Through the rolled‐up glass: We demonstrate an alkali‐free glass (• in figure) with high permittivity, low dielectric loss, high energy density, and potential self‐healing capabilities that significantly performs better for high temperature–high power capacitor applications prepared through a standard roll‐to‐roll process than currently used polymer films (shown for comparison).
Thermal characterization of conducting polymers is important in understanding transport phenomena in energy conversion and flexible electronics devices. We present an experimental technique to determine the in-plane thermal conductivity and the thermal contact resistance of thin films on substrates simultaneously. For 20 nm thick polyaniline films on SiO2 substrate, the respective values were measured to be 0.0406 W/m K and 0.806 K m2/W. We also observed thickness dependence of in-plane thermal conductivity, which suggests that heat transfer is governed by phonon-boundary scattering when the film thickness is close to the mean free path.
The amorphous to crystalline phase transformation process is typically known to take place at very high temperatures and facilitated by very high compressive stresses. In this study, we demonstrate crystallization of amorphous ultra-thin platinum films at room temperature under tensile stresses. Using a micro-electro-mechanical device, we applied up to 3% uniaxial tensile strain in 3-5 nm thick focused ion beam deposited platinum films supported by another 3-5 nm thick amorphous carbon film. The experiments were performed in situ inside a transmission electron microscope to acquire the bright field and selected area diffraction patterns. The platinum films were observed to crystallize irreversibly from an amorphous phase to face-centered cubic nanocrystals with average grain size of about 10 nm. Measurement of crystal spacing from electron diffraction patterns confirms large tensile residual stress in the platinum specimens. We propose that addition of the externally applied stress provides the activation energy needed to nucleate crystallization, while subsequent grain growth takes place through enhanced atomic and vacancy diffusion as an energetically favorable route towards stress relaxation at the nanoscale.
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