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The growth mechanism of WS2 nanotubes in the large-scale fluidized-bed reactor is studied in greater detail. This study and careful parameterization of the conditions within the reactor lead to the synthesis of large amounts (50–100 g/batch) of pure nanotubes, which appear as a fluffy powder, and (400–500 g/batch) of nanotubes/nanoplatelets mixture (50:50), where nanotubes usually coming in bundles. The two products are obtained simultaneously in the same reaction but are collected in different zones of the reactor, in a reproducible fashion. The characterization of the nanotubes, which grow catalyst-free, by a number of analytical techniques is reported. The majority of the nanotubes range from 10 to 50 micron in length and 20–180 nm in diameter. The nanotubes reveal highly crystalline order, suggesting very good mechanical behavior with numerous applications.

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Metal dichalcogenide nanotubes and in particular those of WS 2 were shown to exhibit some unique physical and chemical properties, which offer numerous applications for this kind of nanophase material. Using a fluidized bed reactor (FBR), WS 2 nanotubes were obtained in substantial amounts recently, rendering a systematic study of their properties possible. The FBR synthesized nanotubes are multiwalled (5-7 layers); open-ended; long (v0.5 mm), and with diameters of 15-20 nm. They are therefore distinguishable from the previously reported WS 2 nanotubes which were shorter, bulkier and with closed ends. Careful analysis by various electron microscopy techniques is used in the present study to shed some light on the growth mechanism of these newly synthesized nanotubes. The proposed growth mechanism model differs markedly from the previously reported mechanisms of formation of both fullerene-like WS 2 nanostructures and inorganic nanotubes of WS 2 .

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