ABSTRACT
According to the innovative design concept of omnidirectional quasi-order hetero-nanocomposites proposed for potentially realizing high thermoelectric performance, a series of superarchitectures consisting of longitudinally periodic diamond-like carbon (DLC) interlayers in latitudinally well-aligned Bi-Sb-Te (BST)-based nanostructures were successfully demonstrated for the first time using dual-beam pulsed laser deposition. This work confirmed that the periodic appearance of DLC is a practical approach to instantly resetting the BST deposition into another new crystal growth cycle. The optimized Seebeck coefficient of â¼500 µV K-1 and the corresponding power factor of â¼40 µW cm-1 K-2 achieved are comparable to or higher than the reported values for BST or BST-based nanocomposites, which evidently originated from the periodically added DLC, as clarified in the Pisarenko plot. In addition, the DLC additives effectively reduce the thermal transport as qualitatively evidenced by micro-Raman characterizations.
ABSTRACT
We describe an innovative interfacial design concept and nanostructuring of novel BixSb2-xTe3 (BST) nanoassembled films comprising unique air-solid interfaces from micro-scaled open gaps to isolated sealed mesopores, and high-quality solid-solid ones including the coherent grain boundaries and specific twins, utilizing pulsed laser deposition (PLD), for potentially activating multiple thermoelectric enhancing mechanisms. The unusual mesopore embedded BST films exhibit the highest power factor of â¼33 µW cm-1 K-2, which is comparable to or higher than the previously reported values for BST, and the corresponding relatively low thermal diffusivity in contrast to that for dense pore-less BST films evidently reveals the crucial role of the three-dimensionally and densely arranged air-solid interfaces in significantly arising the phonon scattering.
ABSTRACT
We describe an innovative concept and facile approach in fabricating laterally assembled Ga2Te3/Te binary nanocomposite films, which comprise two-dimensional quasi-periodic Ga2Te3 nanoassemblies surrounded by interlocking highly-conductive Te single crystals for comprehensively establishing subnano- to micro-scaled multi-style versatile interfaces. The distinct Ga2Te3/Te nanocomposite film exhibits a power factor that is about 60 times higher than the reported conventional Ga2Te3 and Te materials, mainly due to the 2- to 3-order improved electrical conductivity and the comparable Seebeck coefficient.
ABSTRACT
A new method for the fabrication of periodic CNT arrays was developed in this study, which involves the use of the inverse nano-sphere lithography (INSL) process. Mo of a honeycomb pattern, acting as a catalyst-poisoning layer, was produced by the nano-sphere lithography (NSL) process; the Mo poisoned the catalyst and prevented CNT growth where deposited, and as a result, a periodic CNT pattern was obtained. Using this method, the uniformity of the CNT array can be improved by preventing the negative effect of arrangement defects in self-assembled monolayers. The size and the period of the CNT array can be adjusted by careful selection of the polystyrene (PS) sphere diameter. X-ray photoelectron spectroscope (XPS) analysis revealed that the Co catalyst was ineffective on the areas of Mo deposition due to the diffusion of Co into the Mo layer.
Subject(s)
Nanotechnology/methods , Nanotubes, Carbon/chemistry , Catalysis , Cobalt/chemistry , Microscopy, Atomic Force , Microscopy, Electron, Scanning , Molybdenum/chemistry , Surface Properties , Titanium/chemistryABSTRACT
The unique heating property of microwave irradiation on carbon nanotubes (CNTs) was applied in fabrication of a new architecture of two-dimensional metallic nanobowl array on a thermoplastic substrate. Vertically aligned CNT film was grown on a metal coated polystyrene (PS) submicron sphere array and then transferred onto a polycarbonate (PC) substrate by microwave heating. The back diffracted light spectra of this structure were measured and discrepancies between the spectra and that predicted from a diffraction relationship were studied. It is suggested that the discrepancies were related to the shape and the refractive indices of the materials.
