Titanium dioxide

Titanium dioxide
Names
IUPAC names
Titanium dioxide
Titanium(IV) oxide
Other names
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.033.327
E number E171 (colours)
KEGG
RTECS number XR2775000
UNII
Properties
TiO
2
Molar mass 79.866 g/mol
Appearance White solid
Odor odorless
Density 4.23 g/cm3 (Rutile)

3.78 g/cm3 (Anatase)

Melting point 1,843 °C (3,349 °F; 2,116 K)
Boiling point 2,972 °C (5,382 °F; 3,245 K)
insoluble
Band gap 3.05 eV (rutile)[1]
+5.9·10−6 cm3/mol
2.488 (anatase)
2.583 (brookite)
2.609 (rutile)
Thermochemistry
50 J·mol−1·K−1[2]
−945 kJ·mol−1[2]
Hazards
Safety data sheet ICSC 0338
Not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
Flash point Non-flammable
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 15 mg/m3[3]
REL (Recommended)
 Ca[3]
IDLH (Immediate danger)
 Ca [5000 mg/m3][3]
Related compounds
Other cations
 Zirconium dioxide
Hafnium dioxide
Titanium(II) oxide
Titanium(III) oxide
Titanium(III,IV) oxide
Related compounds
 Titanic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO
2. When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. Generally it is sourced from ilmenite, rutile and anatase. It has a wide range of applications, from paint to sunscreen to food coloring. When used as a food coloring, it has E number E171. World production in 2014 exceeded 9 million metric tons.[4][5][6]

Occurrence

Titanium dioxide occurs in nature as the well-known minerals rutile, anatase and brookite, and additionally as two high pressure forms, a monoclinic baddeleyite-like form and an orthorhombic α-PbO2-like form, both found recently at the Ries crater in Bavaria. One of these is known as akaogiite and should be considered as an extremely rare mineral.[7][8][9] It is mainly sourced from ilmenite ore. This is the most widespread form of titanium dioxide-bearing ore around the world. Rutile is the next most abundant and contains around 98% titanium dioxide in the ore. The metastable anatase and brookite phases convert irreversibly to the equilibrium rutile phase upon heating above temperatures in the range 600–800 °C (1,112–1,472 °F).[10]

Titanium dioxide has eight modifications – in addition to rutile, anatase, and brookite, three metastable phases can be produced synthetically (monoclinic, tetragonal and orthorombic), and five high-pressure forms (α-PbO2-like, baddeleyite-like, cotunnite-like, orthorhombic OI, and cubic phases) also exist:

Form Crystal system Synthesis
rutile tetragonal
anatase tetragonal
brookite orthorhombic
TiO2(B)[11] monoclinic Hydrolysis of K2Ti4O9 followed by heating
TiO2(H), hollandite-like form[12] tetragonal Oxidation of the related potassium titanate bronze, K0.25TiO2
TiO2(R), ramsdellite-like form[13] orthorhombic Oxidation of the related lithium titanate bronze Li0.5TiO2
TiO2(II)-(α-PbO2-like form)[14] orthorhombic
akaogiite (baddeleyite-like form, 7 coordinated Ti)[15] monoclinic
TiO2 -OI[16] orthorhombic
cubic form[17] cubic P > 40 GPa, T > 1600 °C
TiO2 -OII, cotunnite(PbCl2)-like[18] orthorhombic P > 40 GPa, T > 700 °C

The cotunnite-type phase was claimed by L. Dubrovinsky and co-authors to be the hardest known oxide with the Vickers hardness of 38 GPa and the bulk modulus of 431 GPa (i.e. close to diamond's value of 446 GPa) at atmospheric pressure.[18] However, later studies came to different conclusions with much lower values for both the hardness (7–20 GPa, which makes it softer than common oxides like corundum Al2O3 and rutile TiO2)[19] and bulk modulus (~300 GPa).[20][21]

The oxides are commercially important ores of titanium. The metal can also be mined from other minerals such as ilmenite or leucoxene ores, or one of the purest forms, rutile beach sand. Star sapphires and rubies get their asterism from rutile impurities present in them.[22]

Titanium dioxide (B) is found as a mineral in magmatic rocks and hydrothermal veins, as well as weathering rims on perovskite. TiO2 also forms lamellae in other minerals.[23]

Spectral lines from titanium oxide are prominent in class M stars, which are cool enough to allow molecules of this chemical to form.

Production

Evolution of the global production of titanium dioxide according to process.

The production method depends on the feedstock. The most common method for the production of titanium dioxide utilizes the mineral ilmenite. Ilmenite is mixed with sulfuric acid. This reacts to remove the iron oxide group in the ilmenite. The by-product iron(II) sulfate is crystallized and filtered-off to yield only the titanium salt in the digestion solution. This product is called synthetic rutile. This is further processed in a similar way to rutile to give the titanium dioxide product. Synthetic rutile and titanium slags are made especially for titanium dioxide production.[24] The use of ilminite ore usually only produces pigment grade titanium dioxide. Another method for the production of synthetic rutile from ilmenite utilizes the Becher Process.

Rutile is the second most abundant mineral sand. Rutile found in primary rock cannot be extracted hence the deposits containing rutile sand can be mined meaning a reduced availability to the high concentration ore. Crude titanium dioxide (in the form of rutile or synthetic rutile) is purified via converting to titanium tetrachloride in the chloride process. In this process, the crude ore (containing at least 70% TiO2) is reduced with carbon, oxidized with chlorine to give titanium tetrachloride; i.e., carbothermal chlorination. This titanium tetrachloride is distilled, and re-oxidized in a pure oxygen flame or plasma at 1500–2000 K to give pure titanium dioxide while also regenerating chlorine.[25] Aluminium chloride is often added to the process as a rutile promotor; the product is mostly anatase in its absence. The preferred raw material for the chloride process is natural rutile because of its high titanium dioxide content.[26]

One method for the production of titanium dioxide with relevance to nanotechnology is solvothermal Synthesis of titanium dioxide.

Titanium oxide nanotubes, SEM image

Nanotubes

Anatase can be converted by hydrothermal synthesis to delaminated anatase inorganic nanotubes[27] and titanate nanoribbons which are of potential interest as catalytic supports, photocatalysts, thermal [28] and mechanical reinforcement [29] of polymer.

In the synthesis, anatase is mixed with 10 M sodium hydroxide and heated at 130 °C (266 °F) for 72 hours. The reaction product is washed with dilute hydrochloric acid and heated at 400 °C (752 °F) for another 15 hours. The yield of nanotubes is quantitative and the tubes have an outer diameter of 10 to 20 nm and an inner diameter of 5 to 8 nm and have a length of 1 μm. A higher reaction temperature (170 °C) and less reaction volume gives the corresponding nanowires.[30]

Another process for synthesizing TiO
2 nanotubes is through anodization in an electrolytic solution. When anodized in a 0.5 weight percent HF solution for 20 minutes, well-aligned titanium oxide nanotube arrays can be fabricated with an average tube diameter of 60 nm and length of 250 nm. Based on X-ray Diffraction, nanotubes grown through anodization are amorphous.[31] As HF is highly corrosive and harmful chemical, NH4F is now being used as the etching agent in lieu of HF. In a typical synthesis process, a formamide based non aqueous electrolyte is produced containing 0.2M NH4F and 5 vol% of DI water. The anodization process is carried out under 25V at 20oC for 20 hours, in a two electrode electrochemical cell consisting of a highly pure and thoroughly cleaned titanium plate as the anode, a copper plate or platinum wire as the cathode and the aforesaid electrolyte.[32] The as prepared sample is annealed in air at 400oC to get anatase phase.

SEM (top) and TEM (bottom) images of chiral TiO2 nanofibers.[33]

Hollow TiO2 nanofibers can be also prepared by coating carbon nanofibers with titanium(IV) butoxide (Ti(OCH2CH2CH2CH3)4). The product is then heated at 550 °C for several hours in air to remove the carbon core and form TiO2 nanocrystals. When chiral carbon nanofibers are used as templates, the resulting TiO2 fibers are also chiral, i.e., they respond differently to left and right-hand circularly polarized light. Such optical activity is common for organic, but not for inorganic molecules or nanostructures; the latter are preferred for optical applications because of their superior mechanical and thermal stability.[33]

Applications

The most important application areas are paints and varnishes as well as paper and plastics, which account for about 80% of the world's titanium dioxide consumption. Other pigment applications such as printing inks, fibers, rubber, cosmetic products and foodstuffs account for another 8%. The rest is used in other applications, for instance the production of technical pure titanium, glass and glass ceramics, electrical ceramics, catalysts, electric conductors and chemical intermediates.[34] It is also in most red-coloured candy.

Pigment

Titanium dioxide is the most widely used white pigment because of its brightness and very high refractive index, in which it is surpassed only by a few other materials. Approximately 4.6 million tons of pigmentary TiO2 are used annually worldwide, and this number is expected to increase as utilization continues to rise.[35] When deposited as a thin film, its refractive index and colour make it an excellent reflective optical coating for dielectric mirrors and some gemstones like "mystic fire topaz". TiO2 is also an effective opacifier in powder form, where it is employed as a pigment to provide whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, medicines (i.e. pills and tablets) as well as most toothpastes. In paint, it is often referred to offhandedly as "the perfect white", "the whitest white", or other similar terms. Opacity is improved by optimal sizing of the titanium dioxide particles. Some grades of titanium based pigments as used in sparkly paints, plastics, finishes and pearlescent cosmetics are man-made pigments whose particles have two or more layers of various oxides – often titanium dioxide, iron oxide or alumina – in order to have glittering, iridescent and or pearlescent effects similar to crushed mica or guanine-based products. In addition to these effects a limited colour change is possible in certain formulations depending on how and at which angle the finished product is illuminated and the thickness of the oxide layer in the pigment particle; one or more colours appear by reflection while the other tones appear due to interference of the transparent titanium dioxide layers.[36] In some products, the layer of titanium dioxide is grown in conjunction with iron oxide by calcination of titanium salts (sulfates, chlorates) around 800 °C[37] or other industrial deposition methods such as chemical vapour deposition on substrates such as mica platelets or even silicon dioxide crystal platelets of no more than 50 µm in diameter.[38] The iridescent effect in these titanium oxide particles (which are only partly natural) is unlike the opaque effect obtained with usual ground titanium oxide pigment obtained by mining, in which case only a certain diameter of the particle is considered and the effect is due only to scattering.

In ceramic glazes titanium dioxide acts as an opacifier and seeds crystal formation.

Titanium dioxide has been shown statistically to increase skimmed milk's whiteness, increasing skimmed milk's sensory acceptance score.[39]

Titanium dioxide is used to mark the white lines of some tennis courts.[40]

The exterior of the Saturn V rocket was painted with titanium dioxide; this later allowed astronomers to determine that J002E3 was the S-IVB stage from Apollo 12 and not an asteroid.

Sunscreen and UV blocking pigments in the industry

In cosmetic and skin care products, titanium dioxide is used as a pigment, sunscreen and a thickener. It is also used as a tattoo pigment and in styptic pencils. Titanium dioxide is produced in varying particle sizes, oil and water dispersible, and in certain grades for the cosmetic industry.

Titanium dioxide is found in the majority of physical sunscreens because of its high refractive index, its strong UV light absorbing capabilities and its resistance to discolouration under ultraviolet light. This advantage enhances its stability and ability to protect the skin from ultraviolet light. Nano-scaled (particle size of 30–40 nm)[41] titanium dioxide particles are primarily used in sun screen lotion because they scatter visible light less than titanium dioxide pigments while still providing UV protection.[35] Sunscreens designed for infants or people with sensitive skin are often based on titanium dioxide and/or zinc oxide, as these mineral UV blockers are believed to cause less skin irritation than other UV absorbing chemicals.

This pigment is used extensively in plastics and other applications not only as a white pigment or an opacifier but also for its UV resistant properties where the powder disperses the light – unlike organic UV absorbers – and reduces UV damage, due mostly to the extremely high refractive index of the particles.[42] Certain polymers used in coatings for concrete[43] or those used to impregnate concrete as a reinforcement are sometimes charged with titanium white pigment for UV shielding in the construction industry, but it only delays the oxidative photodegradation of the polymer in question, which is said to "chalk" as it flakes off due to lowered impact strength and may crumble after years of exposure in direct sunlight if UV stabilizers have not been included.

Photocatalyst

TiO2 fibers and spirals

Titanium dioxide, particularly in the anatase form, exhibits photocatalytic activity under ultraviolet (UV) irradiation. This photoactivity is reportedly most pronounced at the {001} planes of anatase,[44][45] although the {101} planes are thermodynamically more stable and thus more prominent in most synthesised and natural anatase,[46] as evident by the often observed tetragonal dipyramidal growth habit. Interfaces between rutile and anatase are further considered to improve photocatalytic activity by facilitating charge carrier separation and as a result, biphasic titanium dioxide is often considered to possess enhanced functionality as a photocatalyst.[47] It has been reported that titanium dioxide, when doped with nitrogen ions or doped with metal oxide like tungsten trioxide, exhibits excitation also under visible light.[48] The strong oxidative potential of the positive holes oxidizes water to create hydroxyl radicals. It can also oxidize oxygen or organic materials directly. Hence, in addition to its use as a pigment, titanium dioxide can be added to paints, cements, windows, tiles, or other products for its sterilizing, deodorizing and anti-fouling properties and is used as a hydrolysis catalyst. It is also used in dye-sensitized solar cells, which are a type of chemical solar cell (also known as a Graetzel cell).

The photocatalytic properties of titanium dioxide were discovered by Akira Fujishima in 1967[49] and published in 1972.[50] The process on the surface of the titanium dioxide was called the Honda-Fujishima effect (ja:本多-藤嶋効果).[49] Titanium dioxide, in thin film and nanoparticle form has potential for use in energy production: as a photocatalyst, it can carry out hydrolysis; i.e., break water into hydrogen and oxygen. With the hydrogen collected, it could be used as a fuel. The efficiency of this process can be greatly improved by doping the oxide with carbon.[51] Further efficiency and durability has been obtained by introducing disorder to the lattice structure of the surface layer of titanium dioxide nanocrystals, permitting infrared absorption.[52]

In 1995 Fujishima and his group discovered the superhydrophilicity phenomenon for titanium dioxide coated glass exposed to sun light.[49] This resulted in the development of self-cleaning glass and anti-fogging coatings.

TiO2 incorporated into outdoor building materials, such as paving stones in noxer blocks[53] or paints, can substantially reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides.[54]

A photocatalytic cement that uses titanium dioxide as a primary component, produced by Italcementi Group, was included in Time's Top 50 Inventions of 2008.[55]

Attempts have been made to photocatalytically mineralize pollutants (to convert into CO2 and H2O) in waste water.[56] TiO2 offers great potential as an industrial technology for detoxification or remediation of wastewater due to several factors:[57]

  1. The process uses natural oxygen and sunlight and thus occurs under ambient conditions; it is wavelength selective and is accelerated by UV light.
  2. The photocatalyst is inexpensive, readily available, non-toxic, chemically and mechanically stable, and has a high turnover.
  3. The formation of photocyclized intermediate products, unlike direct photolysis techniques, is avoided.
  4. Oxidation of the substrates to CO2 is complete.
  5. TiO2 can be supported as thin films on suitable reactor substrates, which can be readily separated from treated water.[58]

The photocatalytic destruction of organic matter is also exploited in photocatalytic antimicrobial coatings,[59] which are typically thin films applied to furniture in hospitals and other surfaces susceptible to be contaminated with bacteria, fungi and viruses.

Other applications

Synthetic single crystals of TiO2, ca. 2–3 mm in size, cut from a larger plate.

Health and safety

Titanium dioxide is incompatible with strong reducing agents and strong acids.[71] Violent or incandescent reactions occur with molten metals that are very electropositive, e.g. aluminium, calcium, magnesium, potassium, sodium, zinc and lithium.[72]

Titanium dioxide accounts for 70% of the total production volume of pigments worldwide.[73] It is widely used to provide whiteness and opacity to products such as paints, plastics, papers, inks, foods, and toothpastes. It is also used in cosmetic and skin care products, and it is present in almost every sunblock, where it helps protect the skin from ultraviolet light.

Many sunscreens use nanoparticle titanium dioxide (along with nanoparticle zinc oxide) which, despite reports of potential health risks,[74] is not actually absorbed through the skin.[75] Other effects of titanium dioxide nanoparticles on human health are not well understood.[76] Nevertheless, allergy to topical application has been confirmed.[77]

Titanium dioxide dust, when inhaled, has been classified by the International Agency for Research on Cancer (IARC) as an IARC Group 2B carcinogen, meaning it is possibly carcinogenic to humans.[78] The findings of the IARC are based on the discovery that high concentrations of pigment-grade (powdered) and ultrafine titanium dioxide dust caused respiratory tract cancer in rats exposed by inhalation and intratracheal instillation.[79] The series of biological events or steps that produce the rat lung cancers (e.g. particle deposition, impaired lung clearance, cell injury, fibrosis, mutations and ultimately cancer) have also been seen in people working in dusty environments. Therefore, the observations of cancer in animals were considered, by IARC, as relevant to people doing jobs with exposures to titanium dioxide dust. For example, titanium dioxide production workers may be exposed to high dust concentrations during packing, milling, site cleaning and maintenance, if there are insufficient dust control measures in place. However, the human studies conducted so far do not suggest an association between occupational exposure to titanium dioxide and an increased risk for cancer. The safety of the use of nano-particle sized titanium dioxide, which can penetrate the body and reach internal organs, has been criticized. Studies have also found that titanium dioxide nanoparticles cause inflammatory response and genetic damage in mice.[80][81] The mechanism by which TiO
2 may cause cancer is unclear. Molecular research suggests that cell cytotoxicity due to TiO
2 results from the interaction between TiO
2 nanoparticles and the lysosomal compartment, independently of the known apoptotic signalling pathways.[82]

The body of research regarding the carcinogenicity of different particle sizes of titanium dioxide has led the US National Institute for Occupational Safety and Health to recommend two separate exposure limits. NIOSH recommends that fine TiO
2 particles be set at an exposure limit of 2.4 mg/m3, while ultrafine TiO
2 be set at an exposure limit of 0.3 mg/m3, as time-weighted average concentrations up to 10 hours a day for a 40-hour work week.[83] These recommendations reflect the findings in the research literature that show smaller titanium dioxide particles are more likely to pose carcinogenic risk than the larger titanium dioxide particles.

There is some evidence the rare disease yellow nail syndrome may be caused by titanium, either implanted for medical reasons or through eating various foods containing titanium dioxide.[84]

Dunkin' Donuts in the United States is dropping titanium dioxide from its powdered sugar donuts after public pressure.[85][86][87] However, Andrew Maynard, director of Risk Science Center at the University of Michigan downplayed the supposed danger from use of titanium dioxide in food. He says that the titanium dioxide used by Dunkin’ Brands and many other food producers is not a new material, and it is not a nanomaterial either. Nanoparticles are typically smaller than 100 nanometres in diameter, yet most of the particles in food grade titanium dioxide are much larger.[88]

See also

References

  1. ↑ Nowotny, Janusz (2011). Oxide Semiconductors for Solar Energy Conversion: Titanium Dioxide. CRC Press. p. 156. ISBN 9781439848395.
  2. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
  3. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0617". National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ "Titanium" in 2014 Minerals Yearbook. USGS
  5. ↑ "Mineral Commodity Summaries, 2015" (PDF). U.S. Geological Survey. U.S. Geological Survey 2015.
  6. ↑ "Mineral Commodity Summaries, January 2016" (PDF). U.S. Geological Survey. U.S. Geological Survey 2016.
  7. ↑ El, Goresy; Chen, M; Dubrovinsky, L; Gillet, P; Graup, G (2001). "An ultradense polymorph of rutile with seven-coordinated titanium from the Ries crater.". Science. 293 (5534): 1467–70. PMID 11520981. doi:10.1126/science.1062342.
  8. ↑ El Goresy, Ahmed; Chen, Ming; Gillet, Philippe; Dubrovinsky, Leonid; Graup, GüNther; Ahuja, Rajeev (2001). "A natural shock-induced dense polymorph of rutile with α-PbO2 structure in the suevite from the Ries crater in Germany". Earth and Planetary Science Letters. 192 (4): 485. Bibcode:2001E&PSL.192..485E. doi:10.1016/S0012-821X(01)00480-0.
  9. ↑ Akaogiite. mindat.org
  10. ↑ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. pp. 1117–19. ISBN 0-08-022057-6.
  11. ↑ Marchand R.; Brohan L.; Tournoux M. (1980). "A new form of titanium dioxide and the potassium octatitanate K2Ti8O17". Materials Research Bulletin. 15 (8): 1129–1133. doi:10.1016/0025-5408(80)90076-8.
  12. ↑ Latroche, M; Brohan, L; Marchand, R; Tournoux, (1989). "New hollandite oxides: TiO2(H) and K0.06TiO2". Journal of Solid State Chemistry. 81 (1): 78–82. Bibcode:1989JSSCh..81...78L. doi:10.1016/0022-4596(89)90204-1.
  13. ↑ Akimoto, J.; Gotoh, Y.; Oosawa, Y.; Nonose, N.; Kumagai, T.; Aoki, K.; Takei, H. (1994). "Topotactic Oxidation of Ramsdellite-Type Li0.5TiO2, a New Polymorph of Titanium Dioxide: TiO2(R)". Journal of Solid State Chemistry. 113 (1): 27–36. Bibcode:1994JSSCh.113...27A. doi:10.1006/jssc.1994.1337.
  14. ↑ Simons, P. Y.; Dachille, F. (1967). "The structure of TiO2II, a high-pressure phase of TiO2". Acta Crystallographica. 23 (2): 334–336. doi:10.1107/S0365110X67002713.
  15. ↑ Sato H.; Endo S; Sugiyama M; Kikegawa T; Shimomura O; Kusaba K (1991). "Baddeleyite-Type High-Pressure Phase of TiO2". Science. 251 (4995): 786–788. Bibcode:1991Sci...251..786S. PMID 17775458. doi:10.1126/science.251.4995.786.
  16. ↑ Dubrovinskaia N A; Dubrovinsky L S.; Ahuja R; Prokopenko V B.; Dmitriev V.; Weber H.-P.; Osorio-Guillen J. M.; Johansson B (2001). "Experimental and Theoretical Identification of a New High-Pressure TiO2 Polymorph". Phys. Rev. Lett. 87 (27 Pt 1): 275501. Bibcode:2001PhRvL..87A5501D. PMID 11800890. doi:10.1103/PhysRevLett.87.275501.
  17. ↑ Mattesini M; de Almeida J. S.; Dubrovinsky L.; Dubrovinskaia L; Johansson B.; Ahuja R. (2004). "High-pressure and high-temperature synthesis of the cubic TiO2 polymorph". Phys. Rev. B. 70 (21): 212101. Bibcode:2004PhRvB..70u2101M. doi:10.1103/PhysRevB.70.212101.
  18. 1 2 Dubrovinsky, LS; Dubrovinskaia, NA; Swamy, V; Muscat, J; Harrison, NM; Ahuja, R; Holm, B; Johansson, B (2001). "Materials science: The hardest known oxide". Nature. 410 (6829): 653–654. Bibcode:2001Natur.410..653D. PMID 11287944. doi:10.1038/35070650.
  19. ↑ Oganov A.R.; Lyakhov A.O. (2010). "Towards the theory of hardness of materials". J. of Superhard Materials. 32 (3): 143–147. doi:10.3103/S1063457610030019.
  20. ↑ Al-Khatatbeh, Y.; Lee, K. K. M. & Kiefer, B. (2009). "High-pressure behavior of TiO2 as determined by experiment and theory". Phys. Rev. B. 79 (13): 134114. Bibcode:2009PhRvB..79m4114A. doi:10.1103/PhysRevB.79.134114.
  21. ↑ Nishio-Hamane D.; Shimizu A.; Nakahira R.; Niwa K.; Sano-Furukawa A.; Okada T.; Yagi T.; Kikegawa T. (2010). "The stability and equation of state for the cotunnite phase of TiO2 up to 70 GPa". Phys. Chem. Minerals. 37 (3): 129–136. Bibcode:2010PCM....37..129N. doi:10.1007/s00269-009-0316-0.
  22. ↑ Emsley, John (2001). Nature's Building Blocks: An A–Z Guide to the Elements. Oxford: Oxford University Press. pp.  451–53. ISBN 0-19-850341-5.
  23. ↑ Banfield, J. F., Veblen, D. R., and Smith, D. J. (1991). "The identification of naturally occurring TiO2 (B) by structure determination using high-resolution electron microscopy, image simulation, and distance–least–squares refinement" (PDF). American Mineralogist. 76: 343.
  24. ↑ Winkler, Jochen (2003). Titanium Dioxide. Hannover: Vincentz Network. pp.  30–31. ISBN 3-87870-148-9.
  25. ↑ "Titanium Dioxide Manufacturing Processes". Millennium Inorganic Chemicals. Archived from the original on 14 August 2007. Retrieved 5 September 2007.
  26. ↑ Winkler, Jochen (2003). Titanium Dioxide. Hannover: Vincentz Network. p. 32. ISBN 3-87870-148-9.
  27. ↑ Mogilevsky, Gregory; Chen, Qiang; Kleinhammes, Alfred; Wu, Yue (2008). "The structure of multilayered titania nanotubes based on delaminated anatase". Chemical Physics Letters. 460 (4–6): 517–520. Bibcode:2008CPL...460..517M. doi:10.1016/j.cplett.2008.06.063.
  28. ↑ Harito, Christian; Porras, Ruben; Bavykin, Dmitry V. & Walsh, Frank C. (2017). "Electrospinning of in situ and ex situ synthesized polyimide composites reinforced by titanate nanotubes". Journal of Applied Polymer Science (13): 44641. doi:10.1002/app.44641.
  29. ↑ Harito, Christian; Bavykin, Dmitry V.; Light, Mark E. & Walsh, Frank C. (2017). "Titanate nanotubes and nanosheets as a mechanical reinforcement of water-soluble polyamic acid: Experimental and theoretical studies". Composites Part B: Engineering. 124: 54–63. doi:10.1016/j.compositesb.2017.05.051.
  30. ↑ Armstrong, Graham; Armstrong, A. Robert; Canales, Jesús & Bruce, Peter G. (2005). "Nanotubes with the TiO2-B structure". Chemical Communications (19): 2454–6. PMID 15886768. doi:10.1039/B501883H.
  31. ↑ Gong, Dawei; Grimes, Craig A.; Varghese, Oomman K.; Hu, Wenchong; Singh, R. S.; Chen, Zhi; Dickey, Elizabeth C. (2001). "Titanium oxide nanotube arrays prepared by anodic oxidation". Journal of Materials Research. 16 (12): 3331. Bibcode:2001JMatR..16.3331G. doi:10.1557/JMR.2001.0457.
  32. ↑ Sarkar, A.; Singh, A.K.; Sarkar, D.; Khan, G.G.; Mandal, K. (2014). "TiO2/ZnO core/shell nano-heterostructure arrays as photo-electrodes with enhanced visible light photoelectrochemical performance". RSC Advances. 4 (98): 55629–55634. doi:10.1039/c4ra09456e.
  33. 1 2 Wang, Cui (2015). "Hard-templating of chiral TiO2 nanofibres with electron transition-based optical activity". Science and Technology of Advanced Materials. 16 (5): 054206. Bibcode:2015STAdM..16e4206W. PMC 5070021 Freely accessible. PMID 27877835. doi:10.1088/1468-6996/16/5/054206.
  34. ↑ "Market Study: Titanium Dioxide". Ceresana. Retrieved 21 May 2013.
  35. 1 2 Winkler, Jochen (2003). Titanium Dioxide. Hannover: Vincentz Network. pp.  5. ISBN 3-87870-148-9.
  36. ↑ Koleske, J. V. (1995). Paint and Coating Testing Manual. ASTM International. p. 232. ISBN 978-0-8031-2060-0.
  37. ↑ Koleske, J. V. (1995). Paint and Coating Testing Manual. ASTM International. p. 229. ISBN 978-0-8031-2060-0.
  38. ↑ Pearlescence with Iriodin. pearl-effect.com
  39. ↑ Phillips, Lance G. & Barbano, David M. (1997). "The Influence of Fat Substitutes Based on Protein and Titanium Dioxide on the Sensory Properties of Lowfat Milk". Journal of Dairy Science. 80 (11): 2726. doi:10.3168/jds.S0022-0302(97)76234-9.
  40. ↑ Les, Caren B. (November 2008) Light spells doom for bacteria. Photonics.com
  41. ↑ Dan, Yongbo et al. Measurement of Titanium Dioxide Nanoparticles in Sunscreen using Single Particle ICP-MS. perkinelmer.com
  42. ↑ Polymers, Light and the Science of TiO2, DuPont, pp. 1–2
  43. ↑ Fibre Cement Coating. dowconstructionchemicals.com
  44. ↑ Liang Chu. "Anatase TiO2 Nanoparticles with Exposed {001} Facets for Efficient Dye-Sensitized Solar Cells". scientific reports.
  45. ↑ Li Jianming and Dongsheng Xu (2010). "tetragonal faceted-nanorods of anatase TiO2 single crystals with a large percentage of active {100} facets". Chemical Communications. 46.
  46. ↑ M Hussein N Assadi (2016). "The effects of copper doping on photocatalytic activity at (101) planes of anatase TiO 2: A theoretical study". Applied Surface Science. 387: 682–689.
  47. ↑ "Sand Supported Mixed-Phase TiO2 Photocatalysts for Water Decontamination Applications". Advanced Engineering Materials. 16 (2): 248–254. 2014. doi:10.1002/adem.201300259.
  48. ↑ Kurtoglu M. E.; Longenbach T.; Gogotsi Y. (2011). "Preventing Sodium Poisoning of Photocatalytic TiO2 Films on Glass by Metal Doping". International Journal of Applied Glass Science. 2 (2): 108–116. doi:10.1111/j.2041-1294.2011.00040.x.
  49. 1 2 3 "Discovery and applications of photocatalysis — Creating a comfortable future by making use of light energy". Japan Nanonet Bulletin Issue 44, 12 May 2005.
  50. ↑ Fujishima, Akira; Honda, Kenichi (1972). "Electrochemical Photolysis of Water at a Semiconductor Electrode". Nature. 238 (5358): 37–8. Bibcode:1972Natur.238...37F. PMID 12635268. doi:10.1038/238037a0.
  51. ↑ "Carbon-doped titanium dioxide is an effective photocatalyst". Advanced Ceramics Report. 1 December 2003. This carbon-doped titanium dioxide is highly efficient; under artificial visible light, it breaks down chlorophenol five times more efficiently than the nitrogen-doped version.
  52. ↑ Cheap, Clean Ways to Produce Hydrogen for Use in Fuel Cells? A Dash of Disorder Yields a Very Efficient Photocatalyst. Sciencedaily (28 January 2011)
  53. ↑ Advanced Concrete Pavement materials, National Concrete Pavement Technology Center, Iowa State University, p. 435.
  54. ↑ Hogan, Jenny (4 February 2004) "Smog-busting paint soaks up noxious gases". New Scientist.
  55. ↑ TIME's Best Inventions of 2008. (31 October 2008).
  56. ↑ Winkler, Jochen (2003). Titanium Dioxide. Hannover: Vincentz Network. pp.  115–116. ISBN 3-87870-148-9.
  57. ↑ Konstantinou, Ioannis K; Albanis, Triantafyllos A (2004). "TiO2-assisted photocatalytic degradation of azo dyes in aqueous solution: Kinetic and mechanistic investigations". Applied Catalysis B: Environmental. 49: 1. doi:10.1016/j.apcatb.2003.11.010.
  58. ↑ Hanaor, Dorian A. H.; Sorrell, Charles C. (2014). "Sand Supported Mixed-Phase TiO2 Photocatalysts for Water Decontamination Applications". Advanced Engineering Materials. 16 (2): 248–254. doi:10.1002/adem.201300259.
  59. ↑ Ramsden, Jeremy J. (2015). "Photocatalytic antimicrobial coatings". Nanotechnology Perceptions. 11 (3): 146–168. doi:10.4024/N12RA15A.ntp.15.03.
  60. ↑ Jones, BJ; Vergne, MJ; Bunk, DM; Locascio, LE; Hayes, MA (2007). "Cleavage of Peptides and Proteins Using Light-Generated Radicals from Titanium Dioxide". Anal. Chem. 79 (4): 1327–1332. PMID 17297930. doi:10.1021/ac0613737.
  61. ↑ Harito, Christian; Bavykin, Dmitry V.; Light, Mark E. & Walsh, Frank C. (2017). "Titanate nanotubes and nanosheets as a mechanical reinforcement of water-soluble polyamic acid: Experimental and theoretical studies". Composites Part B: Engineering. 124: 54–63. doi:10.1016/j.compositesb.2017.05.051.
  62. ↑ Harito, Christian; Porras, Ruben; Bavykin, Dmitry V. & Walsh, Frank C. (2017). "Electrospinning of in situ and ex situ synthesized polyimide composites reinforced by titanate nanotubes". Journal of Applied Polymer Science (13): 44641. doi:10.1002/app.44641.
  63. ↑ Lewis, Nathan. "Nanocrystalline TiO2". Research. California Institute of Technology. Archived from the original on 16 April 2009. Retrieved 9 October 2009.
  64. ↑ "Mixed conductors". Max Planck institute for solid state research. Retrieved 16 September 2016.
  65. ↑ Earle, M. D. (1942). "The Electrical Conductivity of Titanium Dioxide". Physical Review. 61 (1–2): 56. Bibcode:1942PhRv...61...56E. doi:10.1103/PhysRev.61.56.
  66. ↑ Paschotta, Rüdiger. "Bragg Mirrors". Encyclopedia of Laser Physics and Technology. RP Photonics. Retrieved 1 May 2009.
  67. ↑ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  68. ↑ Lindström, Henrik; Södergren, Sven; Solbrand, Anita; Rensmo, Håkan; Hjelm, Johan; Hagfeldt, Anders; Lindquist, Sten-Eric (1997-09-01). "Li+ Ion Insertion in TiO2 (Anatase). 2. Voltammetry on Nanoporous Films". The Journal of Physical Chemistry B. 101 (39): 7717–7722. ISSN 1520-6106. doi:10.1021/jp970490q.
  69. ↑ Du, Xianfeng; Wang, Qianwen; Feng, Tianyu; Chen, Xizi; Li, Liang; Li, Long; Meng, Xiangfei; Xiong, Lilong; Sun, Xiaofei (2016-02-04). "One-step Preparation of Nanoarchitectured TiO2 on Porous Al as Integrated Anode for High-performance Lithium-ion Batteries". Scientific Reports. 6. ISSN 2045-2322. PMC 4740746 Freely accessible. PMID 26841711. doi:10.1038/srep20138.
  70. ↑ Su, Dawei; Dou, Shixue; Wang, Guoxiu (2015-09-08). "Anatase TiO2: Better Anode Material Than Amorphous and Rutile Phases of TiO2 for Na-Ion Batteries". Chemistry of Materials. 27 (17): 6022–6029. ISSN 0897-4756. doi:10.1021/acs.chemmater.5b02348.
  71. ↑ Occupational Health Services, Inc. (31 May 1988). "Hazardline" (Electronic Bulletin). New York: Occupational Health Services, Inc.
  72. ↑ Sax, N.I.; Lewis, Richard J., Sr. (2000). Dangerous Properties of Industrial Materials. III (10th ed.). New York: Van Nostrand Reinhold. p. 3279. ISBN 978-0-471-35407-9.
  73. ↑ "Titanium Dioxide Classified as Possibly Carcinogenic to Humans". Canadian Centre for Occupational Health & Safety. August 2006.
  74. ↑ "Nano-tech sunscreen presents potential health risk". ABC News. 18 December 2008. Retrieved 12 April 2010.
  75. ↑ Sadrieh N, Wokovich AM, Gopee NV, et al. (May 2010). "Lack of significant dermal penetration of titanium dioxide from sunscreen formulations containing nano- and submicron-size TiO2 particles". Toxicol. Sci. 115 (1): 156–66. PMC 2855360 Freely accessible. PMID 20156837. doi:10.1093/toxsci/kfq041.
  76. ↑ "Nano World: Nanoparticle toxicity tests". Physorg.com. 5 April 2006. Retrieved 12 April 2010.
  77. ↑ Shaw T, Simpson B, Wilson B, Oostman H, Rainey D, Storrs F (August 2010). "True photoallergy to sunscreens is rare despite popular belief". Dermatitis. 21 (4): 185–98. PMID 20646669.
  78. ↑ "Titanium dioxide" (PDF). 93. International Agency for Research on Cancer. 2006.
  79. ↑ Serpone, Nick; Kutal, Charles (1993). Photosensitive metal-organic systems: mechanistic principles and applications. Columbus, OH: American Chemical Society. ISBN 0-8412-2527-3.
  80. ↑ "Nanoparticles Used in Common Household Items Cause Genetic Damage in Mice". 17 November 2009. Retrieved 17 November 2009.
  81. ↑ Yazdi AS, Guarda G, Riteau N, et al. (November 2010). "Nanoparticles activate the NLR pyrin domain containing 3 (Nlrp3) inflammasome and cause pulmonary inflammation through release of IL-1α and IL-1β". Proc. Natl. Acad. Sci. U.S.A. 107 (45): 19449–54. Bibcode:2010PNAS..10719449Y. PMC 2984140 Freely accessible. PMID 20974980. doi:10.1073/pnas.1008155107.
  82. ↑ Zhu Y, Eaton JW, Li C (2012). "Titanium Dioxide (TiO(2)) Nanoparticles Preferentially Induce Cell Death in Transformed Cells in a Bak/Bax-Independent Fashion". PLoS ONE. 7 (11): e50607. Bibcode:2012PLoSO...750607Z. PMC 3503962 Freely accessible. PMID 23185639. doi:10.1371/journal.pone.0050607.
  83. ↑ National Institute for Occupational Safety and Health. "Current Intelligence Bulletin 63: Occupational Exposure to Titanium Dioxide (NIOSH Publication No. 2011-160)" (PDF). National Institute for Occupational Safety and Health.
  84. ↑ Berglund F, Carlmark B (October 2011). "Titanium, sinusitis, and the yellow nail syndrome". Biol Trace Elem Res. 143 (1): 1–7. PMC 3176400 Freely accessible. PMID 20809268. doi:10.1007/s12011-010-8828-5.
  85. ↑ "Dunkin' Donuts to remove titanium dioxide from donuts". CNN Money. March 2015.
  86. ↑ "Dunkin' Donuts Nixing Controversial Ingredient From Its Doughnuts". Eater. March 2015.
  87. ↑ "Dunkin' to stop using whitening agent". USA TODAY. March 2015.
  88. ↑ Dunkin' Donuts ditches titanium dioxide – but is it actually harmful? The Conversation. March 12, 2015
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.