First-principles studies on the phase stability of thermoelectric materials.
One method of improving the efficiency of thermoelectric materials is by decreasing the lattice thermal conductivity of the material. This can be accomplished by adding nanoscale particles to the material which disrupt phonon heat transport but not electron motion. In systems like PbS-PbTe which have a solid-solid miscibility gap, particles can be precipitated from the bulk by two mechanisms: nucleation and growth or spinodal decomposition. These precipitates can either be coherent with the matrix they came from, or incoherent with their own lattice parameters and orientations. Since coherent precipitates should allow better conduction of electrons while still scattering phonons, knowing how coherent precipitates form in these systems is important. We are using first principles Density Functional Theory (DFT) to study the thermodynamics of incoherent and coherent phase separation in IV-VI rocksalt semiconductor systems like PbS-PbTe.
Jeff graduated from Missouri State University in 2009 with a B.S. in Physics and Mathematics.