Thallium Telluride film

Planar SEM image of thin film of TlTe grown at –250mV vs Ag/AgCl (3M NaCl)

Thallium Telluride nanowire array

Cross-section back-scattered SEM image of Tl5Te3 nanowire array showing overgrowth. Light contrast shows nanowires in and overgrowth on porous aluminum oxide film.

Lead Telluride films

Morphology of PbTe films under differing growth potentials.

Thermoelectic couple

Optical image of thermoelectric couple.

Lead telluride nanowire leg

SEM image of lead telluride nanowire leg. Dark contrast shows nanowire array.

Nanowire array

Cross section backscattered SEM of nanowire array of Lead Telluride. Light contrast shows nano wires in dark contrast porous aluminum oxide film.

Contacting nanowires

Electrochemical Ni on PbTe nanowires.

Contacting nanowires

PbTe/Ni nanowire contacting method

Contacting nanowires

PbTe/Ni nanowire contacting method

Contacting nanowires

Immersion Au on PbTe nanowires. Bright contrast spheres on wires is gold.

Filled porous aluminum oxide template

Optical image of polyaniline filled PAA template. The green coloration is indicitive of emeraldine - an electrically conductive form of polyaniline.

Polyaniline nanotubes

Cross-section SEM image of polyaniline nanotubes

Polyaniline nanotubes

Cross-section SEM image of polyaniline nanotubes

Polyaniline nanotubes

Cross-section SEM image of polyaniline nanotubes

Polyaniline nanotubes

Cross-section SEM image of polyaniline nanotubes

Measurement of a wire bundle

Probe tips being used to measure resistance of a spot welded bismuth telluride wire bundle at the CINT facility in Albuquerque

Electrodeposited tellurium

Tellurium growth, dark, on the platinum backing layer, white, of a template that was not properly insulated during deposition

Moving a nanowire

Manipulation of a single bismuth telluride wire at the CINT facility in Albuquerque

Vapor-deposited tellurium

Crack in a single crystalline needle of pure tellurium

Nanowire fragments

Fragments of broken bismuth telluride nanowires seen after etching a sonicated Whatman® template

Electrodepostied and chemically converted zinc oxide

Zinc oxide growth on the surface of a porous alumina template

Etched porous alumina template with overgrowth

An etched alumina template. The hemispheres are overgrowth which have protected the alumina below them, resulting in unetched islands

Electrodeposited bismuth telluride

Cross section of overgrown bismuth telluride. The overgrowth and nanowires show the brightest contrast, while the template itself is a light grey

Electrodeposited tellurium

Collection of images showing uniform wire growth of tellurium across a full cross section of an array. The bright areas have wires, while the darker areas are unfilled.

Etched porous aluminum oxide

Cracks running through a full template which has been etched. The bright contrast areas are from the platinum backing layer.

Etched porous aluminum oxide

Top down view of a partially etched template. The grey areas are the unetched template, while the dark areas are unfilled.

Electrochemical deposition of CuxS thin film

SEM image of CuxS thin film deposited electrochemically on a platinum electrode. Light contrast is the platinum electrode. The dark and medium contrasts are CuxS of various thickness and composition.

Electrochemically Deposited CuxS with Crystals

SEM image of CuxS thin film deposited electrochemically on an aluminum electrode. Dark contrast is aluminum electrode. Lighter areas are CuxS and the crystals that formed are sulfur.

The Stacy group is involved in the development of new synthetic routes that lead to the discovery of materials for emerging technologies. X-ray diffraction, electron microscopy, and electron microprobe are used to examine the structure and composition of new materials that are obtained. With electron microscopy, detailed information on the nanoscale is gathered. A range of bulk and surface properties are measured, including electrical and thermal transport, optical absorbance, and surface activity. On the basis of insights gained as to the relationship between structure and properties, the synthetic conditions are adjusted in order to tailor materials for specific applications.

With new abilities to control materials on the nanoscale and to create composites that are ordered arrays of two types of materials, there is much room for discovery. As new understanding about how properties vary with nanoscale dimensions are garnered, this knowledge can be put to use in enhancing properties for specific applications. The growth of understanding in nanoscience provides exciting new possibilities for the development of thermoelectric materials with enhanced efficiencies, inexpensive earth abundant photovoltaic cells, and materials with organized geometries for the studies of super-hydrophobic surfaces. We are working on the synthesis and characterization of materials with these qualities.