High-pressure and high-temperature synthesis of the cubicTiO2polymorph

High Pressure and Chemical Bonding in Materials Chemistry

“…The transition rutile → fluorite is observed for TiO 2 [8], ZrO 2 [9] or HfO 2 [10]. On the other hand, the transition rutile → pyrite is induced for GeO 2 [11], SnO 2 [12], PbO 2 [13] and RuO 2 [13].…”

Prediction of electronic, structural and elastic properties of the hardest oxide: TiO2

“…The TiO 2 in the cotunnite phase has a measured bulk modulus value of 431 GPa [1,5] and equilibrium volume of 96 Å 3 . M. Mattessini and collaborators [2] showed that under high pressures and temperatures, the TiO 2 can also become a cubic phase, in analogy with ZrO 2 and HfO 2 , emphasizing that the conditions of high temperature help to show the strong similarity in the phase diagram of the group IV oxides. The suggestion [2] that these likenesses could be attributed to a common ionic component, that exists in these oxides in the metal-oxygen bonds, as found in this work.…”

Compression Behavior of Zr-doped Nanoanatase

“…At pressures < 5 GPa the stable form of TiO 2 is rutile (tetragonal, space group P4 2 /mnm, coordination number CN = 6), but also anatase (tetragonal, I4 1 /amd, CN = 6) and brookite (tetragonal, Pcab, CN = 6) exist as metastable forms as well as a number of other modifications [6]. High-pressure polymorphs are the orthorhombic forms TiO 2 -II (columbite structure, space group Pbcn, CN = 6) at pressures of 5 to 8 GPa [7 -9], MI (baddeleyite structure, P2 1 /c, CN = 7) to 20 GPa [10,11] and OI (Pbca, CN = 7) to 50 GPa [12], and at higher pressures OII (cottunite structure, Pnma, CN = 9) [13,14] along with a cubic phase with the space group Fm3m or Pa3 and CN = 9 [15] (see also references in Table 1). …”