Optical properties

IR spectroscopy of quartz nanocrystals formed during intense crushing of a heterogeneous material (granite)

V. I. Vettegren^a, R. I. Mamalimov^a, G. A. Sobolev^b, S. M. Kireenkova^b, Yu. A. Morozov^b, A. I. Smul’skaya<sup>b

a</sup> Ioffe Institute, St. Petersburg
^b Institute of Physics of the Earth, Russian Academy of Scienses

Abstract: The spectra of the imaginary part $\varepsilon''(\nu)$ of the permittivity of quartz single crystals and a heterogeneous material, i.e., pseudotachylite, formed during intense crushing of granite in the region of the seismogenic Earth’s crust fault have been calculated from IR reflection spectra. It has been found that all strong bands in the pseudotachylite spectrum $\varepsilon''(\nu)$ correspond to lattice vibrations in quartz nanocrystals. Bands are asymmetrically broadened due to dielectric and phonon confinements. Linear sizes of quartz nanocrystals have been estimated from the broadening as $\sim$70 nm. The frequency of nanocrystal lattice vibrations is higher than that of the macrocrystal, which is caused by lattice compression. The internal stresses which could cause the observed change in the frequency are $\sim$200 MPa.

Received: 16.05.2011

 English version: Physics of the Solid State, 2011, 53:12, 2495–2499

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