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Z. Naturforsch. 2012,
67b, 1016 – 1020
doi:10.5560/ZNB.2012-0110
Low-frequency Vibrational Dynamics of Amorphous and Crystalline Silica
1 AQura GmbH, Rodenbacher Chaussee 4, D-63457 Hanau, Germany
2 Evonik Industries AG, Business Unit Inorganic Materials, Rodenbacher Chaussee 4, D-63457 Hanau, Germany
3 STFC Rutherford Appleton Laboratory, ISIS Facility, Chilton, Didcot, Oxfordshire, OX11 0QX, United Kingdom
Reprint requests to Dr. Peter Albers. Fax: +49 6181 59 3554. E-mail:
peter.albers@aqura.de
Received April 27, 2012 / published online October 8, 2012
Dedicated to Professor Heribert Offermanns on the occasion of his 75th birthday and on the occasion of the 70th birthday of AEROSIL®
Crystalline silica shows strong, sharp signals at about 77 and 130 cm−1 in the inelastic neutron scattering spectrum that are missing or strongly different, broadened and shifted to lower frequency for the case of precipitated and fumed silica. The presence or absence of these signals is a sensitive signature of crystallinity or amorphicity in silica. The low-frequency phonon density of states of precipitated and fumed silica is typical for completely amorphous materials. This observation is in perfect agreement with data from X-ray diffraction and high-resolution transmission electron microscopy. The amorphicity is retained during granulation post-treatments.
Key words: Silica, Amorphous, Crystalline, Vibrational Density of States