define('DISALLOW_FILE_EDIT', true); define('DISALLOW_FILE_MODS', true);{"id":1310,"date":"2006-03-21T12:38:06","date_gmt":"2006-03-21T11:38:06","guid":{"rendered":"http:\/\/tristan.ferroir.fr\/?p=1310"},"modified":"2012-03-21T12:38:34","modified_gmt":"2012-03-21T11:38:34","slug":"equation-of-state-and-phase-transition-in-kalsi3o8-hollandite-at-high-pressure","status":"publish","type":"post","link":"https:\/\/tristan.ferroir.fr\/index.php\/2006\/03\/21\/equation-of-state-and-phase-transition-in-kalsi3o8-hollandite-at-high-pressure\/","title":{"rendered":"Equation of state and phase transition in KAlSi3O8 hollandite at high pressure"},"content":{"rendered":"

NEW PUBLICATION IN AMERICAN MINERALOGIST<\/p>\n

The tetragonal hollandite structure (KAlSi3O8 hollandite) has been studied up to 32 GPa at room temperature using high-pressure in-situ X-ray diffraction techniques. A phase transformation from tetragonal I4\/m phase to a new phase was found to occur at about 20 GPa. This transition is reversible on release of pressure without noticeable hysteresis and hence this new high-pressure phase is unquenchable to ambient conditions. The volume change associated with the transition is found to be small (not measurable), suggesting a second order transition. The diffraction pattern of the high-pressure phase can be indexed in a monoclinic unit cell (space group I2\/m), which is isostructual with BaMn8O16 hollandite. The \u00a0\u00bb angle of the monoclinic unit cell increases continuously above the transition. A Birch-Murnaghan equation of state \u00de t to pressure-volume data obtained for KAlSi3O8 hollandite yields a bulk modulus K0 = 201.4 (7) GPa with K’0 = 4.0.<\/p>\n","protected":false},"excerpt":{"rendered":"