Baddeleyite-Type High-Pressure Phase of TiO 2

A high-pressure phase of TiO 2 , which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770°C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO 2 at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.