• journal_title：American Mineralogist
• Contributor：Alberto Escudero ; Falko Langenhorst
• Publisher：Mineralogical Society of America
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2012.3941
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：97
• issue：4
• firstpage：524
• section：Articles

Silicon incorporation in TiO₂ phases at increasing pressures until 20 GPa at 1300 °C has been studied by XRD and TEM. Rutile is the stable Si-doped TiO₂ phase until at least 7 GPa, transforming into α-PbO₂ structured TiO₂ between 7 and 10 GPa. The further transformation to the TiO₂ polymorph with the baddeleyite structure, akaogiite, has not been observed on the quenched samples. XRD and TEM-EDX data suggest that the Si-doped TiO₂ akaogiite polymorph is non-quenchable and reverts to α-PbO₂ structured TiO₂ when releasing the pressure. This transformation gives rise to α-PbO₂ structured TiO₂ grains decorated with π fringes stacking faults. Silicon solubility in TiO₂ phases increases with increasing the synthesis pressure until 16 GPa, implying the substitutional solid solution to be the mechanism of solubility. The influence of the dopants on the stability of the rutile and the α-PbO₂ structured TiO₂ has also been analyzed.