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Licensed Unlicensed Requires Authentication Published by De Gruyter March 28, 2015

Letter: Unquenchable hexagonal perovskite in high-pressure polymorphs of strontium silicates

  • Hitoshi Yusa EMAIL logo , Masaki Akaogi , Nagayoshi Sata , Hiroshi Kojitani , Yoshitaka Kato and Yasuo Ohishi
From the journal American Mineralogist


The presence of hexagonal silicate perovskite (6H-BaTiO3 type) was confirmed in the SrSiO3 compound by in-situ angle dispersive X-ray diffraction at high pressure. The perovskite was crystallized from pressure-induced amorphous SrSiO3 in a diamond anvil cell by laser heating at 35 GPa. On releasing the pressure, the perovskite also changed into an amorphous state as does CaSiO3 perovskite. This SrSiO3 perovskite, with a tolerance factor greater than unity, forms a face-sharing SiO6 octahedron, which leads to a structure with hexagonal symmetry. Incorporation of Sr into CaSiO3 perovskite in the early stage of the differentiation in the Earth's mantle might have influenced the symmetry of CaSiO3 perovskite in the present lower mantle. As far as we know, this is the first report suggesting the existence of hexagonal perovskite in silicates.

Received: 2004-10-19
Accepted: 2005-2-25
Published Online: 2015-3-28
Published in Print: 2005-5-1

© 2015 by Walter de Gruyter Berlin/Boston

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