Experimental and theoretical calculations recently indicated that TiO2 could have a series of high-pressure phases with a hardness possibly approaching that of a diamond. The high-pressure, high-temperature phase equilibria have been studied  with special emphasis on the rutile alpha-PbO2 type phases. It is found that the phase boundary, when plotted in a pressure - temperature diagram, changes from negative to positive slope with increasing temperature at about 6 GPa and 850 C. For nanophase material, the phase boundary is shifted towards lower pressure. The room-temperature bulk moduli are 210, 258 and 290 GPa for rutile, the alpha-PbO2 type phase and the baddeleyite type phase, respectively.
|Effective start/end date||01/01/1998 → 31/12/2000|