{"id":12926,"date":"2017-06-07T23:58:45","date_gmt":"2017-06-07T21:58:45","guid":{"rendered":"http:\/\/karmaka.de\/?p=12926"},"modified":"2017-06-20T07:07:35","modified_gmt":"2017-06-20T05:07:35","slug":"compressional-pathways-of-%ce%b1-cristobalite-structure-of-cristobalite-x-i-and-towards-the-understanding-of-seifertite-formation","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=12926","title":{"rendered":"Compressional pathways of \u03b1-cristobalite, structure of cristobalite X-I, and towards the understanding of seifertite formation.<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"<p>Ana \u010cernok, Katharina Marquardt, Razvan Caracas, Elena Bykova, Gerlinde Habler, Hanns-Peter Liermann, Michael Hanfland, Mohamed Mezouar, Ema Bobocioiu, Leonid Dubrovinsky. <\/p>\n<p>Nature Communications, 2017; 8: 15647<br \/>\nDOI: 10.1038\/ncomms15647<\/p>\n<p><a href=\"https:\/\/www.nature.com\/articles\/ncomms15647\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br \/>\n<a href=\"https:\/\/www.nature.com\/articles\/ncomms15647.pdf\" target=\"_blank\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n<p>&#8220;In various shocked meteorites, low-pressure silica polymorph \u03b1-cristobalite is commonly found in close spatial relation with the densest known SiO2 polymorph seifertite, which is stable above \u223c80\u2009GPa. We demonstrate that under hydrostatic pressure \u03b1-cristobalite remains untransformed up to at least 15\u2009GPa. In quasi-hydrostatic experiments, above 11\u2009GPa cristobalite X-I forms\u2014a monoclinic polymorph built out of silicon octahedra; the phase is not quenchable and back-transforms to \u03b1-cristobalite on decompression. There are no other known silica polymorphs, which transform to an octahedra-based structure at such low pressures upon compression at room temperature. Further compression in non-hydrostatic conditions of cristobalite X-I eventually leads to the formation of quenchable seifertite-like phase. Our results demonstrate that the presence of \u03b1-cristobalite in shocked meteorites or rocks does not exclude that materials experienced high pressure, nor is the presence of seifertite necessarily indicative of extremely high peak shock pressures.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ana \u010cernok, Katharina Marquardt, Razvan Caracas, Elena Bykova, Gerlinde Habler, Hanns-Peter Liermann, Michael Hanfland, Mohamed Mezouar, Ema Bobocioiu, Leonid Dubrovinsky. Nature Communications, 2017; 8: 15647 DOI: 10.1038\/ncomms15647 LINK (OPEN ACCESS) PDF (OPEN ACCESS) &#8220;In various&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41,42,63],"tags":[3942,1844],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/12926"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=12926"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/12926\/revisions"}],"predecessor-version":[{"id":12927,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/12926\/revisions\/12927"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12926"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12926"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12926"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}