Structural, electronic and optical properties of brookite phase titanium dioxide

DFT study of TiO2 brookite (210) surface doped with silver and molybdenum

“…Figure 2 shows the band structures of (a) the pure brookite bulk structure and (b) the undoped brookite (210) surface. It can be observed that the calculated band gap energy of the bulk brookite is 2.360 eV, which is less than 3.400 eV obtained experimentally [8] and comparable to 2.485 eV obtained computationally using GGA [51]. The disparity between the experimental band gap energy and the calculated band gap energy of this work of the bulk brookite is attributable to the functional tendency of GGA to underestimate the band gap energy due to the exchange correlation energy [52].…”

“…The undoped surface shows no response after 500 nm, whereas the imaginary parts of dielectric function for the doped surfaces proceed and show an enhanced response in the near-infrared region, which enhanced the light absorption. From the dielectric function, the Kramers-Kronig transformation is used to obtain the real part n(ω) and the imaginary part k(ω) (extinction coefficient) of the refractive index as [51]:…”

Inorganic Structural Chemistry of Titanium Dioxide Polymorphs

“…Various factors, such as longer-range electrostatic interactions, chemical bonding energy, and structural strain energy, may all have an effect on the actual phase stability. The phase stability of TiO 2 polymorphs, including anatase and brookite, was investigated using ab initio calculations, but no conclusive results appear to have been obtained due to severe parameter dependence. ,− The fact that the four polymorphs actually appear in different conditions indicates that their thermodynamic energy differences are quite small.…”

“…TiO 2 occurs naturally in four distinct forms: ,, rutile, which is the most abundant and forms at high temperatures; anatase, which forms at low temperatures and in nanoparticles; brookite, a metastable phase that forms under certain conditions; , the α-PbO 2 -type form, which is stabilized at high pressures of 4.5–7 GPa; , pyrite- and fluorite-type crystal structures, which form at pressures greater than 13 GPa, are omitted from this discussion. Rutile is a relatively common inorganic crystal structure found in a large number of MX 2 (M is a cation; X is an anion) compounds. ,, On the other hand, anatase has been extensively studied for its photocatalytic activity in nanoparticles, and its crystal structure has been determined to be unique to TiO 2 .…”

“…In this Article, from the perspective of inorganic structural chemistry, I discuss the origin and correlation of the crystal structures of titanium dioxide (TiO 2 ) polymorphs, a typical inorganic compound. TiO 2 occurs naturally in four distinct forms: 4,7,12 rutile, which is the most abundant and forms at high temperatures; anatase, which forms at low temperatures and in nanoparticles; 13 brookite, a metastable phase that forms under certain conditions; 14,15 the α-PbO 2 -type form, which is stabilized at high pressures of 4.5−7 GPa; 16,17 pyrite-and fluorite-type crystal structures, which form at pressures greater than 13 GPa, are omitted from this discussion. Rutile is a relatively common inorganic crystal structure found in a large number of MX 2 (M is a cation; X is an anion) compounds.…”