• journal_title：American Mineralogist
• Contributor：Hitoshi Yusa ; Masaki Akaogi ; Nagayoshi Sata ; Hiroshi Kojitani ; Yoshitaka Kato ; Yasuo Ohishi
• Publisher：Mineralogical Society of America
• Date：2005-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2005.1835
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：90
• issue：5-6
• firstpage：1017
• section：Letters

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.