Abstract
We developed a method to visualize heat conduction pathways with nanoscale spatial resolution using scanning transmission electron microscopy (STEM) and a nanothermocouple assembled in a transmission electron microscope (TEM). Through combining a scanning heat input under STEM with the nanothermocouple piezo-driven movements and its precise positioning, we entirely controlled a heat flow through a tiny TEM specimen. We were also able to construct two-dimensional nanoscale heat maps which visualize the heat pathways in a nanocomposite material, i.e. alumina nanofillers embedded into an epoxy matrix. The method possesses unprecedentedly high temperature and spatial resolutions which allows for its smart implementation into nanoscale studies of thermal flow propagation within novel thermoelectric conversion materials, thermal diodes, heat-sink materials, etc. Various phenomena associated with heat can be also simultaneously analyzed via combined and comprehensive thermal tests inside TEM while merging them with structural, mechanical, electrical, magnetic, and optoelectronic characterizations of a material down to the atomic scale.
Highlights
With respect to the primary energy sources, like oil, gas, and coal, that mankind consumes, only one third is effectively used, while two thirds are being lost in some form, of which the majority is waste heat
Thermo-electromotive force, as a function of temperature changes during noncontact nanoscale thermal scanning over the sample (under convergent electron beam irradiation in a scanning transmission electron microscopy (STEM) mode), is measured employing a nano-thermocouple fixed to the specimen
This method, namely, STEM-based thermal analytical microscopy (STAM), is able to obtain detailed information in the form of two-dimensional thermal distribution maps revealing heat conduction in the fillers embedded in a composite material and/or between them
Summary
With respect to the primary energy sources, like oil, gas, and coal, that mankind consumes, only one third is effectively used, while two thirds are being lost in some form, of which the majority is waste heat. Thermo-electromotive force, as a function of temperature changes during noncontact nanoscale thermal scanning over the sample (under convergent electron beam irradiation in a scanning transmission electron microscopy (STEM) mode), is measured employing a nano-thermocouple fixed to the specimen. This method, namely, STEM-based thermal analytical microscopy (STAM), is able to obtain detailed information in the form of two-dimensional thermal distribution maps revealing heat conduction in the fillers embedded in a composite material and/or between them. It was theoretically established that the TEM specimen of dimensions similar to ours would return to in a steady state within 10−6 s or less after electron beam irradiation [21]
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