Extreme Thermal Test Platform
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We have developed a platform for studying the atomic scale properties of materials at thermal extremes, reaching temperatures in excess of 4,000K. We find that carbon nanotubes are thermally stable to 3,200K, exceeding the breakdown temperature of the other common allotropes of carbon, graphite and diamond. We also find that the electrical and thermal conductivities of nanotubes remain high from room temperature up to high temperature failure, implying far reaching applications in extreme conditions.
This test platform allows us to observe the evolution of a single nanotube in real time inside a high resolution transmission electron microscope. The images at right show a nanotube decorated with gold nanoparticles that act as local temperature sensors. As we drive increasing current through the nanotube, these nano-thermometers melt and evaporate to reveal the temperature profile of the system. Watch a video of the process.
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As a further application, we use these high temperature carbon nanotube heaters to study the electrical conductivity, thermal conductivity, and thermal stability (including melting point and sublimation point) of individual nanoscale objects. We perform real-time atomic resolution imaging of the nano-objects as they evolve in time/temperature. We can literally see how the atoms of the material shift and how the material falls apart, and know exactly at what temperature what happens, and determine the thermal/electrical transport properties of the object for each configuration.
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Click the image to the right to view a rendition of small gold nanoparticles melting on a nanotube surface. The melting temperature of particles in this size scale (few nanometers) varies strongly with particle diameter. The nanoscale test platform is used to measure the this effect. As we increase the voltage applied to the nanotube, the temperature increases, allowing larger and larger particles to melt.
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Click here to see my other research projects!
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