Alumna Rost to Present Seminar on Entropically-Stabilized Oxides

Posted on 2/19/2015 5:51:04 PM

On Friday, February 20, 2015, Christina Rost of North Carolina State University Department of Materials Science and Engineering will present a seminar, “Entropically-Stabilized Oxides: Exploring a Novel Class of Multi-component Materials” at 2:30 p.m. in Weyandt Hall, room 331.

Rost is a 2012 graduate of the Department of Physics at Indiana University of Pennsylvania.

Abstract:

We demonstrate a novel class of entropy stabilized oxides, characterized by configurational disorder of the cation species in an oxygen sub-lattice and exhibiting an unusual degree of structural perfection. Currently, we have demonstrated this phase phenomenon with several different compositions. The simplest composition is of rocksalt structure, containing equal amounts of Mg, Co, Cu, Ni and Zn. More complex structures include spinel, and contain Mg-Ti-Fe-Cu-Zn and Ni-Ti-Ga-Cu-Zn, among others. Bulk ceramics are synthesized through solid state sintering above 875°C in air, while thin films are grown via pulsed laser deposition with a controllable variability between polycrystalline and epitaxial structures-single crystal, heteroepitaxial layers are grown on (100) MgO substrates.

In this talk, fundamental questions are addressed. We show the entropic dependence of our solid solutions by examining the phase transformation temperature as a function of stoichiometry. Energy dispersive spectroscopy and x-ray absorption fine structure reveal the degree of localized disorder within the lattice. Collectively, these new materials display genuine entropic stabilization and promote new potentials for complex oxide systems.

All are welcome to attend. Light refreshments will be served.