|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Hume-Rothery Award Symposium: Thermodynamics of Materials
||X-ray and Neutron Scattering Studies of Lattice Vibrations and Thermodynamic Phase Stability in Vanadium Dioxide
||John D Budai, Jiawang Hong, Olivier Delaire, Michael Manley, Chen Li, Jonathan Tischler, Ayman Said, Bogdan Leu, Douglas Abernathy, Eliot Specht, Lynn Boatner
|On-Site Speaker (Planned)
||John D Budai
Vanadium dioxide is a strongly correlated material that exhibits a metal-insulator transition (MIT) coupled with a structural transition just above room temperature. To shed light on mechanisms controlling changes in electrical and structural properties, we have combined x-ray and neutron inelastic and diffuse scattering measurements with first principles molecular dynamics calculations. We find good agreement between experimental measurements and theoretical predictions, and the results help identify physical mechanisms driving the MIT. Our studies reveal that changes in the lattice dynamics across the transition are responsible for most of the total entropy change, that is, the entropy change is dominated by vibrational rather than electronic contributions. In addition, we observe strongly anharmonic phonons across a wide region of reciprocal space in the metallic phase, and conclude that these short-lived, low-energy phonons are responsible for thermodynamically stabilizing the metallic phase at high temperatures.
Supported by Materials Sciences and Engineering Division, U.S. DOE-BES.
||Planned: A print-only volume