Production of Nanopowders

Production of nanopowders can be carried out by vapor-phase reactions. These reactions are more versatile, in the sense that we can produce both oxide and nonoxide powders. The powder produced is of high purity, it contains discrete particles, and its size distribution is narrow. Since the process is expensive, it is not used for the commercial production of powders. 

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An atmospheric inductive plasma torch offers quite significant advantages for the production of nanopowders for catalysts ... 

Plasma-chemical processes (7-94) can be applied not only for production of nanopowders of carbides bnt also for deposition of thin carbide films. Specifically, we mention here the deposition of a boron carbide film based on the gas-phase process similar to (7-95) but with an excess of hydrogen ... 

Nadaraia L, Jalabadze N, Chedia R, Khundadze L (2013) Production of nanopowder and bulk aluminate ceramic scintillators. Ceram Int 39 2207-2214... 

Widely used methods in the synthesis of silica nanoparticles are the sol-gel process and flame synthesis [5]. The latter is an effective synthetic route to continuously produce extremely pure nanoparticles, but in many cases the final products are agglomerated or show low reactive surfaces that make them difficult to functionalize. Nevertheless, flame synthesis is a prominent method to commercially produce silica nanopartides in powder form [6]. It is being used since decades for the production of the so-called fumed siUca, which is a filler in many applications, for example, in the pharmaceutical or polymeric business [7]. The extension of this preparation route is the so-called flame spray pyrolysis that has expanded in the last two decades to many other material compositions and is a promising rapid technique for the production of nanopowders [8]. 

Of significant interest is the use of nanodiamond powders for strengthening polymer materials. Nanopowders of oxides obtained from clay are used for these purposes at present. In commercial production of nanopowders by detonation the cost of nanodiamond powders and nanooxides obtained from clay becomes commensurate. That is, there are almost no obstacles of economic character for broad introduction of diamond nanopowders. 

Grain growth of zinc oxide occurs at much lower temperatures than in titania, so that production of fairly crystalline ZnO nanopowders needs special precautions. The thermal decomposition of freeze-dried Zn(N03)2 at 260 to 270°C results in the formation of poorly crystalline, but coarse-grained ZnO powders. " At the same time, insulation of ZnO particles in the inert NaCl matrix by the method described before - led to no change in the size of the ZnO particles. The ZnO particles were obtained from freeze-dried precipitate of zinc hydroxide of 15 to 20 nm, and this size was maintained at least up to 600°C. "... 

To conclude, the LuaOstEu (1 at. %) nanopowders were prepared by co-precipitation method using ammonium hydracarbonate as precipitant. It was shown that Lu203 Eu low-agglomerated monodispersed spherical powders with specific surface area of S=14 m /g can be obtained by precursor calcination at T=1000 °C. It was determined, that the resultant powders can be used for production of Lu203 Eu translucent ceramics with average crystalline size of 18-20 mkm, nearly full density (99 %), and in-line transmittance coefficient up to 20 % even if the uniaxial pressure method is used for nanopowder compaction. 

Other Processes of Plasma Production of Nanoparticles Synthesis of Aluminum Nanopowder and Luminescent Silicon Quantum Dots... 

N.G. Glumac, Y.J. Chen, G. Skandan, B. Kear, Scalable high-rate production of non-agglomerated nanopowders in low pressure flames . Materials Letters, 34, 148-153, (1998). 

In this chapter, we summarize the experimental results obtained by Latvian scientists in production of AlN ceramics with use of nanopowders as initial sintering materials and study of its dielectric and luminescence properties, as well as consider novel areas of application for this prospective material. 

The plasma chemical method is relatively often used now for preparing many nanopowders for production of refractory compounds (nitrides, oxides, carboni-trides, and their compositions) [6]. The process of preparing aluminum nitride nanopowder by this technique is based on evaporation of aluminum in high temperature nitrogen flow, following chemical interaction, and subsequent condensation of reaction product. It means that this process could be considered as a kind of combustion synthesis. 

Torri, C. Lesci, I.G. Fabbri, D. Analytical study on the production of a hydroxylactone from catalytic pyrolysis of carbohydrates with nanopowder aluminium titanate. J. Anal. Appl. Pyrol. 2009, 84, 25-30. 

The chemical reduction of transition metal salts and oxides allows the production of X-ray amorphous nanopowders (I) or colloidal metals protected by THF (II) or NR4+- or PR4+-groups (III). 

Gas-phase methods are widely used for the industrial production of the metal oxide nanopowders with diverse particle sizes that are often used as feedstocks in the preparation of ceramics. The stabilization of such powders has provend difficult task, however, and many of today s in vivo applications of nanomaterials rely on solution-based methods, based on much better possibilities of functionalization and manipulation. Comminution has also begun to be accepted for the production of nanoscale powders, although its use for high-purity zirconia nanomaterials, as required for biomedical use, is severely hampered by the extreme hardness of Zr02-... 

High-Rate Production of High-Purity, Nonagglomerated Oxide Nanopowders in Flames... 

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