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Artículos de revistas sobre el tema "TiO2 polymorphs"

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Publicado: 25 de mayo de 2024

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1

Eddy, Diana Rakhmawaty, Muhamad Diki Permana, Lintang Kumoro Sakti, Geometry Amal Nur Sheha, Solihudin, Sahrul Hidayat, Takahiro Takei, Nobuhiro Kumada y Iman Rahayu. "Heterophase Polymorph of TiO2 (Anatase, Rutile, Brookite, TiO2 (B)) for Efficient Photocatalyst: Fabrication and Activity". Nanomaterials 13, n.º 4 (12 de febrero de 2023): 704. http://dx.doi.org/10.3390/nano13040704.

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TiO2 exists naturally in three crystalline forms: anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in various photocatalytic applications. However, homophase TiO2 has various disadvantages such as high recombination rates and low adsorption capacity. Meanwhile, TiO2 heterophase can effectively stimulate electron transfer from one phase to another causing superior photocatalytic performance. Various studies have reported the biphase of polymorph TiO2 such as anatase/rutile, anatase/brookite, rutile/brookite, and anatase/TiO2 (B). In addition, this paper also presents the triphase of the TiO2 polymorph. This review is mainly focused on information regarding the heterophase of the TiO2 polymorph, fabrication of heterophase synthesis, and its application as a photocatalyst.
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2

Serga, Vera, Regina Burve, Aija Krumina, Marina Romanova, Eugene A. Kotomin y Anatoli I. Popov. "Extraction–Pyrolytic Method for TiO2 Polymorphs Production". Crystals 11, n.º 4 (16 de abril de 2021): 431. http://dx.doi.org/10.3390/cryst11040431.

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The unique properties and numerous applications of nanocrystalline titanium dioxide (TiO2) are stimulating research on improving the existing and developing new titanium dioxide synthesis methods. In this work, we demonstrate for the first time the possibilities of the extraction–pyrolytic method (EPM) for the production of nanocrystalline TiO2 powders. A titanium-containing precursor (extract) was prepared by liquid–liquid extraction using valeric acid C4H9COOH without diluent as an extractant. Simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA–DSC), as well as the Fourier-transform infrared (FTIR) spectroscopy were used to determine the temperature conditions to fabricate TiO2 powders free of organic impurities. The produced materials were also characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The results showed the possibility of the fabrication of storage-stable liquid titanium (IV)-containing precursor, which provided nanocrystalline TiO2 powders. It was established that the EPM permits the production of both monophase (anatase polymorph or rutile polymorph) and biphase (mixed anatase–rutile polymorphs), impurity-free nanocrystalline TiO2 powders. For comparison, TiO2 powders were also produced by the precipitation method. The results presented in this study could serve as a solid basis for further developing the EPM for the cheap and simple production of nanocrystalline TiO2-based materials in the form of doped nanocrystalline powders, thin films, and composite materials.
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3

Dima, Ratshilumela S., Lutendo Phuthu, Nnditshedzeni E. Maluta, Joseph K. Kirui y Rapela R. Maphanga. "Electronic, Structural, and Optical Properties of Mono-Doped and Co-Doped (210) TiO2 Brookite Surfaces for Application in Dye-Sensitized Solar Cells—A First Principles Study". Materials 14, n.º 14 (14 de julio de 2021): 3918. http://dx.doi.org/10.3390/ma14143918.

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Titanium dioxide (TiO2) polymorphs have recently gained a lot of attention in dye-sensitized solar cells (DSSCs). The brookite polymorph, among other TiO2 polymorphs, is now becoming the focus of research in DSSC applications, despite the difficulties in obtaining it as a pure phase experimentally. The current theoretical study used different nonmetals (C, S and N) and (C-S, C-N and S-N) as dopants and co-dopants, respectively, to investigate the effects of mono-doping and co-doping on the electronic, structural, and optical structure properties of (210) TiO2 brookite surfaces, which is the most exposed surface of brookite. The results show that due to the narrowing of the band gap and the presence of impurity levels in the band gap, all mono-doped and co-doped TiO2 brookite (210) surfaces exhibit some redshift. In particular, the C-doped, and C-N co-doped TiO2 brookite (210) surfaces exhibit better absorption in the visible region of the electromagnetic spectrum in comparison to the pure, S-doped, N-doped, C-S co-doped and N-S co-doped TiO2 brookite (210) surfaces.
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4

Poleti, Dejan, Ljiljana Karanovic, Miodrag Zdujic y Cedomir Jovalekic. "Phase composition of Bi2O3 specimens doped with Ti, Zr and Hf". Journal of the Serbian Chemical Society 77, n.º 8 (2012): 1091–96. http://dx.doi.org/10.2298/jsc110914215p.

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Powder mixtures of ?-Bi2O3 containing 2, 5 and 10 mole % of TiO2, ZrO2 or HfO2 were homogenized, heated at 820?C for 24 h and quenched in air. X-ray powder diffraction technique was used to characterize the prepared samples. In all cases metastable Bi2O3 polymorphs, ?-Bi2O3 or ?-Bi2O3, are found as single or major phases. Addition of Ti4+ ions stabilizes ?-Bi2O3 polymorph, while either Zr4+ or Hf4+ ions stabilize ?-Bi2O3 polymorph. In the samples with 2 and 5 mole % of TiO2 the presence of even two ?-Bi2O3 phases (Bi12TiO20 compound and a very low Ti-doped ?-Bi2O3) was established. Similarly, in the sample with 2 mole % of HfO2 two ?-Bi2O3 phases were found. Phase composition of prepared samples, values of unit cell parameters and the appearance of two polymorphs with identical crystal structure but different unit cell parameters are discussed and compared with known data.
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5

Basavaraj, K., Anupriya Nyayban y Subhasis Panda. "Structural phase transitions and elastic properties of TiO2 polymorphs: Ab-initio study". IOP Conference Series: Materials Science and Engineering 1248, n.º 1 (1 de julio de 2022): 012064. http://dx.doi.org/10.1088/1757-899x/1248/1/012064.

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Abstract TiO2 has tremendously drawn the attention of researchers from the photocatalytic to photovoltaic groups. To explore further avenues of applications, it is important to understand various properties and the phase transformations of TiO2 polymorphs at ambient conditions. The detailed study on the phase transitions (pressure induced) of the low-pressure polymorphs (rutile, anatase, brookite and columbite) of TiO2 is surprisingly missing in the literature. In view of the above, we have carried out ab-initio calculations on these four polymorphs of TiO2 using full potential linearized augmented plane wave [FP-LAPW] method to study the structural phase transitions and elastic properties. The transition pressures at 0 K among anatase (A), rutile (R), brookite (B) and columbite (C) are found out to be -2.4 GPa (A-B), 5.3 GPa (A-R), 5.7 GPa (A-C), 8.7 GPa (R-C), 10.7 GPa (B-C) and 11.6 GPa (B-R) respectively. The elastic properties at P = 0 GPa are examined through computation of elastic constants for all polymorphs. All the polymorphs are found to be mechanically stable. The anisotropy in shear moduli and directional dependence of Young's modulus are also investigated for all the polymorphs.
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6

Song, Miao, Zexi Lu y Dongsheng Li. "Phase transformations among TiO2 polymorphs". Nanoscale 12, n.º 45 (2020): 23183–90. http://dx.doi.org/10.1039/d0nr06226j.

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7

Nagy, Dávidné, Tamás Firkala, Eszter Drotár, Ágnes Szegedi, Krisztina László y Imre Miklós Szilágyi. "Photocatalytic WO3/TiO2 nanowires: WO3 polymorphs influencing the atomic layer deposition of TiO2". RSC Advances 6, n.º 98 (2016): 95369–77. http://dx.doi.org/10.1039/c6ra18899k.

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8

Shi, Huili, Chaoyun Shi, Zhitong Jia, Long Zhang, Haifeng Wang y Jingbo Chen. "Titanium dioxide-based anode materials for lithium-ion batteries: structure and synthesis". RSC Advances 12, n.º 52 (2022): 33641–52. http://dx.doi.org/10.1039/d2ra05442f.

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In this paper, the structure of three TiO2 polymorphs are introduced, then the preparation and electrochemical properties of TiO2 with different morphologies and the related research on the composite with carbon and other materials are discussed.
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9

Asagoe, Keisuke, Supachai Ngamsinlapasathian, Yoshikazu Suzuki y Susumu Yoshikawa. "Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells". Open Chemistry 5, n.º 2 (1 de junio de 2007): 605–19. http://dx.doi.org/10.2478/s11532-007-0001-4.

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AbstractTiO2 (B) and TiO2 anatase nanowires were prepared at 150 °C for 120 h by a hydrothermal method followed by calcination in air at 400 °C for 2 h and at 700 °C for 2 h for TiO2 (B) and TiO2 anatase, respectively. Although dye-sensitized solar cells (DSC) with fully nanowire electrodes showed a rather low light-to-electricity conversion efficiency of 1.33 % for TiO2 (B) and 2.42% for TiO2 anatase, 10 wt % nanowire-dispersed electrodes in a P-25 TiO2-nanoparticle matrix demonstrated improved efficiency of 6.17 % for TiO2 (B) and 6.53% for TiO2 anatase, these exceeding that of pure P-25 electrodes in this work (η=5.59%). The dominant mechanisms of the improvement at 10 wt% for the two different polymorphs are thought to be different, i.e., a light-scattering and film-thickness increment for the TiO2 (B) system, whereas there is an improved conduction path through the matrix for the TiO2 anatase system.
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10

Gaspar, Miguel, Nuno Grácio, Rute Salgueiro y Mafalda Costa. "Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits". Minerals 12, n.º 10 (30 de septiembre de 2022): 1248. http://dx.doi.org/10.3390/min12101248.

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The Segura mining field, the easternmost segment of the Góis–Panasqueira–Segura tin–tungsten metallogenic belt (north–central Portugal), includes Sn-W quartz veins and Li-Sn aplite-pegmatites, which are believed to be genetically related to Variscan Granites. Sediment geochemistry indicates granite-related Ti-enrichments, locally disturbed by mineralization, suggesting magmatic and metamorphic/metasomatic titaniferous phases. Therefore, Segura alluvial samples and the geochemistry of their TiO2 polymorphs (rutile, anatase, and brookite) were investigated, and their potential as exploration tools for Sn and W deposits was evaluated. The heavy-mineral assemblages proved to be good proxies for bedrock geology, and TiO2 polymorph abundances were found to be suitable indicators of magmatic and/or metasomatic hydrothermal processes. The trace element geochemistry of Segura’s alluvial rutile, anatase, and brookite is highly variable, implying multiple sources and a diversity of mineral-forming processes. The main compositional differences between TiO2 polymorphs are related to intrinsic (structural) factors, and to the P-T-X extrinsic parameters of their forming environments. Anomalous enrichments, up to 9% Nb, 6% Sn and W, 3% Fe, 2% Ta, and 1% V in rutile, and up to 1.8% Fe, 1.7% Ta, 1.2% Nb, 1.1% W 0.5% Sn and V in anatase, were registered. Brookite usually has low trace element content (<0.5%), except for Fe (~1%). HFSE-rich and granitophile-rich rutile is most likely magmatic, forming in extremely differentiated melts, with Sn and W contents enabling the discrimination between Sn-dominant and W-dominant systems. Trace element geochemical distribution maps show pronounced negative Sn (rutile+anatase) and W (rutile) anomalies linked to hydrothermal cassiterite precipitation, as opposed to their hydrothermal alteration halos and to W-dominant cassiterite-free mineralized areas, where primary hydrothermal rutile shows enrichments similar to magmatic rutile. This contribution recognizes that trace element geochemistry of alluvial TiO2 polymorphs can be a robust, cost- and time-effective, exploration tool for Sn(W) and W(Sn) ore deposit systems.
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11

Manuputty, Manoel Y., Jochen A. H. Dreyer, Yuan Sheng, Eric J. Bringley, Maria L. Botero, Jethro Akroyd y Markus Kraft. "Polymorphism of nanocrystalline TiO2 prepared in a stagnation flame: formation of the TiO2-II phase". Chemical Science 10, n.º 5 (2019): 1342–50. http://dx.doi.org/10.1039/c8sc02969e.

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12

Nagy, Dávidné, Tamás Firkala, Eszter Drotár, Ágnes Szegedi, Krisztina László y Imre Miklós Szilágyi. "Correction: Photocatalytic WO3/TiO2 nanowires: WO3 polymorphs influencing the atomic layer deposition of TiO2". RSC Advances 7, n.º 10 (2017): 5979. http://dx.doi.org/10.1039/c7ra90002c.

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Correction for ‘Photocatalytic WO3/TiO2 nanowires: WO3 polymorphs influencing the atomic layer deposition of TiO2’ by Dávidné Nagy et al., RSC Adv., 2016, 6, 95369–95377.
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13

Kobir, Md Mahmudul, Sumaya Tabassum, Shanawaz Ahmed, Sumaiya Islam Sadia y Md Ashraful Alam. "Crystallographic Benchmarking on Diffraction Pattern Profiling of Polymorphs-TiO2 by WPPF for Pigment and Acrylic Paint". Archives of Current Research International 24, n.º 1 (22 de enero de 2024): 62–70. http://dx.doi.org/10.9734/acri/2024/v24i1623.

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At a very low temperature high crystalline phase of TiO2 best-fitted strain anatase was synthesized by peptization which was the prime object of this study. Unresolved parameters were investigated by the X-ray diffraction (XRD) technique employed for lattice parameters, crystallite size, lattice volume, strain, crystal structure, d-spacing and percentage of phase in weight fraction. 54.40 % anatase, 29.10 % brookite and 16.50 % rutile crystalline phase were found by whole powder pattern fitting (WPPF-Rietveld’s refinement) method and lattice volume of anatase 137.150, brookite 267.079 and rutile 62.901 ų as well the crystal strain 0.307, 0.45 and 0.28 % of anatase, brookite and rutile polymorph-TiO2 found respectively. The calculated lattice parameters of the anatase are \(\alpha\)=\(\beta\)=\(\gamma\)= 90.0°; a=b= 3.8056 Å, c= 9.470 Å and predominant (101), (004) and (200) miller indices with diffracted angle (2Ɵ) 25.38, 37.26 and 48.22 observed. The average crystallite size was 7.39 nm which confirmed the formation of nano-crystal-TiO2 due to the highly dispersed on medium. The percentage of strain of the individual polymorphs of TiO2 shows the best fit used for the pigment and acrylic paint.
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14

Lyu, Ying-hai, Feng Wei, Tingting Zhang, Li Luo, Yeye Pan, Xueqi Yang, Hao Yu y Shixue Zhou. "Different antibacterial effect of Ag3PO4/TiO2 heterojunctions and the TiO2 polymorphs". Journal of Alloys and Compounds 876 (septiembre de 2021): 160016. http://dx.doi.org/10.1016/j.jallcom.2021.160016.

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15

Zhang, Maolin, Tiedan Chen y Yunjian Wang. "Insights into TiO2 polymorphs: highly selective synthesis, phase transition, and their polymorph-dependent properties". RSC Advances 7, n.º 83 (2017): 52755–61. http://dx.doi.org/10.1039/c7ra11515f.

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16

Luo, Huixia, Weiwei Xie, Jing Tao, Hiroyuki Inoue, András Gyenis, Jason W. Krizan, Ali Yazdani, Yimei Zhu y Robert Joseph Cava. "Polytypism, polymorphism, and superconductivity in TaSe2−xTex". Proceedings of the National Academy of Sciences 112, n.º 11 (3 de marzo de 2015): E1174—E1180. http://dx.doi.org/10.1073/pnas.1502460112.

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Polymorphism in materials often leads to significantly different physical properties—the rutile and anatase polymorphs of TiO2 are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer-stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivity of TaSe2, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access two stable polytypes and two stable polymorphs in the TaSe2−xTex solid solution and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. The reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present or from a surprising effect of the layer-stacking sequence on electronic properties that are typically expected to be dominated by the properties of a single layer in materials of this kind.
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17

Rajput, Nitul S., Sang-Gook Kim, Jeffrey B. Chou, Jehad Abed, Jaime Viegas y Mustapha Jouiad. "Electron beam induced rapid crystallization of water splitting nanostructures". MRS Advances 1, n.º 13 (21 de diciembre de 2015): 825–30. http://dx.doi.org/10.1557/adv.2015.20.

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ABSTRACTTitanium dioxide (TiO2) loaded with gold (Au) as noble metal, acts as an efficient photocatalyst that has been extensively investigated for water splitting processes. In this paper, we report on the microstructure of atomic layer deposited titanium dioxide and the crystallinity modification of the material using energetic electron beam irradiation. A rapid high-energy electron beam induced crystallization of the nanostructures has been observed in-situ inside a High-Resolution Transmission Electron Microscope (HRTEM). The systematic crystallization of the nanomaterial occurring under the electron beam irradiation (300 KV) indicates the transformation of the near amorphous material into a mixture of two nuances of TiO2 polymorphs, namely rutile and anatase. We believe that this transformation will enhance the efficiency of water splitting process, as the mixed phases of rutile and anatase are known to possess better optical properties than the individual polymorphs of TiO2. This finding may be of particular interest in developing appropriate heat treatment methods for these nanostructures dedicated to water splitting to increase their efficiency.
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18

Bastow, T. J. "47,49Ti NMR in Metals, Inorganics, and Gels". Zeitschrift für Naturforschung A 55, n.º 1-2 (1 de febrero de 2000): 291–97. http://dx.doi.org/10.1515/zna-2000-1-251.

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Some recent progress in solid state 47,49Ti NMR is described and reviewed. The metallic-state work described covers metals such as hep titanium, TiB2 , a number of intermetallics such as TiAl2 and TiAl3· The inorganic work covers the various titanium oxide based materials including the TiO2 polymorphs, anatase, rutile and brookite. The gel work covers the evolution of crystalline titania from gels formed by hydrolysis of titanium isopropoxide. Some complementary data from 17O and 13C NMR and powder X-ray diffraction is also included.
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19

Lumpkin, G. R., M. G. Blackford, K. L. Smith, K. R. Whittle, N. J. Zaluzec, E. A. Ryan y P. Baldo. "Ion irradiation of the TiO2 polymorphs and cassiterite". American Mineralogist 95, n.º 1 (23 de diciembre de 2009): 192–95. http://dx.doi.org/10.2138/am.2010.3329.

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20

Li, Haoguang, Michel Vrinat, Gilles Berhault, Dadong Li, Hong Nie y Pavel Afanasiev. "Hydrothermal synthesis and acidity characterization of TiO2 polymorphs". Materials Research Bulletin 48, n.º 9 (septiembre de 2013): 3374–82. http://dx.doi.org/10.1016/j.materresbull.2013.05.017.

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21

Aravindan, Vanchiappan, Yun-Sung Lee, Rachid Yazami y Srinivasan Madhavi. "TiO2 polymorphs in ‘rocking-chair’ Li-ion batteries". Materials Today 18, n.º 6 (julio de 2015): 345–51. http://dx.doi.org/10.1016/j.mattod.2015.02.015.

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22

Mbae, Jane Kathure y Zipporah Wanjiku Muthui. "Ab initio Investigation of the Structural and Electronic Properties of Alkaline Earth Metal - TiO2 Natural Polymorphs". Advances in Materials Science and Engineering 2022 (27 de marzo de 2022): 1–10. http://dx.doi.org/10.1155/2022/7629651.

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Titanium (IV) oxide (TiO2) has gained much attention due to its application in technologies such as optoelectronics, electronics, sensors, photocatalysts, and sustainable energy generation. However, its optical absorption falls in the ultraviolet part of the electromagnetic spectrum, resulting in a low absorption ratio of solar light. In addition, rapid electron-hole recombination limits its photocatalytic activity. To extend the application range of TiO2, the structural and chemical properties can be modified by adding various dopants to tune its electronic structure for applications within a wider range of the solar energy spectrum and ideally extend towards the visible region, which forms the dominant part of the solar energy spectrum. In this study, the structural and electronic properties of three polymorphs of TiO2 have been studied using density functional theory (DFT) as implemented in the Quantum ESPRESSO simulation package. The exchange-correlation potential has been treated with the generalised gradient approximation (GGA). Cationic substitution with non-toxic alkaline earth metal dopants Mg and Ca has been carried out with the aim of modifying the electronic structure of the polymorphs of TiO2. On 1–4% Mg and Ca cationic substitution, there is a slight expansion of the optimal unit cell volume and modulation of the band gap energy by raising the valence band maximum to higher energies. In addition, dopant inter and intra-band states are observed.
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23

Elmaslmane, A. R., M. B. Watkins y K. P. McKenna. "First-Principles Modeling of Polaron Formation in TiO2 Polymorphs". Journal of Chemical Theory and Computation 14, n.º 7 (6 de junio de 2018): 3740–51. http://dx.doi.org/10.1021/acs.jctc.8b00199.

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24

Vega Poot, Alberto G., David Reyes Coronado y G. Oskam. "Application of Three TiO2 Polymorphs in Photoelectrochemical Solar Cells". ECS Transactions 3, n.º 9 (21 de diciembre de 2019): 233–37. http://dx.doi.org/10.1149/1.2357114.

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25

Kerisit, Sebastien, Kevin M. Rosso, Zhenguo Yang y Jun Liu. "Dynamics of Coupled Lithium/Electron Diffusion in TiO2 Polymorphs". Journal of Physical Chemistry C 113, n.º 49 (17 de noviembre de 2009): 20998–1007. http://dx.doi.org/10.1021/jp9064517.

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26

Triebold, Silke, George Luiz Luvizotto, Raimon Tolosana-Delgado, Thomas Zack y Hilmar von Eynatten. "Discrimination of TiO2 polymorphs in sedimentary and metamorphic rocks". Contributions to Mineralogy and Petrology 161, n.º 4 (13 de julio de 2010): 581–96. http://dx.doi.org/10.1007/s00410-010-0551-x.

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27

Kocot, Karina, Gabriela Dyrda y Rudolf Słota. "The impact of TiO2 modifications on the effectiveness of photocatalytic processes [review]". Acta Innovations, n.º 28 (1 de julio de 2018): 14–19. http://dx.doi.org/10.32933/actainnovations.28.2.

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This paper outlines the recent studies on the application of photocatalysis using semiconductors, with modified titanium dioxide (TiO2) in the process of reducing chemical contamination of surface and ground waters. During the last forty years, an increasing interest in catalysts of this type is noticeable. Hence, a wide range of methods of TiO2 modifications have been proposed so far by using its various polymorphs, composites with metals and non-metals and polymer-coatings or impregnating it with dyes that effectively absorb sunlight.
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28

Johnson, Martha S., Mehmet Ates, Zikri Arslan, Ibrahim O. Farah y Coneliu Bogatu. "Assessment of Crystal Morphology on Uptake, Particle Dissolution, and Toxicity of Nanoscale Titanium Dioxide on Artemia Salina". Journal of Nanotoxicology and Nanomedicine 2, n.º 1 (enero de 2017): 11–27. http://dx.doi.org/10.4018/jnn.2017010102.

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Knowledge of nanomaterial toxicity is critical to avoid adverse effects on human and environment health. In this study, the influences of crystal morphology on physico-chemical and toxic properties of nanoscale TiO2 (n- TiO2) were investigated. Artemia salina were exposed to anatase, rutile and mixture polymorphs of n-TiO2 in seawater. Short-term (24 h) and long-term (96 h) exposures were conducted in 1, 10 and 100 mg/L suspensions of n-TiO2 in the presence and absence of food. Anatase form had highest accumulation followed by mixture and rutile. Presence of food greatly reduced accumulation. n-TiO2 dissolution was not significant in seawater (p<0.05) nor was influenced from crystal structure. Highest toxic effects occurred in 96h exposure in the order of anatase>mixture>rutile. Mortality and oxidative stress levels increased with increasing n-TiO2 concentration and exposure time (p<0.05). Presence of food in the exposure medium alleviated the oxidative stress, indicating deprivation from food could promote toxic effects of n-TiO2 under long-term exposure.
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29

Murad, E. y H. M. Köster. "Determination of the Ti speciation in commercial kaolins by Raman spectroscopy". Clay Minerals 34, n.º 3 (septiembre de 1999): 479–85. http://dx.doi.org/10.1180/000985599546389.

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AbstractRaman spectra of a selection of kaolins with widely varying TiO2 contents revealed the presence of anatase in 17 of 18 samples. A significant positive correlation was observed between the intensity of the main anatase Raman band at ~145 cm-1 and the total TiO2 contents of the kaolins as determined by chemical analysis. No TiO2 modification other than anatase was detected in any of the samples.The determination of the anatase contents in kaolins by XRD becomes increasingly difficult as the concentration of this mineral decreases below ~0.5%. In contrast, anatase and brookite concentrations an order of magnitude lower can still be readily identified by Raman spectroscopy. The specificity and sensitivity of Raman spectroscopy for these TiO2 polymorphs, coupled with the simplicity and rapidity of measurement, therefore make this a viable technique for the routine study of these accessory minerals in kaolins.
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30

Joshi, Bhupendra y Soo Wohn Lee. "Modification of P25 titania in presence of hydrazine for Staphylococcus aureus inactivation". Functional Materials Letters 12, n.º 03 (16 de mayo de 2019): 1950030. http://dx.doi.org/10.1142/s1793604719500309.

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Titania and its polymorphs are one of the most studied semiconductor photocatalysts. Herein, the P25 titania was used as a precursor to modify the phase and structure with microwave-assisted hydrothermal and sonochemical methods in presence of alkaline hydrazine. The outcome results show the cotton ball structure titanate composite phases (nanotubes, nanosheets and nanoparticles) and monoclinic titanate phase (TiO2-B) with microwave-assisted hydrothermal method and sonochemical method, respectively. The nitrogen doping was confirmed by FTIR and DRS in modified TiO2. And some visible light absorption was observed in modified TiO2 due to the nitrogen doping. The composite phase titanate having cotton ball structure was found to be efficient for methicillin-resistant superbug Staphylococcus aureus (MRSA) inactivation. Herein, we also reported the submicron TiO2-B sword like morphology fabricated by sonochemical method for the first time in presence of alkaline hydrazine.
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31

Martínez, Lester, Mónica Benito, Ignasi Mata, Lluís Soler, Elies Molins y Jordi Llorca. "Preparation and photocatalytic activity of Au/TiO2 lyogels for hydrogen production". Sustainable Energy & Fuels 2, n.º 10 (2018): 2284–95. http://dx.doi.org/10.1039/c8se00293b.

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High surface area titania lyogels have been prepared, thermally transformed into TiO2 polymorphs at 400–850 °C, and decorated by ball milling with preformed Au nanoparticles of ca. 2 nm to ensure the same contact points at the metal–support interphase.
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32

Zhu, Tong y Shang-Peng Gao. "The Stability, Electronic Structure, and Optical Property of TiO2 Polymorphs". Journal of Physical Chemistry C 118, n.º 21 (19 de mayo de 2014): 11385–96. http://dx.doi.org/10.1021/jp412462m.

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33

Tosoni, Sergio, Oriol Lamiel-Garcia, Daniel Fernandez Hevia y Francesc Illas. "Theoretical Study of Atomic Fluorine Diffusion through Bulk TiO2 Polymorphs". Journal of Physical Chemistry C 117, n.º 11 (13 de marzo de 2013): 5855–60. http://dx.doi.org/10.1021/jp400474y.

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34

Assadi, M. Hussein N. y Dorian A. H. Hanaor. "Theoretical study on copper's energetics and magnetism in TiO2 polymorphs". Journal of Applied Physics 113, n.º 23 (21 de junio de 2013): 233913. http://dx.doi.org/10.1063/1.4811539.

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35

Leal, J. H., Y. Cantu, D. F. Gonzalez y J. G. Parsons. "Brookite and anatase nanomaterial polymorphs of TiO2 synthesized from TiCl3". Inorganic Chemistry Communications 84 (octubre de 2017): 28–32. http://dx.doi.org/10.1016/j.inoche.2017.07.014.

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36

Kerisit, Sebastien, Kevin M. Rosso, Zhenguo Yang y Jun Liu. "Computer Simulation of the Phase Stabilities of Lithiated TiO2 Polymorphs". Journal of Physical Chemistry C 114, n.º 44 (19 de octubre de 2010): 19096–107. http://dx.doi.org/10.1021/jp103809s.

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37

Ma, X. G., P. Liang, L. Miao, S. W. Bie, C. K. Zhang, L. Xu y J. J. Jiang. "Pressure-induced phase transition and elastic properties of TiO2 polymorphs". physica status solidi (b) 246, n.º 9 (6 de julio de 2009): 2132–39. http://dx.doi.org/10.1002/pssb.200945111.

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38

Kujawa, Weronika, Agnieszka Didyk-Mucha, Ewa Olewnik-Kruszkowska, Magdalena Gierszewska y Anna Rudawska. "Synergistic Effect of Combined Polymorphs Anatase-Rutile Nano-Modified Lightweight Concrete on Photocatalytic Reduction of NOx, Self-Cleaning Performance, and Antimicrobial Properties". Buildings 13, n.º 7 (8 de julio de 2023): 1736. http://dx.doi.org/10.3390/buildings13071736.

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Anatase, one of the polymorphs of titanium dioxide (TiO2), has become the most widely used semiconductor for photocatalytic materials due to its chemical and physical properties. However, researchers have been studying the use of alternative materials (e.g., ZnO, N-doped, and C-doped TiO2) to improve the photocatalytic activity of cementitious materials. In this paper, we propose a modification of lightweight concrete by introducing mixed phases of titanium dioxide—anatase and rutile—to enhance its photocatalytic performance. The efficiency of NOx degradation of nano TiO2-modified concrete, its self-cleaning performance, and its antimicrobial properties were studied. The photocatalytic activity of lightweight concrete without TiO2 and concrete with the addition of anatase, rutile, and anatase-rutile was compared. The results show that modifying the samples by adding a mixture of anatase and rutile (2.5 wt % A + 2.5 wt % R) significantly improved the photocatalytic performance of lightweight concrete.
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39

Xu, Zhongnan, Paul Salvador y John R. Kitchin. "First-Principles Investigation of the Epitaxial Stabilization of Oxide Polymorphs: TiO2 on (Sr,Ba)TiO3". ACS Applied Materials & Interfaces 9, n.º 4 (17 de enero de 2017): 4106–18. http://dx.doi.org/10.1021/acsami.6b11791.

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40

Qi, Xue Mei, Xin Yuan Zhu, Jiang Wu, Yu Wu y Han Cheng Luo. "Sol-Gel Synthesis and Characterization of TiO2-Based Photocatalyst and its Photoactivity Research". Advanced Materials Research 864-867 (diciembre de 2013): 613–16. http://dx.doi.org/10.4028/www.scientific.net/amr.864-867.613.

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The TiO2-based photocatalysts have been synthesized by using sol-gel process and their photocatalytic activities were studied by the degradation of methylene blue (MB). It was shown that the calcination temperature has great influence on the crystalline phase transition of TiO2. For all the samples (Ag-doped and undoped TiO2photocatalysts) calcined at 573K, only anatase phase was observed from XRD diffraction spectra and the intensity of peaks is weak. After the calcined at 773K, a mixture of anatase-rutile phase appeared. The contents of rutile phase were about 85% and77% for undoped and Ag-adopted TiO2photocatalysts.There were only rutile phases for all the TiO2photocatalysts calcined at 973K observed from XRD diffraction spectra. Magnetically stirring time of A solution before added B had no obvious effects on the polymorphs transition of TiO2.
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41

Roursgaard, Martin, Keld A. Jensen, Steen S. Poulsen, Niels-Erik V. Jensen, Lars K. Poulsen, Maria Hammer, Gunnar D. Nielsen y Søren T. Larsen. "Acute and Subchronic Airway Inflammation after Intratracheal Instillation of Quartz and Titanium Dioxide Agglomerates in Mice". Scientific World JOURNAL 11 (2011): 801–25. http://dx.doi.org/10.1100/tsw.2011.67.

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This study investigated the acute and subchronic inflammatory effects of micrometer-size (micro-size) and nanometer-size (nano-size) particles after intratracheal (i.t.) installation in mice. The role of the type of compound, polymorphism, and size of the particles was investigated. Studied compounds were the two micro-size reference quartzes, SRM1878a and DQ12, a micro- and nano-size rutile titanium dioxide (TiO2), a nano-size anatase, and an amorphous TiO2. Particles were administered by a single i.t. instillation in mice at a fixed dose of 5, 50, and 500 μg, respectively. Inflammation was evaluated from the bronchoalveolar lavage fluid (BALF) content of inflammatory cells, the cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), as well as from lung histology. Evaluations were at 24 h (acute effects) and 3 months (subchronic effects) after instillations. Both types of quartz induced a dose-dependent acute increase of neutrophils, IL-6, and total protein in BALF. Limited subchronic inflammation was observed. All types of TiO2induced a dose-dependent acute increase of neutrophils in BALF. In the acute phase, micro- and nano-size rutile and nano-size amorphous TiO2induced elevated levels of IL-6 and total protein in BALF at the highest dose. At the nano-size rutile and amorphous TiO2, subchronic lung inflammation was apparent from a dose-dependent increase in BALF macrophages. Histology showed little inflammation overall. The two types of quartz showed virtually similar inflammatory effects. Nearly similar effects were observed for two sizes of rutile TiO2. Differences were seen between the different polymorphs of nano-size TiO2, with rutile being the most inflammogenic and amorphous being the most potent in regard to acute tissue damage.
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42

Patra, Shanti Gopal y Dan Meyerstein. "On the Mechanism of Heterogeneous Water Oxidation Catalysis: A Theoretical Perspective". Inorganics 10, n.º 11 (26 de octubre de 2022): 182. http://dx.doi.org/10.3390/inorganics10110182.

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Earth abundant transition metal oxides are low-cost promising catalysts for the oxygen evolution reaction (OER). Many transition metal oxides have shown higher OER activity than the noble metal oxides (RuO2 and IrO2). Many experimental and theoretical studies have been performed to understand the mechanism of OER. In this review article we have considered four earth abundant transition metal oxides, namely, titanium oxide (TiO2), manganese oxide/hydroxide (MnOx/MnOOH), cobalt oxide/hydroxide (CoOx/CoOOH), and nickel oxide/hydroxide (NiOx/NiOOH). The OER mechanism on three polymorphs of TiO2: TiO2 rutile (110), anatase (101), and brookite (210) are summarized. It is discussed that the surface peroxo O* intermediates formation required a smaller activation barrier compared to the dangling O* intermediates. Manganese-based oxide material CaMn4O5 is the active site of photosystem II where OER takes place in nature. The commonly known polymorphs of MnO2; α- (tetragonal), β- (tetragonal), and δ-(triclinic) are discussed for their OER activity. The electrochemical activity of electrochemically synthesized induced layer δ-MnO2 (EI-δ-MnO2) materials is discussed in comparison to precious metal oxides (Ir/RuOx). Hydrothermally synthesized α-MnO2 shows higher activity than δ-MnO2. The OER activity of different bulk oxide phases: (a) Mn3O4(001), (b) Mn2O3(110), and (c) MnO2(110) are comparatively discussed. Different crystalline phases of CoOOH and NiOOH are discussed considering different surfaces for the catalytic activity. In some cases, the effects of doping with other metals (e.g., doping of Fe to NiOOH) are discussed.
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43

Chiari-Andréo, Bruna G., Joana Marto, Andreia Ascenso, Carlos Carneiro, Laura Rodríguez, Antonio José Guillot, Teresa M. Garrigues, Helena M. Ribeiro, Ana Melero y Vera Isaac. "The Impact of Titanium Dioxide Type Combined with Coffee Oil Obtained from Coffee Industry Waste on Sunscreen Product Performance". Dermato 1, n.º 1 (21 de junio de 2021): 2–17. http://dx.doi.org/10.3390/dermato1010002.

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(1) Background: Titanium dioxide (TiO2) consists of three polymorphs, including anatase, rutile and brookite. This work aimed to elucidate the influence of rutile and anatase forms in the performance of sunscreens formulated with green coffee oil (GCO) from coffee beans discarded in the agri-food industry. (2) Methods: TiO2 particles were characterized in terms of size and wettability. The sunscreens formulated with GCO were characterized regarding the droplet size, rheology, texture profile analysis (TPA), in vitro Sun Protection Factor and Water Resistance Retention. Topical delivery and permeation studies were performed to confirm caffeine release and skin penetration. (3) Results: Particle size distributions of rutile and anatase TiO2 particles were similar, however, smaller droplets as well as decreased viscosity and increased thixotropy were obtained for anatase TiO2 and GCO formulation compared to rutile form formulations. Notwithstanding, all formulations exhibited linear viscoelastic behavior. Regarding the TPA, a wide range of mechanical properties improved mainly by GCO rather than TiO2 form has been demonstrated. The influence of TiO2 form on UV protection was better evidenced in absence of GCO. The sunscreen formulations containing GCO presented a favorable topical delivery as confirmed by caffeine release and permeation. (4) Conclusions: Both TiO2 forms combined with GCO provided suitable properties including an effective ultraviolet (UV)-light protection.
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44

Zhang, Wei, Yong Tian, Haili He, Li Xu, Wei Li y Dongyuan Zhao. "Recent advances in the synthesis of hierarchically mesoporous TiO2 materials for energy and environmental applications". National Science Review 7, n.º 11 (14 de febrero de 2020): 1702–25. http://dx.doi.org/10.1093/nsr/nwaa021.

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Abstract Because of their low cost, natural abundance, environmental benignity, plentiful polymorphs, good chemical stability and excellent optical properties, TiO2 materials are of great importance in the areas of physics, chemistry and material science. Much effort has been devoted to the synthesis of TiO2 nanomaterials for various applications. Among them, mesoporous TiO2 materials, especially with hierarchically porous structures, show great potential owing to their extraordinarily high surface areas, large pore volumes, tunable pore structures and morphologies, and nanoscale effects. This review aims to provide an overview of the synthesis and applications of hierarchically mesoporous TiO2 materials. In the first section, the general synthetic strategies for hierarchically mesoporous TiO2 materials are reviewed. After that, we summarize the architectures of hierarchically mesoporous TiO2 materials, including nanofibers, nanosheets, microparticles, films, spheres, core-shell and multi-level structures. At the same time, the corresponding mechanisms and the key factors for the controllable synthesis are highlighted. Following this, the applications of hierarchically mesoporous TiO2 materials in terms of energy storage and environmental protection, including photocatalytic degradation of pollutants, photocatalytic fuel generation, photoelectrochemical water splitting, catalyst support, lithium-ion batteries and sodium-ion batteries, are discussed. Finally, we outline the challenges and future directions of research and development in this area.
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45

Ruus, R., A. Kikas, A. Saar, A. Ausmees, E. Nõmmiste, J. Aarik, A. Aidla, T. Uustare y I. Martinson. "Ti 2p and O 1s X-ray absorption of TiO2 polymorphs". Solid State Communications 104, n.º 4 (octubre de 1997): 199–203. http://dx.doi.org/10.1016/s0038-1098(97)00300-1.

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46

Cavaliere, Emanuele, Luca Artiglia, Gian Andrea Rizzi, Luca Gavioli y Gaetano Granozzi. "Structure and thermal stability of fully oxidized TiO2/Pt(111) polymorphs". Surface Science 608 (febrero de 2013): 173–79. http://dx.doi.org/10.1016/j.susc.2012.10.013.

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47

Noto, L. L., O. M. Ntwaeaborwa, J. J. Terblans y H. C. Swart. "Dependence of luminescence properties of CaTiO3:Pr3+ on different TiO2 polymorphs". Powder Technology 256 (abril de 2014): 477–81. http://dx.doi.org/10.1016/j.powtec.2014.01.082.

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48

Tong, Tiezheng, Andrea N. Hill, Marco A. Alsina, Jinsong Wu, Karis Y. Shang, John J. Kelly, Kimberly A. Gray y Jean-François Gaillard. "Spectroscopic Characterization of TiO2 Polymorphs in Wastewater Treatment and Sediment Samples". Environmental Science & Technology Letters 2, n.º 1 (23 de diciembre de 2014): 12–18. http://dx.doi.org/10.1021/ez5004023.

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49

Agirseven, O., D. T. Rivella, J. E. S. Haggerty, P. O. Berry, K. Diffendaffer, A. Patterson, J. Kreb et al. "Crystallization of TiO2 polymorphs from RF-sputtered, amorphous thin-film precursors". AIP Advances 10, n.º 2 (1 de febrero de 2020): 025109. http://dx.doi.org/10.1063/1.5140368.

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50

Amore Bonapasta, Aldo, Francesco Filippone, Giuseppe Mattioli y Paola Alippi. "Oxygen vacancies and OH species in rutile and anatase TiO2 polymorphs". Catalysis Today 144, n.º 1-2 (junio de 2009): 177–82. http://dx.doi.org/10.1016/j.cattod.2009.01.047.

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