Titanium dioxide in the context of "Titanium"

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⭐ Core Definition: Titanium dioxide

Titanium dioxide, also known as titanium(IV) oxide or titania /tˈtniə/, is the inorganic compound derived from titanium with the chemical formula TiO
2
. When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insoluble in water, although mineral forms can appear black. As a pigment, it has a wide range of applications, including paint, sunscreen, and food coloring. When used as a food coloring, it has E number E171. World production in 2014 exceeded 9 million tonnes. It has been estimated that titanium dioxide is used in two-thirds of all pigments, and pigments based on the oxide have been valued at a price of $13.2 billion.

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👉 Titanium dioxide in the context of Titanium

Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength that is resistant to corrosion in sea water, aqua regia, and chlorine.

Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. The element occurs within a number of minerals, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere; it is found in almost all living things, as well as bodies of water, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll and Hunter processes. The most common compound, titanium dioxide (TiO2), is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and catalysts; and titanium trichloride (TiCl3), which is used as a catalyst in the production of polypropylene.

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Titanium dioxide in the context of White

White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide.

In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France as well as the flag of monarchist France from 1815 to 1830, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek temples and Roman temples were faced with white marble, and beginning in the 18th century, with the advent of neoclassical architecture, white became the most common color of new churches, capitols, and other government buildings, especially in the United States. It was also widely used in 20th century modern architecture as a symbol of modernity and simplicity.

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Titanium dioxide in the context of Nanowire

A nanowire is a nanostructure in the form of a wire with the diameter of the order of a nanometre (10 m). More generally, nanowires can be defined as structures that have a thickness or diameter constrained to tens of nanometers or less and an unconstrained length. At these scales, quantum mechanical effects are important—which coined the term "quantum wires".

Many different types of nanowires exist, including superconducting (e.g. YBCO), metallic (e.g. Ni, Pt, Au, Ag), semiconducting (e.g. silicon nanowires (SiNWs), InP, GaN) and insulating (e.g. SiO2, TiO2).

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Titanium dioxide in the context of Rotary kiln

A rotary kiln is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process. Materials produced using rotary kilns include:

They are also used for roasting a wide variety of sulfide ores prior to metal extraction.

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Titanium dioxide in the context of Anatase

Anatase is a metastable mineral form of titanium dioxide (TiO2) with a tetragonal crystal structure. Although colorless or white when pure, anatase in nature is usually a black solid due to impurities. Three other polymorphs (or mineral forms) of titanium dioxide are known to occur naturally: brookite, akaogiite, and rutile, with rutile being the most common and most stable of the bunch. Anatase is formed at relatively low temperatures and found in minor concentrations in igneous and metamorphic rocks. Glass coated with a thin film of TiO2 shows antifogging and self-cleaning properties under ultraviolet radiation.

Anatase is always found as small, isolated, and sharply developed crystals, and like rutile, it crystallizes in a tetragonal system. Anatase is metastable at all temperatures and pressures, with rutile being the equilibrium polymorph. Nevertheless, anatase is often the first titanium dioxide phase to form in many processes due to its lower surface energy, with a transformation to rutile taking place at elevated temperatures. Although the degree of symmetry is the same for both anatase and rutile phases, there is no relation between the interfacial angles of the two minerals, except in the prism-zone of 45° and 90°. The common octahedral crystal habit of anatase, with four perfect cleavage planes, has an angle over its polar edge of 82°9', whereas rutile octahedra only has a polar edge angle of 56°52½'. The steeper angle gives anatase crystals a longer vertical axis and skinnier appearance than rutile. Additional important differences exist between the physical characters of anatase and rutile. For example, anatase is less hard (5.5–6 vs. 6–6.5 on the Mohs scale) and less dense (specific gravity about 3.9 vs. 4.2) than rutile. Anatase is also optically negative, whereas rutile is optically positive. Anatase has a more strongly adamantine or metallic-adamantine luster than that of rutile as well.

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Titanium dioxide in the context of Ilmenite

Ilmenite is a titanium-iron(II) oxide mineral with the idealized formula FeTiO3. It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used as white pigment in paints, printing inks, fabrics, plastics, paper, sunscreen, food and cosmetics.

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Titanium dioxide in the context of Rutile

Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.

Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high dispersion. Owing to these properties, it is useful for the manufacture of certain optical elements, especially polarization optics, for longer visible and infrared wavelengths up to about 4.5 micrometres. Natural rutile may contain up to 10% iron and significant amounts of niobium and tantalum.

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Titanium dioxide in the context of Titanium tetrachloride

Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is a volatile liquid. Upon contact with humid air, it forms thick clouds of titanium dioxide (TiO2) and hydrochloric acid, a reaction that was formerly exploited for use in smoke machines. It is sometimes referred to as "tickle" or "tickle 4", as a phonetic representation of the symbols of its molecular formula (TiCl4).

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Titanium dioxide in the context of Surface properties of transition metal oxides

Transition metal oxides are compounds composed of oxygen atoms bound to transition metals. They are commonly utilized for their catalytic activity and semiconducting properties. Transition metal oxides are also frequently used as pigments in paints and plastics, most notably titanium dioxide. Transition metal oxides have a wide variety of surface structures which affect the surface energy of these compounds and influence their chemical properties. The relative acidity and basicity of the atoms present on the surface of metal oxides are also affected by the coordination of the metal cation and oxygen anion, which alter the catalytic properties of these compounds. For this reason, structural defects in transition metal oxides greatly influence their catalytic properties. The acidic and basic sites on the surface of metal oxides are commonly characterized via infrared spectroscopy, calorimetry among other techniques. Transition metal oxides can also undergo photo-assisted adsorption and desorption that alter their electrical conductivity. One of the more researched properties of these compounds is their response to electromagnetic radiation, which makes them useful catalysts for redox reactions, isotope exchange and specialized surfaces.

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