Successfully developed the method of rapid inspection of nanotube quality

Scientists at the National Institute of Technology and Standards NIST have developed a new, highly sensitive method capable of assessing the quality of carbon nanotubes. Potential tests at first suggest that this method is not only faster than standard analytical techniques, but also effectively test the purity and robustness of smaller pieces than current and test get the variability of samples in a better way.

Carbon nanotubes have many unique properties with thermal and electrical conductivity, which can be useful in areas such as aerospace, microelectronics and biotechnology. However, these properties can vary greatly, depending on the size, the unchanging nature and the purity of the nanotube. Nanotube samples often contain a significant amount of more common forms of carbon as well as metal particles left from the catalyst used in production.

NIST Academy's new method involves spraying the coating of nanotube onto quartz crystal, slowly heating the coated metal and measuring the change in the resonant frequency of the tube when other carbon forms each other evaporates.

This frequency varies in proportion to the volume of the coating, and scientists use this as a measure of durability at different temperatures to measure the strength of the sample tubes. Quartz crystal techniques, techniques that can only indicate mass changes in a few nanograms, have been used for other tasks to find toxic gases and measure molecular interactions.

NIST researchers tested dozens of sample tubes from a group of single-walled carbon nanotubes produced for consumption and then compared the measurement results with the new method with the measurement results. Standard engineering, thermogravimetric analysis, and scanning electron microscopy results. Both methods show that these tubes contain large amounts of amorphous carbon as well as the remaining metal particles . But the carbon crystal method can achieve results from only a few micrograms of material, compared to milligrams of material in the technique of thermal weight analysis, and also indicates some degree of variability in the tubes. samples are tested. This new technique also uses simpler devices than thermal weight analysis techniques.

Although the difference between nanotubes seems to be difficult to detect, they can still affect the viability of the product, because with only a small variation in the composition of the material also affecting electrical and electrical properties, as well as the lack of variability that could lead to more nanotubes, and of course these nanotubes are very expensive.

NIST scientists conducted tests with the help of students at Colorado -Boulder University and Rensselaer Polytechnic, Troy, NY.

The NIST Institute's new method has the ability to quickly check the quality of carbon nanotubes and this method is evaluated relatively through the results from the electron scanning microscope, which shows the composition irregular formations such as large nanotubes, and impurities such as metal particles (color added).(Photo: NIST)

Thanh Van