Research

Below are images. Click on the image to see a larger view.

Nanostructural Bulk Chalcogenides

TEM image

High resolution TEM image showing spinodally decomposed regions in PbTe-16%PbS.

TEM image

TEM images showing dispersed nanoparticles in samples of: (A) PbTe-Sb(2%) (B) PbTe-Sb(4%) (C) PbTe-Sb(8%) and (D) PbTe-Sb(16%).

A pulsed-laser enhanced 3-D LEAP tomograph involves replacing electric pulses with picosecond laser pulses, indicated by incident red wave in left-hand figure. Simulation of the electric field (E) at a tip caused by the E-field of the laser pulse, see right-hand figure. (Prof. Tamar Seideman)

Computational Approaches

First-principles KMC calculated evolution of Cu precipitates in Al-Cu (2% Cu). For visual clarity, only Cu atoms are shown. The simulation cell contains more than 250,000 atoms.

Self Assembled Nanostructures

TEM image

Transmission electron micrographs of lead chalcogenide nanoparticles and low-dimensional networks (aerogels): (a) highly crystalline ca. 5 nm spherical nanoparticles of PbSe with lattice fringes readily apparent; the inset shows the electron diffraction pattern, which can be indexed to PbSe. (b) cube-shaped particles of PbSe; the inset shows a high resolution image with lattice fringes. (c) PbTe nanoparticles; lattice fringes are apparent in the high resolution image (inset); (d) PbSe aerogel prepared from (a). (e) PbSe aerogel prepared from particles in (b); the inset shows an expanded region revealing the hierarchical nature of the assembly. (f) PbTe aerogels .

Thermoelectric Devices & Systems

Aerogel encapsulation enabling integration of thermoelectric elements directly into exhaust stream. Convective gas heat transfer is significantly impeded by nanoscopic pores and radiative heat transport is reduced by the addition of opacifying agents.