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Entangled networks of carbon nanofibers are characterized both mechanically and electrically. Results for both tensile and compressive loadings of the entangled networks are presented for various densities. Mechanically, the nanofiber ensembles follow the micromechanical model originally proposed by van Wyk nearly 70 years ago. Interpretations are given on the mechanisms occurring during loading and unloading of the carbon nanofiber components. [ABSTRACT FROM AUTHOR]

The design, fabrication and characterization of a recently developed test platform for the characterization of nanoscale properties of thin films are presented. Platforms are comprised of a microfabricated cascaded thermal actuator system and test specimen. The cascaded thermal actuator system is capable of providing tens of microns of displacement and tens of milli-Newton forces simultaneously while applying a relatively low temperature gradient across the test specimen. The dimensions of the platform make its use possible in both the scanning/transmission electron microscope environments and on a probe station under an optical microscope. Digital image correlation was used to obtain similar accuracy (~10 nm) for displacement measurements in both a SEM and under an optical microscope. Proof of concept experiments were performed on freestanding 250 nm thick Pt thin films. [ABSTRACT FROM AUTHOR]

The Suspended Thermoreflectance (STR) technique is described in this paper. This optoelectronic measurement tool performs thermal characterization of freestanding micro-/nanoscale materials. STR performs thermal mapping at the submicron level and produces unconstrained thermal conductivity unlike other optical measurement techniques where independent conductivity measurement is not possible due to their reliance on heat capacity. STR works by changing the temperature of a material and collecting the associated change in light reflection from multiple points on the sample surface. Reflection is a function of the material being tested, the wavelength of the probe light, geometry, and the composition of the specimen for transparent and quasi-transparent materials. In this article, Si μ-cantilevers are studied. In addition, a thermal analytical model is developed and incorporated with optical equations to characterize the conductivity of the Si μ-cantilevers. The analytical model is compared with a finite element model to check its applicability in the STR experiment and data analysis. To validate the technique, the thermal conductivity of 2 and 3 µm thick Si μ-cantilevers was determined using STR at a temperature range of 20-350 K and compared to simulations using the equation of phonon radiative transfer and literature values., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)