Selective growth of amorphous silica nanowires on a silicon wafer deposited with Pt thin film is reported. The mechanism of nanowire growth has been established to follow the vapour liquid solid (VLS) model via the PtSi phase acting as the catalyst. Nanowires grow with diameters ranging from 50 to 500 nm. These bottom-up grown nanowires exhibit photoluminescence with a stable emission of blue light at 430 nm under excitation. The effect of varying the seed layer thickness (Pt film) from 2 to 100 nm has been studied. It is observed that, above 10 nm thickness, a continuous layer of Pt(2)Si re-solidifies on the surface, inhibiting the growth of nanowires. The selectivity to the Pt thickness has been exploited to create regions of nanowires connected to conducting silicide (Pt(2)Si) simultaneously in a single furnace treatment. This novel approach has opened the gateways for realizing hybrid interconnects in silicon for various nano-optical applications such as the localization of light, low-dimensional waveguides for functional microphotonics, scanning near-field microscopy, and nanoantennae.

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Graphitic carbon nanofibers are catalytically grown on commercial carbon felt microfibers, and carbothermal treatment then produces interfacial silicon carbide phase rendering the supported nanofibers mechanically robust and chemically stable. This pliable 3‐dimensional porous nanocomposite material reveals a hierarchical structure mimicking lotus leaves and depicts superhydrophobicity and reversible wettability.

SUMMARYMagnetocaloric cooling is an alternative, high-efficiency cooling technology. In this paper, we present the design and fabrication of a micromachined magnetocaloric cooler and demonstrate its ability to work in a small magnetic field ð51:2 TÞ with a cooling test. The cooler was built by fabricating Si microfluidic channels, and it was integrated with a Gd 5 ðSi 2 Ge 2 Þ magnetocaloric refrigeration element. The magnetic properties of the Gd 5 ðSi 2 Ge 2 Þ material were characterized to calculate the magnetic entropy change at different ambient temperatures. Three different methods to integrate the channel layer and the magnetocaloric element were evaluated to test sealing and cooling performance. The cooling tests were performed by providing a magnetic field using an electromagnet. A test jig was constructed between the poles of an electromagnet to maintain a steady temperature during the test. Cooling tests were performed on the magnetocaloric element at ambient temperatures ranging from 258 to 280 K using a magnetic field of 1.2 T. Experimental results showed a maximum temperature change of 7 K on the magnetocaloric element alone at an ambient temperature of 258 K. Cooling tests of the fully integrated coolers were also performed. A solution of anti-freeze fluid (propylene glycol) and water was used as the coolant. The temperature of the working fluid decreased by 4.6 and 9 K for the glass and Si intermediate layers, respectively, confirming that the thermal conductivity of the materials is also an important factor in cooler performance.

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The synthesis, characterization, and electrical measurements of graphitic carbon nanofiber (GCNF)/ carbon paper composite materials are reported. GCNF/carbon paper composites having relatively weak GCNF/carbon paper and GCNF/SiO 2 /carbon paper interfacial binding are prepared by growing carbon nanofibers directly from growth catalyst nanoparticles distributed throughout the carbon paper support. Carbothermal reduction of GCNF/SiO 2 /carbon paper composites effectively "spot welds" carbon nanofibers to carbon paper fibers affording mechanically robust GCNF/SiC/carbon paper composite materials. Characterization methods include scanning electron microscopic imaging, chemical composition and elemental mapping by energy-dispersive X-ray spectroscopy, X-ray diffraction and Raman spectroscopy for phase identification, BET surface-area analysis, and measurement of in-plane and contact electrical resistance. Plots of the pressure dependence of the contact resistance of GCNF/carbon paper and GCNF/ SiC/carbon paper composites fall between those of commercial plain carbon paper and wet-proofed carbon paper with the GCNF/SiC/carbon paper composite having a contact resistance similar to that of plain carbon paper. A method for instilling a nano/microscale hierarchical architecture to carbon paper without incurring significant increase of contact resistance is reported.

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