• journal_title：American Mineralogist
• Contributor：Fabrice Brunet ; Anne-Marie Flank ; Jean-Paul Itié ; Tetsuo Irifune ; Pierre Lagarde
• Publisher：Mineralogical Society of America
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2007.2570
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：92
• issue：7
• firstpage：989
• section：Articles

Phosphorus, a group V element, has always been found so far in minerals, biological systems, and synthetic compounds with an oxygen coordination number of four (i.e., PO₄ groups). We demonstrate using phosphorus K-edge XANES spectroscopy that this element can also adopt a sixfold oxygen coordination (i.e., PO₆ groups). This new coordination was achieved in phosphorus-doped (1 wt% P₂O₅ level) SiO₂-stishovite synthesized at 18 GPa and 1873 K and quenched to ambient conditions. This change of phosphorus coordination at high pressure within a dense silicate structure is particularly relevant to phosphorus mineralogy (and geochemistry) in the deep Earth. With a mantle abundance below 0.25 wt%, phosphorus has been shown to be mainly hosted by silicates (e.g., olivine) in the Earth’s upper-mantle, in the fourfold-coordinated silicon sites. In the lower mantle where all silicon is sixfold coordinated, we show here that phosphorus has the crystal-chemical ability to remain incorporated into silicate structures.