Made to order
doi:10.1038/nindia.2009.262 Published online 31 July 2009
Exposure to heat can work wonders for nano-sized multilayer iron films yielding structurally better nanomaterials for technical applications, claims an Indo-German research team1.
Atoms migrate from one site to another inside the iron films made of tiny grains. Known as diffusion, such migration reshapes the structure of nano-sized iron films. Diffusion is a very fundamental process in solids, which controls a lot of processes, such as grain growth, mechanical deformation, and stress relaxation. In other words, it influences the whole nanostructure.
At room temperature, diffusion is so slow that it couldn't be observed in years. But on exposure to heat, it happens within days or hours. To achieve this, the researchers produced iron films of 150 nm thickness on silicon substrate. The films contained grains of about 10-20 nm diameter. Then they heated the films in a vacuum furnace between 300 and 500 degrees C and studied diffusion using neutron reflectrometry.
The study found diffusion lengths in iron films between 0.8 and 2.5 nm.
The authors of this work are from: Institute of Metallurgy, Materials Physics Group, Clausthal University of Technology, Clausthal-Zellerfeld and GKSS Research Center Geesthacht GmbH, Geesthacht, Germany; and UGC–DAE Consortium for Scientific Research, Indore, India.
- Chakravarty, S. et al. Self-diffusion and defect annihilation in nanocrystalline Fe films probed by neutron reflectometry. Phys. Rev. B. 80, 014111 (2009) | Article |