Patrick has been selected to receive an award from the Young Investigator Program of the Office of Naval Research.  The ONR YIP seeks to identify and support academic scientists and engineers who are in their first or second full-time tenure-track or tenure-track-equivalent academic appointment and for FY13, have begun their first appointment on or after Nov. 1, 2007, and who show exceptional promise for doing creative research. The program’s objectives are to attract outstanding faculty members of Institutions of Higher Education to the Department of Navy’s (DoN’s) research program, to support their research, and to encourage their teaching and research careers. Patrick’s proposed research is focused on developing the ability to measure the thermal boundary conductance, or Kapitza conductance, across the interface of a solid and a low thermal conductivity fluid, along with developing simultaneous diagnostics to measure the solid/fluid interfacial pressure and wetting.  This work will establish the relationship between nanoscale surface roughness, chemistry, and wetting on heat transport processes across solid/fluid interfaces via novel experimental measurements.

The title of the awarded project is “Surface chemistry and geometry effects on nanoscopic heat transfer processes at solid/fluid interfaces.”

The official announcement can be found here:  http://www.onr.navy.mil/en/Science-Technology/Directorates/office-research-discovery-invention/Sponsored-Research/YIP/2013-young-investigator-recipients-YIP.aspx

Our paper examining the effects of coherent domain walls on the thermal conductivity of bismuth ferrite (BiFeO3) was published in Applied Physics Letters (Appl. Phys. Lett. 102, 121903 (2013)). We show that coherent domain walls can scatter phonons as effectively as incoherent grain boundaries, opening up a new regime of strain engineering of phonon transport.

Abstract

Ferroelectric and ferroelastic domain structure has a profound effect on the piezoelectric, ferroelectric, and dielectric responses of ferroelectric materials. However, domain walls and strain field effects on thermal properties are unknown. We measured the thermal conductance from 100–400K of epitaxially grown BiFeO3 thin films with different domain variants, each separated primarily by 71 deg. domain walls. We determined the Kapitza conductance across the domain walls, which is driven by the strain field induced by the domain variants. This domain wall Kapitza conductance is lower than the Kapitza conductance associated with grain boundaries in all previously measured materials.

This work was partially funded  from the AFOSR Young Investigator Program (FA9550-13-1-0067).