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ZrCoSb1−xSnx (x = 0, 0.1, 0.2, 0.3, 0.35) half-Heusler (HH) samples were prepared by arc melting, ball milling and then hot-pressing. X-ray diffraction analysis results showed that all samples were crystallized in a HH phase. Thermoelectric (TE) properties of ZrCoSb1−xSnx were measured from room temperature (RT) to 973 K. The Seebeck coefficient changed from negative to positive after substituting Sb with Sn, indicating the occurrence of conduction type transformation in ZrCoSb-based HH compounds. At the same time, the Seebeck coefficient decreased with increasing Sn substitution, and the electrical conductivity increased obviously with Sn addition when x ≤ 0.3. The lattice thermal conductivity of Sn-substituted samples was reduced dramatically because of the stronger phonon scattering by the strain field fluctuation induced by Sn replacement of Sb. Finally, as a result of the Sn substitution, a peak ZT of 0.52 was reached at 973 K in the ZrCoSb0.7Sn0.3 sample.

Nanostructured tin oxide has drawn extensive attention from researchers as a semiconductor, owing to its unique physicochemical properties. In this study, a mixed-valence tin oxide, hierarchical flower-like Sn3O4 self-assembled with numerous nanosheets was successfully synthesized using a simple hydrothermal process. The structure, morphology, and specific surface area were characterized using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an automatic surface area analyzer, respectively. The obtained Sn3O4 products had hierarchical nanostructures and uniform flower-like morphology. The diameter of this flower ranged from 300 nm to 2.6 μm. The flower-like Sn3O4 was self-assembled by nanosheets with a thickness of 8 ∼25 nm. By controlling the temperature of hydrothermal reaction and the concentration of surfactant, the as-synthesized hierarchical flower-like Sn3O4 (Sn3O4−25SC) can obtain the largest specific surface area of approximately 66 m2∙g−1, and thus exhibits excellent photocatalytic activity while degrading the methylene blue (MB) aqueous solution under UV light irradiation. Results show that the degradation rate of dye MB can reach 97% within 60 min. Moreover, a possible growth mechanism of the flower-like architectures was proposed. Sodium citrate promotes the growth of Sn3O4 nanosheets and accelerates the self-assembling of nanosheets into flower-like architecture.

Part of a float zone Si wafer was given a prolonged anneal at 960°C. Au was then diffused into samples of the annealed and unannealed portions of the wafer for various periods of time. Au concentration was inferred from spreading resistance measurements. We find that the crystal which was annealed before deposition of Au produced a different Au accumulation as a function of time than the as-received crystal. Further, the Au concentration at the center of the wafer does not follow the previously reported t 1/2 behavior ; it follows a curve that exhibits an inflection. We believe these results are best interpreted in terms of vacancy clusters retained in the Si during the original crystal growth.

Many recent discussions of surface treatment effects on atomic diffusion in Si have explained these largely in terms of effects attributed to Si self interstitials. However, we have shown by our straight forward Monte Carlo (VIDSIM) simulation of diffusion of Au into Si according to the “kick-out” mechanism of Seeger that this mechanism is in fact completely incapable of explaining the two-sided, “U shaped” profile of substitutional Au which results from a one sided in-diffusion of Au. We have shown that if Auinterstitials can displace Si at any appreciable rate, then the Au substitutional profile must decrease monotonically from source side to far side. We noted that this is strong evidence that Si self interstitials play no role in thermal processes in Si. Here we show that the surface treatment effects often attributed to Si self interstitials can be naturally explained without them.

After Au diffusion, carrier concentration profiles in low O (float zoned), lightly doped, p‐type Si were found to be a function of heat treatment received by the Si crystal prior to Au deposition. We interpret anomolous carrier concentration profiles in terms of vacancy diffusion and clusters of excess vacancies retained from the crystal growth processing.