Ag defects in Σ3 grain boundary of SiC were analyzed to test the hypothesis that Ag release from tristructural isotropic (TRISO) fuel particles can occur through grain boundary diffusion. Although Σ3 grain boundarie...
Ag defects in Σ3 grain boundary of SiC were analyzed to test the hypothesis that Ag release from tristructural isotropic (TRISO) fuel particles can occur through grain boundary diffusion. Although Σ3 grain boundaries cannot provide a connected path through the crystal, they are studied here to provide guidance for overall trends in grain boundary vs bulk Ag transport. Formation energies of Ag defects are found to be 2–4 eV lower in the grain boundaries than in the bulk, indicating a strong tendency for Ag to segregate to the grain boundaries. Diffusion of Ag along Σ3 was found to be dramatically faster than through the bulk. At 1600∘C, which is a temperature relevant for TRISO accident conditions, Ag diffusion coefficients are predicted to be 3.7×10−18 m2/s and 3.9×10−29 m2/s in the Σ3 grain boundary and bulk, respectively. While at this temperature Σ3 diffusion is still two orders of magnitude slower than diffusion estimated from integral release measurements, the values are close enough to suggest that grain boundary diffusion is a plausible mechanism for release of Ag from intact SiC coatings. The remaining discrepancies in the diffusion coefficients could be possibly bridged by considering high-energy grain boundaries, which are expected to have diffusivity faster than Σ3 and which provide a connected percolating path through polycrystalline SiC.
Metal organic chemical vapor deposition (MOCVD) tools are integral to many technologies, including the growth of high-efficiency multijunction III-V solar cells. Veeco MOCVD has recently developed new tool designs tha...
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We investigated postannealing temperature dependence of the structural and magnetic properties of Co2Ti0.5Mn0.5Al and Co2Ti0.5Mn0.5Si films. It was observed that the Co2Ti0.5Mn0.5Al film formed an ordered L2 1 structu...
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We used a “graphene-like” mechanical exfoliation to obtain atomically thin films of TiTe2. The building blocks of titanium ditelluride are atomic tri-layers separated by the van der Waals gaps. The exfoliation proce...
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We used a “graphene-like” mechanical exfoliation to obtain atomically thin films of TiTe2. The building blocks of titanium ditelluride are atomic tri-layers separated by the van der Waals gaps. The exfoliation procedure allows one to obtain the few-atom-thick films with strong confinement of charge carriers and phonons. We have verified the crystallinity of the exfoliated films and fabricated the back-gated field-effect devices. The current – voltage characteristics of the TiTe2 devices revealed strong non-linearity, which suggests the charge-density wave effects. The obtained results are important for the proposed application of TiTe2 for the charge-density wave devices and thermoelectric energy conversion.
We investigated the data transmission performance of indium antimonide (InSb) nanowires (NWs) synthesized on InSb (100) substrate using chemical vapor deposition (CVD) having diameters of 20 nm and below. The results ...
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We investigated the electrical properties and transmission line performance of indium antimonide nanowires. The results indicate that the of nanowires suffer from low mobility values on the order of 10-to-15 cm2V -1s-...
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The space charge region width of the Schottky barrier that forms on the interface between aluminum and organic semiconductor polymer of bulk-heterojunction organic photodiodes has been investigated according to revers...
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