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Bed Poudel is the first-listed author of High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys by Bed Poudel and others. The work connects nanostructure and phonon scattering at grain boundaries and defects to reduced thermal conductivity. This provides an experimental example of improving performance measured by the thermoelectric figure of merit by changing the microstructure of a bulk material.^[ref]

A nanostructure has structural features on the nanoscale. The relevant dimension may be the thickness of a thin film, the diameter of a nanowire, or the overall size of a nanoparticle. A material can therefore be macroscopically large while containing nanostructures internally.

The geometry matters because it changes the relative importance of surfaces, the distances over which charge carriers move, and sometimes the allowed quantum states. A thin film and a nanoparticle made from the same chemical material need not have the same properties: their quantum confinement dimensions and exposed surface areas differ. Characterizing a nanostructure requires specifying which dimensions are small, its shape and its chemical chemical composition, rather than reporting a single size alone.^[ref]

Nanotechnology studies and controls matter whose important dimensions are on the nanoscale, conventionally about $1$–$100$ nanometres. A nanometre is $10^{-9}$ metres. The scientific interest comes from changes in behaviour at these dimensions, including the increasing role of surfaces and, in suitable systems, quantum confinement.^[ref]

For example, subdividing a fixed volume into smaller nanoparticles increases the exposed surface area, changing how much material can participate in a surface reaction. Nanostructures can also alter electrical conductivity, interaction with light and mechanical properties by controlling geometry rather than changing only chemical chemical composition. Useful nanotechnology therefore combines fabrication with measurements of structure and properties, such as electron microscopy or atomic force microscopy.^[ref]

Use a shaped nickel particle or nanowire as both sacrificial template and reducing agent. gold grows where nickel is consumed, allowing gold-coated particles, porous shells and, with suitable removal of the remaining nickel, hollow gold nanostructures. The original template controls the overall shape; the balance of dissolution, deposition and diffusion controls wall thickness and porosity.

A hollow product is not guaranteed simply by writing the reaction: deposition may seal a solid nickel core, whereas defects can maintain access to the interior and permit further replacement. Controlled composition and transport can give a progression from core–shell to porous or hollow structures. This is useful for high-surface-area electrodes, catalytic surfaces and plasmonic structures, while avoiding an electrical lead to every individual nanoparticle.