Anatase


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anatase

[′an·ə‚tās]
(mineralogy)
The brown, dark-blue, or black tetragonal crystalline form of titanium dioxide, TiO2; used to make a white pigment. Also known as octahedrite.

Anatase

 

a mineral, one of the three natural polymorphous modifications of titanium dioxide. The mineral crystallizes in a tetragonal system. Its hardness on the mineralogical scale is 5.5–6.0; its density is 3,820–3, 950 kg per cu m. Anatase contains impurities of iron, sometimes tin, and niobium (up to 2.16 percent Nb2O5). It forms small (up to 1 cm), sharp dipyramidal crystals, as well as crystals of plate and prismatic form. Its cleavage is good and in several directions. The color of anatase is greenish yellow to brownish (wiserine) or bluish gray to almost black. It has a bright, diamondlike luster. Upon heating to 620–650°C, anatase changes into rutile. Anatase is found in hydrothermal, crystal-bearing veins of a particular “alpine” type, in metamorphic rock, in placers, and as a product of ilmenite breakdown.

titanium dioxide

A white pigment having a very high opacity; used in paints; occurs in two crystalline forms, anatase and rutile, of which the latter has higher opacity.
References in periodicals archive ?
For the commercial oxide Ti[O.sub.2] P25, a mixture of anatase and rutile with about 70% anatase, the band gap energy ([E.sub.g]) reported in the literature is around 3.2 eV [28, 29], an equally reported value for pure anatase [23, 24].
Figure 3d reveals the shift in the position of the anatase (101) main peak as a function of the Zr concentration in the solution after annealing at 500 [degrees]C.
We saw no significant changes when using amorph Ti[O.sub.2], PEG-brookite, rutile, anatase, and amorph BSA nanoparticles [Figure 3].
The XRD (Figure 3) indicates that the photocatalytic powders are mainly made of the anatase crystalline phase in comparison to characteristic peaks reported in the standard (R) JCPDS-73-1764.
In this context, the present work aimed to create a more biocompatible surface through anatase formation by pulsed current at different frequencies and room temperature for anodisation processes.
where [E.sub.molecule] is the energy of the individual gas molecule, [E.sub.sur] is the energy of the insolated anatase Ti[O.sub.2] (101) surface, and [E.sub.sur+molecule] is the total energy of the anatase Ti[O.sub.2] (101) surface model after gas molecule adsorption.
The average crystallite size for anatase and rutile ([D.sub.anatase] and [D.sub.rutile], resp.), the anatase content, [A.sub.p], estimated with the Spurr-Myers equation [10] from the main diffraction peaks, and the pH of the acidic solution (HN[O.sub.3] and HCl) are shown in Table 1.
As shown in Figure 1(a), all the diffraction peaks matched well with anatase Ti[O.sub.2] (JCPDS number 021-1272), which confirms that the pyrolysis temperature is appropriate to gain high-purity anatase Ti[O.sub.2].
The market in the anatase segment is expected to witness high growth rate during the forecast period because of the increasing demand for the anatase grade of titanium dioxide for paints and coatings applications for the construction industry.
To prepare the Ti[O.sub.2] mixed with activated carbon samples, it was used Ti[O.sub.2] anatase phase with 99.5% purity (Aldrich), grain size 21 nm ~ and activated carbon powder (Aldrich).