High-pressure and high-temperature synthesis of the cubic Ti O2 polymorph

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 48GPa and temperatures between 1900 and 2100K , 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)Å . Reflections of the cubic phase can be followed on decompression at ambient temperatures down to about 9GPa . Our observations suggest that at high temperature and elevated pressure both IV AB and IV A element dioxides follow a common transformation path.