Preparation nanosized powders

In the present work, intensity of ultramarine Raman spectra have been enhanced by the order of magnitude with solid nanosized Ag particles. Model samples have been prepared as powder mixtures of the pigment and silver particles without any compressing pretreatment. This makes the sample preparation process more easy in contrast to a more traditional way based on SERS-active film from colloidal solution of nanosized Ag particles. The technique does not require much sample material from art objects and preparation of aqueous suspension from a sample. Taking into consideration the low solubility of art pigments in water we propose the sensitive method of pigment identification in real art objeets. 

Chiorino, A. Ghiotti, G. Prinetto, F. Carotta, M. C. Gnani, D. Marinelli, G., Preparation and characterization of Sn02 and MoO -Sn()2 nanosized powders for thick film gas sensors, Sens. Actuators B 1999,58, 338-349... 

Preparation and characterisation of W0i/Sn02 nanosized powders for thick films gas sensors... 

As compared to materials produced by traditional ceramic technologies using micrometer-sized powders, ceramics prepared from nanosized powders usually have different characteristics a dense ceramic with a submicron stracture is synthesized from nanopowders at relatively low temperatures (1100-1300 °C) and has a higher strength and a larger electroconductivity. 

Chow et al. [22] used spray drying to prepare nanosize hydroxyapatite (HA) particles. They used a nozzle to spray the acidic calcium phosphate solutiou aud an electrostatic precipitator to collect nanosize powder. Their high-resolution transmission electron microscopy (TEM) showed that the particles, some of which were only 5 nm in size, exhibited... 

Metallic powders have a vast range of applications in chemistry [51]. Amongst these lie their use in catalysis [52] and organometalKc chemistry [53, 54). However, whilst larger particles are readily available, until now the preparation of nanosized powders has been difficult and expensive, Kmiting their commercial viability. 

Fig. 5.14 Sonochemically prepared nanosize barium titanate powder [272]...

Table 1. Physical properties of nanosized TiOj powders prepared at different HNO3 and TENOH concentration and their photocatalytic activity...

As mentioned before in order to determine whether or not the free A1 formed upon decomposition of LiAlH /LijAlH in the composite could act as a catalyst, we also prepared composites with the content of A1 equivalent to the content of A1 in the Awt%LiAlH. Their DSC desorption peak temperature maxima are also plotted in Fig. 3.31. The composites with the equivalent content of A1 do not seem to follow the ROM behavior. Therefore, one can tentatively conclude that the underlying physical mechanism for the ROM behavior is not related to the catalytic effect of free Al. However, this possibility, however remote, cannot be completely ruled out of hand because the particle size of free Al formed upon decomposition might be much smaller than that obtained by ball milling of Al metal powder added to MgH powder. Nanosized free Al could aquire catalytic behavior. However, at the moment we do not have any evidence for that. 

Zhang Q, Gao L, Guo J (2000) Effects of calcination on the photocatalytic properties of nanosized TiOj powders prepared by TiCl hydrolysis. Appl Catal, B 26 207-215... 

Pyrotechnics will take an important step forward by making use of several nanosized fuels and oxidizers for pyrotechnic formulations in the near future. As a result, the performance of such pyrotechnic formulations will become considerably better and thus the problem of availability of space for pyrotechnic devices will not remain as critical as it is now, because several metal powders and oxidizers are commercially available at the nanoscale these days. Before we discuss nanosized fuels, oxidizers and their formulations, it is considered essential to describe in brief nanomaterials (NMs)including carbon nanotubes (CNTs), their methods of preparation, their properties in general, and some important applications. 

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