Tungsten sulphide nanotubes.(Nanomaterials)

Researchers at the Weizmann Institute of Science, Israel, and the Technical University of Dresden, Germany, have developed tungsten sulphide nanotubes with a tensile strength of around 16 GPa. The nanotubes could find application in novel nanocomposites, the researchers predict.

Dr Reshef Tenne, alongside colleagues at the Weizmann Institute, tested the mechanical properties of the nanotubes in a high resolution scanning electron microscope. They attached the nanotubes to two atomic force microscope cantilevers, applying the force through the upper cantilever.

The researchers believe that this technique applied force only to the outer shell of the nanotube.

The nanotubes exhibited the following properties:

* a Young's modulus of 152 GP (with a variance of about 6%);

* a strength of 3.7-16.3 GPa (with a variance of about 11%);

* an elongation of 5-14% (with a variance of about 0.1%).

The strongest nanotubes had a strength that was around 11% of the Young's modulus. This roughly corresponds to the material's theoretical strength, indicating that the nanotubes were largely free of critical defects.

Theoretical modelling of the behaviour of defect-free single-wall molybdenum sulphide nanotubes, which have the same structure as the tungsten sulphide tubes, gave results that agreed with these values. The model suggested that fracture began at atomistic defects.

Dr Tenne said "These materials can be strained to over 12% of their initial length and at the same time yield under tensile stress of about 20 GPa."

The tungsten sulphide nanotubes could have applications in nanocomposites, solid state lubrication and nanomachines, the researchers said.

For further information, contact: Professor Reshef Tenne, Weizmann Institute of Science, Department of Materials and Interfaces, PO Box 26, 76100 Rehovot, Israel; tel: +972-8-934-2394; fax: +972-8-934-4138; E-mail: reshef.tenne@weizmann.ac.il; Internet: www.weizmann.ac.il