In 1999, she joined the materials science and engineering faculty at U. Pittsburgh. She has authored or co-authored ~60 journal publications and given ~90 invited talks. She is the 2002 recipient of the NSF career award, 2004 B.P. America Faculty fellowship, and the 2005 Chancellor’s Distinguished Research Award. Since 2010, she is a Professor in Chemical and Petroleum Engineering; she has a secondary appointment in physics. Her research areas include oxidation, heterogeneous catalysis, nano-materials, gas-surface reactions, and transmission electron microscopy, especially in situ.