Dr. Çetiner’s Blogs (Prof. Dr. Gültekin Çetiner)

A new album titled Nanotechnology Pictures was added to Photo Gallery. If you want to share interesting pictures of Nanotechnology materials, products, carbon nanotubes, or pictures regarding nano processes, you can share in the album. The link for the album is http://www.drcetiner.org/photo_gallery/main.php?g2_itemId=19631

Carbon nanotubes (CNTs) are an allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized.

Nanotubes are members of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).

The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. Nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, which is stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into “ropes” held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.

Sabres from Damascus, now in Syria, date back as far as 900 AD. Strong and sharp, they were forged from Indian steel called wootz, reports Nature.

Peter Paufler of the Technical University of Dresden, Germany and colleagues studied samples of a 17th-century sword under an electron microscope and found that wootz has a microstructure of nano-metre-sized tubes, just like carbon nanotubes used in modern technologies for their lightweight strength.

The researchers think that the sophisticated process of forging and annealing the steel formed the nanotubes and the nanowires, and could explain the amazing mechanical properties of the swordsWootz’s ingredients include iron ores from India that contain transition-metal impurities. It was thought that these impurities helped cementite wires to form, but it wasn’t clear how. Paufler thinks carbon nanotubes could be the missing piece of the puzzle.

At high temperatures, the impurities in the Indian ores could have catalysed the growth of nanotubes from carbon in the burning wood and leaves used to make the wootz, Paufler suggests. These tubes could then have filled with cementite to produce the wires in the patterned blades, he says.