High-pressure and high-temperature synthesis of the cubic TiO2 polymorph -: art. no. 212101

We report on an in situ observation of a cubic titanium dioxide polymorph. Experiments conducted on an anatase sample as starting material using a laser-heated diamond-anvil cell have shown that at a pressure of 48 GPa and temperatures between 1900 and 2100 K, the x-ray diffraction pattern contains reflections of two phases: the known cotunnite-structured TiO2 and the new cubic phase with lattice parameter a=4.516(1) Angstrom. Reflections of the cubic phase can be followed on decompression at ambient temperatures down to about 9 GPa. Our observations suggest that at high temperature and elevated pressure both IV AB and IV A element dioxides follow a common transformation path.