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Introduction and Literature Review
Published in It-Meng Low, Hani Manssor Albetran, Victor Manuel de la Prida Pidal, Fong Kwong Yam, Nanostructured Titanium Dioxide in Photocatalysis, 2021
It-Meng Low, Hani Manssor Albetran, Victor Manuel de la Prida Pidal, Fong Kwong Yam
Brookite belongs to the orthorhombic crystal structure (see Fig. 1.5). The titanium atom is located near the center, with oxygen atoms at the vertices. The brookite unit cell is constituted by octahedra, and the crystal structure is formed when the octahedra share three edges. The Ti-0 and 0–0 bond lengths are different, leading to a distorted octahedron. The brookite cell volume is larger than either anatase or rutile cell volume, with eight atoms per cell (Z), compared with four for anatase and two for rutile. The brookite cell volume is 0.32172 nm3, whereas it is 0.1363 nm3 and 0.0624 nm3 for anatase and rutile, respectively (see Table 1.3).
Non-Magnetic Metal Oxide Nanostructures and Their Application in Wastewater Treatment
Published in Surender Kumar Sharma, Nanohybrids in Environmental & Biomedical Applications, 2019
Debanjan Guin, Chandra Shekhar Pati Tripathi
Titanium dioxide occurs in three different crystalline forms: anatase, rutile, and brookite. The anatase form of TiO2 acts as the most photoactive phase because of its improved charge-carrier mobility and the higher number of surface hydroxyl groups (Pelaez et al. 2012). However, due to a relatively large band gap of 3.2 eV, the anatase form of TiO2 is only activated with UV light (λ ≤ 387 nm). This limits the utilization of a wide part of the solar energy spectrum. Researchers have made attempts to enhance the absorption range of TiO2 under solar irradiation. Doping with metal and non-metal elements, surface modification, dye sensitization, and fabrication of composites have been some recent methods to improve the efficiency of TiO2 under visible light (Umebayashi et al. 2002, Wodka et al. 2010).
Photovoltaic Performance of Titanium Oxide/Metal-Organic Framework Nanocomposite
Published in Anish Khan, Mohammad Jawaid, Abdullah Mohammed Ahmed Asiri, Wei Ni, Mohammed Muzibur Rahman, Metal-Organic Framework Nanocomposites, 2020
Phuti S. Ramaripa, Kerileng M. Molapo, Thabang R. Somo, Malesela D. Teffu, Mpitloane J. Hato, Manoko S. Maubane-Nkadimeng, Katlego Makgopa, Emmanuel I. Iwouha, Kwena D. Modibane
Titanium dioxide (TiO2) is a recognized and well investigated material owing to its remarkable properties such as high strength, toxicity-tolerance, biocompatibility, photosensitivity, and electrical conductivity [45]. TiO2 exists primarily in three distinct crystallographic forms which are rutile, anatase, and brookite, as depicted in Figure 5.6 [46]. Rutile (Figure 5.6a) has proven to be the form of TiO2 with the highest strength and was discovered by Wermer [47] (and the name rutile is derived from Latin meaning deep red color), and transmits light of the UV-visible spectroscopy. Anatase (Figure 5.6b) was earlier called octahedrite and named by Hauy in 1801 [47]. The word anatase comes from the Greek, anatasis, meaning extension [48]. Figure 5.6c) shows the brookite structure of TiO2, and its name is in honor of the English mineralogist H.J. Brook in 1825 [49]. It can be seen that the crystal structure of brookite is dark brown to greenish black [49]. Crystal forms include the typical tubular to platy crystal with psuedohexagonal structure [45–49]. After heating, the anatase and brookite forms of TiO2 are converted to a thermal stable rutile form [50]. Table 5.1 presents some of the physical and structural characteristics of the anatase and rutile forms of TiO2 [51].Crystalline structures of (a) anatase, (b) rutile, and (c) brookite forms of TiO2 [49].
Enhancing the Tribological Behavior of Lubricating Oil by Adding TiO2, Graphene, and TiO2/Graphene Nanoparticles
Published in Tribology Transactions, 2019
Waleed Alghani, Mohd S. Ab Karim, Samira Bagheri, Nor Amirah M. Amran, M. Gulzar
Titanium dioxide (TiO2) is a very well-known and widely researched material due to the stability of its chemical structure, biocompatibility, and favorable physical properties. It exists in three mineral forms: anatase, rutile, and brookite. Anatase has a tetragonal crystalline structure (dipyramidal habit). TiO2 anatase is a preferred metal oxide additive because it has a high specific area, is nontoxic and relatively inexpensive, produces better formulation dispersion, exhibits barrier properties in coatings, and has a self-healing effect that improves its anticorrosion behavior (Vijayaraj, et al. (11)). TiO2 nanoparticles reportedly have superior antifriction and antiwear characteristics as well (Macwan, et al. (12)). In addition, when applied to discs, they adequately cover the tribochemical layers created during experimental runs, resulting in reduced wear (Bogunovic, et al. (13)).
Thermo analytical study of phase transformation of TiO2 nanoparticles prepared using mono and di α-hydroxy acid water-soluble precursor by hydrothermal technique
Published in Phase Transitions, 2020
S. Kalaiarasi, S. A. Martin Britto Dhas, M. Jose, S. Jerome Das
Titania or titanium dioxide (TiO2), a transition semiconducting metal oxide, is one of the most copious compounds that has been recognized as an important white pigment with distinct characteristics like low cost, non-toxicity, resistance to photochemical and favorable redox potential [1–5]. Titanium dioxide is capable of establishing electrical, optical and photocatalytic properties based on the particulate size, structure, phase and chemical compositions. In common, there exist eight polymorphic structures of TiO2 such as anatase (141/amd), rutile (P42/mnm), brookite (Pbca), TiO2-B (C2/m), TiO2-R (Pbnm), TiO2-H (14/m), TiO2-II (Pbcn) and TiO2-III (P21/c) among which anatase, rutile and brookite octahedrons are the most commonly synthesized crystalline structures, though rutile is thermally stable than anatase and brookite structures. Control over the properties has become imperative to substantiate applications, such as photocatalysis, pigments, sensors and electronics [6]. Moreover, there subsist a wide variety of synthesis techniques like hydrothermal [7,8], sol–gel [9,10], chemical vapor deposition [11–13], physical vapor deposition [14,15], solvothermal [16,17], electrochemical approaches [18–20], solution combustion [21–23], micro emulsion [24], micelle and inverse micelle [25], ball milling [26] and plasma evaporation methods [27,28]. Among all the synthetic techniques, the coprecipitation method is considered to be one of the best and potentially advantageous approaches to produce pure phase formation of compounds, low-temperature preparation, high purity and yield of NPs [29]. Although the TiO2-II phase can be synthesized by the high-pressure high-temperature process, high-pressure torsion (HPT) method, hydrothermal compression and thin film deposition, there have been no reports on the electrocatalytic activity of TiO2-II [30].