Papers by Keyword: Flame Synthesis

Abstract: A premixed flame burner system was utilised to synthesise carbon nanotubes (CNTs). The morphologies of highly-graphitic carbon nanotubes were characterised by using transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The XRD analysis shows the spectrum of a typical CNT, while TEM imaging shows the physical structure of the carbon nanotubes. CNTs were grown effectively on a Ni-contained substrate in an elevated temperature environment. The flame synthesised CNTs were of high crystalline, multi-wall structure, and contained relatively less impurities and amorphous carbon. The CNT intershell spacing values quantified using TEM and XRD are 0.317 nm and 0.344 nm respectively. CNTs produced from flame synthesis are based on the tip-growth model and vapor-liquid-solid (VLS) mechanism.

Abstract: Mono-dispersed Nickel oxide nanoparticles were directly formed on the carbon fibers through a facile in situ flame synthesis method. High magnification SEM and TEM study revealed that the nickel oxide nanoparticles have a polyhedral structure and are uniformly distributed on the surface of carbon fibers. The concentration effect of the precursor used on the growth of polyhedral nickel oxide nanoparticles on carbon fibers has been studied.

Abstract: The present work is devoted to studying photoelectrical properties of the solar cells covered with nickel oxide nanoparticles synthesized in counter flow propane flame. In the given case, the nanoparticles of oxides play the role of quantum points on the surface of the solar cells and promotes effective absorption of light energy. The applying of silicon solar cells of nickel oxide nanoparticles to the surface caused the increase of output open circuit voltage of 4-7 %, the increase of short - circuit current of 20 - 28 %, that in total caused the increase of efficiency of the solar cells by 2-3%.

Abstract: Catalysts play a critical role in the synthesis of carbon nanotubes. In this paper, we design a series of experiments to explore the impact of contents of Mo on the products. Analysis show, when the molar ratio of Fe: Mo: Al is 1: 0.2: 16, the carbon nanotubes show the best yields and quality.

Abstract: We introduce a case study of “high sphericity” and “high uniformity” generated through flame synthesis. Recently, cosmetics need to solve 1) UV-protective effect, 2) transparence, and 3) smooth-textured touch. However, the best recipe and usable evaluation methods are not established. This research is a result combined with a theoretical approach of flame formation process, and a strategic regional alliance of the “AIST” grant venture. A new manufacturing and evaluation method has been commercialized in the forms of a highly original cosmetics and a new evaluation device.

Abstract: The present chapter deals with the difficult task of giving a brief survey of the synthetic routes employed to prepare materials with characteristic features on the nanometer scale. Definitions and general concepts regarding nanostructured and nanometer-sized materials are shortly tackled in the introductory part, which is followed by an overview of the most important approaches developed to synthesize such materials. No attempt is made to create a comprehensive and detailed synopsis of the experimental methods currently available. Rather, attention is focused on a selected number of general methodologies, the choice of which can be usually motivated by a mix of historical perspective, scientific significance and technological potential. So-called “top-down” approaches are discussed first, whereas the second part of the chapter is devoted to “bottom-up” ones. The former group includes mechanical processing, melt quenching, and de-vitrification methods. Sonochemistry, pulsed laser ablation, wet chemical synthesis, sol-gel processing, microwave processing, spray pyrolysis, flame synthesis, inert gas condensation, vapor deposition, and vapor-liquid-solid growth form instead the latter group.

Abstract: The work reports on the preparation and properties of binary alumina-rare-earth oxide glass microspheres with high contents of aluminium oxide. Because Al2O3 is not a typical glass former, preparation of these glasses in bulk is difficult due to high melting temperatures and high tendency to crystallisation, which requires high cooling rates. One of the possibilities is preparation of glass microspheres by flame synthesis and rapid quenching of microspheres by spraying them with water. Microspheres with dimensions ~10 µm and with various compositions from the systems RE2O3-Al2O3 (RE = Y, Yb, La) have been prepared with the use of an in-house built equipment. The prepared microspheres have been characterised by SEM-EDX, IR, XRD and DTA.

Abstract: Even though activated carbon fibers (ACF) have been attractive due to high specific surface area and uniform micropore structure, there are only a few reports about the photocatalyst immobilization on ACF or their photodegradation behavior for removal of organic pollutants. In this study, ACF were selected as adsorptive support for photocatalyst immobilization. As photocatalysts, TiO2 nanoparticles were synthesized by using a N2-diluted and oxygen-enriched co-flow hydrogen diffusion flame. The visible flame length of 150mm was obtained by direct photographs. Flame temperature was measured by rapid insertion measurement technique with a R-type (Pt/Pt-13%Rd) thermocouple which was in wire shape (127μm diameter). TiO2 particles were sampled by using a high temperature particle sampler and then were coated on ACF filters. The sampling was carried out at 70mm and 110mm above the burner. The structure of TiO2 particles was analyzed by XRD. TiO2 coated ACF filters were characterized by FESEM-EDX and BET analyses. TiO2 particles on ACF filters were found to be agglomerated particles and the size of primary particles was approximately 50nm. The structure of TiO2 particle was anatase-phase crystalline structure. The specific surface area of TiO2 coated ACF filter was enhanced to be 1700~1860m2/g, depending on the sampling location, and the pores were micropores, regardless of the sampling location.