Aluminum incorporation in alpha-PbO2 type TiO2 at pressures up to 20 GPa

作者：Escudero Alberto^*; Langenhorst Falko

来源：Physics of the Earth and Planetary Interiors, 2012, 190: 87-94.

DOI：10.1016/j.pepi.2011.11.002

• TiO2-II
• Alumina
• High-pressure
• TEM
• Al-27 MAS-NMR
• Non-quenchable phases
• Solid solutions
• Stacking faults

Aluminum incorporation into the high pressure polymorph of TiO2 with the structure of alpha-PbO2 has been studied from 10 to 20 GPa and 1300 degrees C by XRD, high-resolution Al-27 MAS-NMR and TEM. Al-doped alpha-PbO2 type TiO2 can be recovered at atmospheric pressure. Al2O3 solubility in alpha-PbO2 type TiO2 increases with increasing the synthesis pressure. The alpha-PbO2 type TiO2 polymorph is able to incorporate up to 35 wt.% Al2O3 at 13.6 GPa and 1300 degrees C, being the substitution of Ti4+ by Al3+ on normal octahedral sites and the formation of oxygen vacancies the mechanism of solubility. The transition to the higher pressure TiO2 polymorph with the ZrO2 baddeleyite structure, akaogiite, has not been observed in the quenched samples at room pressure. The microstructure of the recovered sample synthesized at 16 GPa and 1300 degrees C points to the existence of an intermediate non-quenchable aluminum titanium oxide phase at these conditions.

• 出版日期2012-1