Self-assembled nanocrystals discovered in Chelyabinsk meteorite.

Current interest in nanomaterials is focused mostly on artificial materials fabricated for various applications. However, naturally occurring nanocrystal arrays, like those recently found in the meteorite that fell near Chelyabinsk in Russia on 15 February, 2013, can provide some new insights into the nature of nanomaterials, including the conditions for their natural occurrence. Here we report the results of our spectroscopic investigation of a fragment of the Chelyabinsk meteorite. The atomic structure of a fragment of the Chelyabinsk meteorite was studied using high-resolution transmission electron microscopy. Elemental and phase analysis of the object that was carried out by energy dispersive X-ray spectroscopy and electron diffraction revealed the presence of crystalline phases of different chemical compounds specific to meteorites of the LL group. In addition to single-crystal inclusions, extensive areas with ferropericlase nanocrystals having characteristic sizes from 3 to 15 nm were found in the structure of the meteorite. The study of the meteorite employing combination scattering of light (Raman) and photoluminescence spectroscopy methods has revealed quantum effects of ferropericlase nanoparticles and related photoluminescence with a maximum in the range of 675-800 nm.