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9/1/12

Nanocrystalline alloys

Nanocrystals for ferro electricity
Ferro electricity
The phenomenon of ferro electricity was discovered in 1921 using Rochelle salt. Barium titanate (BaTiO3) is a ferroelectric material used in making ferro electricity. There are more than 250 materials that exhibit ferroelectric properties, which include;     Lead titanate, Lead zirconate titanate and Lead lanthanum zirconate titanate. Ferroelectric materials have a permanent dipole moment, like their ferromagnetic counterparts. However, in ferroelectrics, the dipole moment is electric and not magnetic and so can be oriented using electric fields rather than magnetic ones to allow electrically digital information to be stored in ferroelectric thin films.
Applications of ferroelectric materials
Ferroelectric materials are used in making capacitors, non-volatile memory, piezoelectrics for ultrasound imaging and actuators, electro-optic materials for data storage applications, thermistors, switches known as transchargers or transpolarizers, oscillators and filters, light deflectors, modulators and displays.
Nanostructured metals
Nanostructured metals exhibit interesting and useful properties owing to their extremely fine structural length scale.  Unfortunately, controlling grain size in the nanocrystalline regime has proven difficult as these materials represent a classical far-from-equilibrium state, containing a large volume fraction of high-energy interfaces.  Alloying presents an opportunity to reduce the energy penalty associated with nanostructure formation.
GeTe is a semiconducting ferroelectric and BaTiO3 is a typical oxide ferroelectric. Researchers at the Lawrence Berkeley National Laboratory and the University of California at Berkeley have studied maps of ferroelectric distortions in germanium telluride and barium titanium oxide for making next-generation non-volatile memory devices that would store terabits of data per square inch.
The researchers analysed ferroelectric ordering in single nanocrystals of GeTe and BaTiO3 by directly imaging the structural distortions associated with ferro electricity.
Non-volatile memories made from these ferroelectric nanocrystals could have data-storage densities and used as nanoscale piezoelectric actuators and transducers in future nano electromechanical systems (NEMS) devices.
The results of the study indicate that local atomic displacements remain largely linearly ordered in a single domain, leading to a net electrical polarization meaning that useful ferroelectric properties, including polarization switching and piezoelectricity, can be maintained down to dimensions of just a few nanometers
Nanocrystalline alloys for heat stability
Researchers at the Massachusetts Institute of Technology have produced a new tungsten-based nanocrystalline alloy that is stable above 1000 °C. Nanocrystalline metals are much stronger than their bulk counterparts but unstable, because grains of the nanocrystals can grow and merge together at high temperatures when metal softens.
Researchers have created alloy based on tungsten and titanium containing about 20 atomic % of titanium with grains of 20 nm in size. It was stable for a long time at annealing temperatures of 1100 °C and retained its exceptional strength.
It can find use in applications where high-impact resistance is needed, such as in industrial machinery or in armour and to make new nanostructured materials with equally good or even better strength and stability, and additional desirable properties like corrosion resistance.


1 Responses to “Nanocrystalline alloys”

nano said...
October 8, 2012 at 10:12 PM

very good article. I an studying nano technology. I known that nano technology is widely used in industrial materials. but after reading your blog post i get nice information regarding use of nano technology in jewellery. thanks for good information. nano ornaments are made from nano technology.nanoalloy is used in this ornament metals.


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