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Van der Pauw method
About: Van der Pauw method is a research topic. Over the lifetime, 1682 publications have been published within this topic receiving 25364 citations.
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TL;DR: In this article, quasi-free-standing monolayer and bilayer graphene is grown on homoepitaxial layers of 4H-SiC and the epilayers themselves are grown on the Si-face of nominally on-axis semi-insulating substrates using a conventional SiC hot-wall chemical vapor deposition reactor.
22 citations
TL;DR: The use of the synthesized TCO nanomaterials for thin film fabrication was finally demonstrated by deposition of a transparent, conductive film using a simple spin-coating process.
Abstract: A high-throughput optimization and subsequent scale-up methodology has been used for the synthesis of conductive tin-doped indium oxide (known as ITO) nanoparticles. ITO nanoparticles with up to 12 at % Sn were synthesized using a laboratory scale (15 g/hour by dry mass) continuous hydrothermal synthesis process, and the as-synthesized powders were characterized by powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy. Under standard synthetic conditions, either the cubic In2O3 phase, or a mixture of InO(OH) and In2O3 phases were observed in the as-synthesized materials. These materials were pressed into compacts and heat-treated in an inert atmosphere, and their electrical resistivities were then measured using the Van der Pauw method. Sn doping yielded resistivities of ∼10–2 Ω cm for most samples with the lowest resistivity of 6.0 × 10–3 Ω cm (exceptionally conductive for such pressed nanopowders) at a Sn concentration of 10 at...
22 citations
TL;DR: In this paper, the authors explored a novel approach to electrode preparation employing amorphous cathode materials and found that the local electronic conductivity in the amorphou cathode surface is enough to preserve its catalytic properties.
Abstract: Lowering the operating temperature of solid oxide fuel cell (SOFC) devices is one of the major challenges limiting the industrial breakthrough of this technology. In this study we explore a novel approach to electrode preparation employing amorphous cathode materials. La0.8Sr0.2CoO3−δ dense films have been deposited at different temperatures using pulsed laser deposition on silicon substrates. Depending on the deposition temperature, textured polycrystalline or amorphous films have been obtained. Isotope exchange depth profiling experiments reveal that the oxygen diffusion coefficient of the amorphous film increased more than four times with respect to the crystalline materials and was accompanied by an increase of the surface exchange coefficient. No differences in the surface chemical composition between amorphous and crystalline samples were observed. Remarkably, even if the electronic conductivities measured by the Van Der Pauw method indicate that the conductivity of the amorphous material was reduced, the overall catalytic properties of the cathode itself were not affected. This finding suggests that the rate limiting step is the oxygen mobility and that the local electronic conductivity in the amorphous cathode surface is enough to preserve its catalytic properties. Different cathode materials have also been tested to prove the more general applicability of the amorphous-cathode route.
22 citations
TL;DR: In this paper, the optical properties of a nearly stochastic single crystal of tantalum carbide were reported, where the authors measured the reflectance between 0.03 and 6.0 eV and ellipsometry measurements were made between 1.2 and 4.6 eV.
Abstract: Optical properties of a nearly stoichiometric single crystal of tantalum carbide are reported. Specular reflectance was measured between 0.03 and 6.0 eV, and ellipsometry measurements were made between 1.2 and 4.6 eV. The ellipsometry results were used to fix the value of the phase obtained from a Kramers-Kronig analysis of the reflectance over a finite energy interval, and optical functions were computed between 0 and 6 eV. The optical conductivity at zero photon energy agrees well with the electrical conductivity obtained from resistivity measurements made by the van der Pauw method. Intraband contributions to the optical properties are assessed in terms of both one-carrier and two-carrier models. Broad structure near 5 eV is interpreted as due to interband transitions between states near the square face of the Brillouin zone.
22 citations
TL;DR: In this paper, the authors used a combined EDTA-citrate complexing sol-gel method to synthesize a solid oxide fuel cell (PBSCN) with various proportions of nickel.
22 citations