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Posted: Aug 31, 2012
Researchers reoprt a stable body-centred tetragonal phase in silver nanoparticles
(Nanowerk News) So far, stable non-face-centered cubic phases in noble metal nanoparticles have not been reported yet. Crystallization of noble metal atoms usually leads to the highly symmetric face-centred cubic phase that represents the thermodynamically stable structure.
Introducing defective microstructures into a metal crystal lattice may induce distortions to form non-face-centered cubic phases when the lateral dimensions of objects decrease down to nanoscale.
Schematic drawing of a silver nanowire with fivefold symmetry.
They report that the body-centered tetragonal phase originates from the distortion of cubic silver lattices due to internal strains in the twinned nanoparticles. The lattice distortion in the centre of such a nanoparticle is larger than that in the surfaces, indicating that the nanoparticle is composed of a highly strained core encapsulated in a less-strained sheath that helps stabilize the strained core.