# Titanium (element)

properties
[ Ar ] 3 d 2 4 s 2
22 Ti
General
Name , symbol , atomic number Titanium, ti, 22
Element category Transition metals
Group , period , block 4 , 4 , d
Appearance silvery metallic
CAS number 7440-32-6
EC number 231-142-3
ECHA InfoCard 100.028.311
Mass fraction of the earth's envelope 0.41%
Atomic
Atomic mass 47.867 (1) u
Atomic radius (calculated) 140 (176) pm
Electron configuration [ Ar ] 3 d 2 4 s 2
1. Ionization energy 6th.828 120 (12) eV 658.81 kJ / mol
2. Ionization energy 13.5755 (25) eV1 309.84 kJ / mol
3. Ionization energy 27.49171 (25) eV2 652.55 kJ / mol
4. Ionization energy 43.26717 (19) eV4 174.65 kJ / mol
5. Ionization energy 99.299 (12) eV9 580.9 kJ / mol
Physically
Physical state firmly
Crystal structure hexagonal (up to 882 ° C, above short)
density 4.50 g / cm 3 (25 ° C )
Mohs hardness 6th
magnetism paramagnetic ( Χ m = 1.8 · 10 −4 )
Melting point 1941 K (1668 ° C)
boiling point 3533 K (3260 ° C)
Molar volume 10.64 · 10 −6 m 3 · mol −1
Heat of evaporation 427 kJ / mol
Heat of fusion 18.7 kJ mol −1
Speed ​​of sound 4140 m s −1 at 293.15 K.
Specific heat capacity 523 J kg −1 K −1
Work function 4.33 eV
Electric conductivity 2.5 · 10 6 A · V −1 · m −1
Thermal conductivity 22 W m −1 K −1
Mechanically
Modulus of elasticity 105 GPa (= 105 kN / mm 2 )
Poisson's number 0.34
Chemically
Oxidation states +2, +3, +4
Normal potential −0.86 V (TiO 2+ + 2 H + + 4 e -
→ Ti + H 2 O)
Electronegativity 1.54 ( Pauling scale )
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP
44 Ti {syn.} 49 a ε 0.268 44 Sc
45 Ti {syn.} 184.8 min ε 2.062 45 Sc
46 Ti 8.0% Stable
47 Ti 7.3% Stable
48 Ti 73.8  % Stable
49 Ti 5.5% Stable
50 Ti 5.4% Stable
51 Ti {syn.} 5.76 min β - 2.471 51 V
52 Ti {syn.} 1.7 min β - 1,973 52 V
For other isotopes see list of isotopes
NMR properties
Spin
quantum
number I
γ in
rad · T −1 · s −1
E r  ( 1 H) f L at
B = 4.7 T
in MHz
47 Ti −5/2 0−1.5105 10 7 2.09 · 10 −3 011.299
49 Ti −7/2 0−1.5109 10 7 3.76 · 10 −3 011.302
safety instructions
GHS labeling of hazardous substances

powder

danger

H and P phrases H: 250-252
P: 210-222-280-235 + 410-422-420
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Titanium is a chemical element with the element symbol Ti and the atomic number 22. It belongs to the transition metals and is in the 4th subgroup (4th  IUPAC group ) or titanium group in the periodic table . The metal is shiny white metallic, has a low density , is ductile , corrosion and temperature resistant .

Today titanium is usually counted among the light metals . With a density of 4.50 g / cm 3 at room temperature, it is the heaviest of these, is close to the limit between light and heavy metals of 5 g / cm 3 that is most commonly used today , as well as the previously common of 4.5 g / cm 3 .

Titanium is one of the ten most common elements in the earth's crust , but is almost exclusively chemically bound as a component of minerals . However, the occurrence of elemental titanium has been proven from several deposits.

## history

Titanium was discovered in 1791 in England by the clergyman and amateur chemist William Gregor in titanium iron . In 1795 the German chemist Heinrich Klaproth also discovered it in rutile ore and gave the element its current name - based on the Greek gods of the titans .

However, it was not until 1831 that Justus von Liebig succeeded in extracting metallic titanium from the ore. 99.9% pure titanium was first produced by Matthew A. Hunter (1878–1961) in 1910 by heating titanium tetrachloride ( titanium (IV) chloride ) with sodium to 700  ° C to 800 ° C in a steel bomb .

It was not until the late 1930s that William Justin Kroll was able to develop a process suitable for the technology, the so-called Kroll process , which was patented in 1940. As a result, the introduction of the large-scale reduction of titanium tetrachloride with magnesium made it possible to develop titanium for commercial applications.

## Occurrence

With a few exceptions (these include elemental titanium and minerals in the form of alloys , intermetallic compounds and sulfides ), titanium only occurs in compounds with oxygen as an oxide in the earth's crust . It is by no means rare, with a content of 0.565%, it is in 9th position in the element abundance in the continental crust. Usually it is only available in low concentrations .

Important minerals are:

The main deposits are in Australia , Scandinavia , North America , the Urals and Malaysia . Deposits were discovered in Paraguay in 2010, but their exploitation is only planned to date.

Meteorites can contain titanium.  Titanium has also been detected in the sun and in stars of the spectral class M. There are also deposits on the Earth's moon . Rock samples from the Apollo 17 moon mission contained up to 12.1% titanium (IV) oxide. There are considerations for asteroid mining .

It is also found in coal ashes, plants and in the human body .

Titanium production in thousands of tons
rank country 2003 2004 2005
1  Australia 1,300 2 110 2 230
2  South Africa 1 070 1 130 1 130
4th  People's Republic of China 400 840 820
5  Norway 380 370 420

## Extraction

Titanium “sponge”, 99.7%, obtained according to the Kroll process
Titan Crystal Bar, 99.995%, made using the Van Arkel de Boer process

Pure titanium hardly occurs in the earth and is extracted from titanium iron ore ( ilmenite ) or rutile . The manufacturing process used is very complex, which is reflected in the high price of titanium. It is 35 times more expensive than common steel alloys and 200 times more expensive than crude steel (as of 2013). In 2008, a ton of titanium sponge cost an average of 12,000 euros.

Production has remained almost unchanged since the Kroll process was discovered . Usually based on ilmenite or rutile , enriched titanium dioxide is converted in the heat with chlorine and carbon to titanium tetrachloride and carbon monoxide . This is followed by liquid magnesium the reduction of titanium tetrachloride to titanium.

${\ displaystyle {\ ce {FeTiO3 + C -> Fe + TiO2 + CO}}}$
${\ displaystyle {\ ce {TiO2 + 2C + 2Cl2 -> TiCl4 + 2CO}}}$
${\ displaystyle {\ ce {TiCl4 + 2Mg -> Ti + 2MgCl2}}}$

In the last reaction step, sodium can be used instead of magnesium .

${\ displaystyle {\ ce {TiCl4 + 4Na -> Ti + 4NaCl}}}$

For the production of machinable alloys must the thus obtained titanium sponge in the vacuum - arc furnace to be remelted.

The largest producer of titanium and titanium alloys is VSMPO-AVISMA with headquarters in Verkhnyaya Salda or Yekaterinburg in the Urals , which has been indirectly owned by the Russian state since September 12, 2006 via the holding Rosoboronexport .

The purest titanium is obtained using the Van Arkel de Boer process .

## properties

Oxidation states of titanium
+2 TiO , TiCl 2
+3 Ti 2 O 3 , TiCl 3 , TiF 3 , TiP
+4 TiO 2 , TiS 2 , TiCl 4 , TiF 4
Pure titanium cylinder
High-purity titanium with an opalescent surface

The tensile strength of titanium alloys is 290 to 1200 N / mm² in the range of structural steel with 310 to 690 N / mm² and alloy steels with 1100 to 1300 N / mm².

Titanium forms an extremely resistant oxidic protective layer ( passivation layer ) in the air , which protects it against many media. Pure titanium is only moderately hard with a value of 6 (according to Mohs ) , but even small amounts of alloy add a high strength and a relatively low density. This makes titanium alloys particularly suitable for applications that require high corrosion resistance, strength and low weight . Above a temperature of 400 ° C, the strength properties decrease quickly. High-purity titanium is ductile , which means that it can be plastically deformed. At higher temperatures, it becomes brittle very quickly due to the absorption of oxygen , nitrogen and hydrogen and thus loses its easy malleability.

The high reactivity of titanium with many media at elevated temperatures or elevated pressure should also be noted if the passivation layer cannot withstand these conditions. Here the speed of reaction can increase up to the point of explosion . In pure oxygen at 25 ° C and 25 bar, titanium burns completely from a freshly cut edge to form titanium dioxide . Despite passivation layer reacts at temperatures above 880 ° C with oxygen at temperatures from 550 ° C with chlorine . Titanium also reacts (“burns”) with pure nitrogen . During machining , heat is generated and pure argon can be used as a protective gas . When deforming titanium, work hardening occurs similarly to stainless steel . The use of a liquid coolant can be useful in order to protect the tool cutting edge.

Titanium is resistant to dilute sulfuric acid , hydrochloric acid , chloride-containing solutions, cold nitric acid , alkalis such as sodium hydroxide and most organic acids , but slowly dissolves in concentrated sulfuric acid to form violet titanium sulfate . Due to the risk of explosion , the operating conditions must be strictly observed when using chlorine gas.

The mechanical properties and the corrosive behavior can be significantly improved by adding mostly minor alloys of aluminum , vanadium , manganese , molybdenum , palladium , copper , zirconium and tin .

Below a temperature of 0.4 K titanium is superconducting . Below 880 ° C, titanium is present in a hexagonal closest packing of spheres . Above 880 ° C forms a body-centered cubic lattice structure from.

Titanium in powder form is pyrophoric, meaning it can ignite spontaneously. Even at room temperature it reacts with the surrounding air, the heat of reaction heats the material until a smoking flame forms , accelerating the reaction .

The readiness to ignite depends very much on the grain size and the degree of distribution. The metal in compact form is not flammable. However, at higher temperatures it easily absorbs oxygen, nitrogen and hydrogen, which causes embrittlement and an increase in hardness.

Titanium can adopt oxidation states 2, 3 and 4. Only the compounds with the oxidation state 4 are stable.

## Coloring

Titanium can be designed in color by specifically creating an oxide layer by means of anodizing . The color is achieved by refraction of light on layers of different thicknesses and not by color pigments, cf. Thin film interference . A gold color is obtained at 10-25 nm, purple at 25-40 nm, dark blue at 40-50 nm, light blue at 50-80 nm, yellow at 80-120 nm, orange at 120-150 nm and orange at 150-180 nm purple, at 180-210 nm green.

## Titanium alloys

Titanium alloys are often characterized with grades 1 to 39 according to the US American standard ASTM . Grade 1 to 4 denotes pure titanium of various degrees of purity .

Pure titanium has the material number 3.7034; the economically most important material used (also for turbocharger blades) Ti-6Al-4V (" Ti64 "; 6% aluminum, 4% vanadium, ASTM: Grade  5) has the number 3.7165 (industrial application) and 3.7164 (aerospace application).

Other important titanium alloys that are mainly used in the aerospace industry:

designation Alloy composition (in%) Young's modulus in GPa Density in g cm −3
Ti6246 Ti-6Al-2Sn-4Zr-6Mo 125.4 4.51
Ti6242 Ti-6Al-2Sn-4Zr-2Mo 4.50

Titanium is difficult to form due to its hexagonal crystal structure. In the manufacture of titanium sheet from titanium blocks, rolling accounts for around 50% of the total cost of the product.

Nitinol (nickel-titanium) is a shape memory alloy and is highly pseudo-elastic , which is why it is used for glasses frames and extirpation needles .

## use

Titanium compressor blades of a jet engine
Wrist watch with a titanium bracelet or case

Titanium is mainly used as a micro-alloy component for steel. It gives steel high toughness, strength and ductility even in concentrations of 0.01–0.1 percent by mass . In stainless steels, titanium prevents intergranular corrosion .

Titanium-based alloys are very expensive at around € 25 / kg. They are therefore only used for the highest requirements:

Protective equipment military and police:

Applications in sea water and media containing chloride:

Outdoor and sporting goods:

• For high-quality bicycles in conjunction with aluminum and vanadium as frame material and for screws
• (Diving) knives with titanium or titanium alloy blades , as well as cutlery
• As tent pegs (high strength despite low weight)
• For golf clubs as a club head. About 25% of the titanium is used for this.
• For tennis rackets in the frame
• In stick shooting as an extremely stable stick with the ice stick stick
• As a particularly light ice screw for mountaineering
• As a lacrosse shaft for greater strength and lower weight
• As a firm leader when fishing for predatory fish with sharp teeth

Use in the form of compounds:

The titanium-sapphire crystal is the bright red glowing object in the left half of the picture. The green light is from the pump laser
• Manufacture of soft artificial gemstones
• Titanium-doped sapphire single crystals serve as the active medium in the titanium-sapphire laser for ultra-short pulses in the femtosecond range
• As titanium tetrachloride for the production of glass mirrors and artificial fog
• Formation of intermetallic phases (Ni 3 Ti) in highly heat-resistant nickel alloys
• Superconducting niobium- titanium alloys (e.g. as superconducting cables in electromagnets from HERA at DESY )
• In pyrotechnics
• As titanium nitride for coatings on indexable inserts and milling cutters in manufacturing technology

Compounds of titanium with boron , carbon or nitrogen are used as hard materials. Titanium compounds are also used to manufacture cermets , special types of hard metal .

Most of the SR-71 is made of titanium

Construction parts:

• Wear parts in soldering systems , direct contact with electric solder up to 500 ° C
• Springs in vehicle chassis
• In aircraft and spaceships for particularly stressed parts that still have to be light (e.g. outer skin at supersonic speeds, compressor blades and other engine parts, landing gear)
• In steam turbines for the most heavily loaded blades of the low-pressure part
• In the armor: some submarine types in the Soviet Union had pressure hulls made of a titanium alloy (e.g. Mike class , Alfa class , Papa class or Sierra class ). In addition, titanium is used more often in military aviation than in civil aviation. As a result, at the height of Soviet armaments production, much of the world's titanium manufacture and use took place in the Soviet Union.
• Because of its low density in the manufacture of level indicators and floats
• Liner for carbon fiber wrapped pressure vessels (type III). In order to ensure complete incineration / atomization when space satellites re-enter, however, the lower- melting aluminum is advantageous.

Medicine:

Electronics:

• In 2002 Nokia launched the 8910 mobile phone and a year later the 8910i mobile phone with a titanium case.
• In April 2002 Apple Inc. brought the " PowerBook G4 Titanium " notebook onto the market. Large parts of the case were made of titanium, and the 15.2-screen version of the notebook was 1 ″ and weighed only 2.4 kg.
• In September 2019, Apple Inc. brought the 5th generation Apple WatchApple Watch ” in a titanium edition onto the market. The 40 millimeter version weighs 35.1 grams (titanium) and 40.6 grams (steel). The 44-millimeter version weighs 41.7 grams (titanium) and 47.8 grams (steel).
• Some notebooks of the ThinkPad series from Lenovo (formerly IBM) have a titanium-reinforced plastic housing or a housing frame made of a titanium-magnesium composite.

Electronic cigarettes:

• Titanium wire is used here as a heating coil, as the electrical resistance of titanium changes measurably depending on the temperature. On this basis, the latest electric battery mods simulate a temperature control of the winding (heating coil) in order to prevent temperature damage to the wick material (organic wadding). In addition to nickel-200 wires and V2A steel wires, titanium is gaining popularity in the scene for this purpose.

Other areas of application:

## proof

An ice bath containing hydrogen peroxide after adding the sample boiled in concentrated sulfuric acid ${\ displaystyle [Ti (O_ {2}) \ cdot aq] ^ {2+}}$

With hydrogen peroxide, TiO 2+ forms a characteristic yellow-orange complex (triaquohydroxooxotitan (IV) complex), which is also suitable for photospectrometric detection. The sample is boiled with an excess of concentrated sulfuric acid and poured into an ice bath with hydrogen peroxide. With a loud hissing sound, the ice bath turns yellow-orange.

${\ displaystyle [Ti (OH) _ {2} (H_ {2} O) _ {4}] ^ {2 +} + H_ {2} O_ {2} \ rightarrow \ underbrace {[Ti (O_ {2} ) \ cdot aq] ^ {2+}} _ {orange} + 6H_ {2} O}$

Due to the great similarity in color, this evidence is also known colloquially as the " Tequila Sunrise evidence".

## Norms

Titanium and titanium alloys are standardized in:

• DIN 17850, edition: 1990-11 titanium; chemical composition
• ASTM B 348: Standard Specification for Titanium and Titanium Alloy, Bars and Billets
• ASTM B 265: Standard Specification for Titanium and Titanium Alloy, Sheets and Plates
• ASTM F 67: Standard Specification for Unalloyed Titanium, for Surgical Implant Applications
• ASTM F 136: Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications
• ASTM B 338: Standard Specification for Seamless and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat Exchangers
• ASTM B 337: Specification for Seamless and Welded Titanium and Titanium Alloy Pipe
• ASTM F2885-11: Standard Specification for Metal Injection Molded Titanium-6Aluminum-4Vanadium Components for Surgical Implant Applications

## safety instructions

Titanium is flammable as a powder, and compactly harmless. Most titanium salts are considered harmless. Inconsistent compounds such as titanium trichloride are highly corrosive as they form hydrochloric acid with just traces of water.

Titanium tetrachloride is used in smoke grenades ; it reacts with the humidity and forms a white smoke from titanium dioxide, as well as hydrochloric acid mist.

The biological disadvantages of titanium in the human body are currently unknown. The hip joints or jaw implants previously made of titanium did not trigger any allergies, unlike nickel.

While metallic titanium is only reserved for demanding technical applications due to its high manufacturing costs , the relatively inexpensive and non-toxic color pigment titanium dioxide has become a companion in everyday life. Practically all white plastics and paints today and also food colors contain titanium dioxide (it can be found in food as E 171 ). But titanium compounds are also used in electrical engineering and materials technology and, recently, in the manufacture of high-performance batteries for vehicle propulsion ( lithium titanate batteries ).

### Oxides

The most important titanium oxide is titanium (IV) oxide (TiO 2 ), which is present in three important polymorphs : anatase , brookite and rutile . They adopt polymeric structures in which titanium is surrounded by six oxide ligands. A variety of reduced oxides ( suboxides ) of titanium are known, mainly reduced stoichiometries of titanium (IV) oxide obtained by atmospheric plasma spraying . Ti 3 O 5 is a purple-red semiconductor that is produced by reducing titanium (IV) oxide with hydrogen at high temperatures and is used industrially when surfaces have to be vaporized with titanium (IV) oxide : It evaporates as pure titanium ( II) oxide , while titanium (IV) oxide evaporates as a mixture of oxides and deposits coatings with a variable refractive index . It is also known titanium (III) oxide with the corundum structure, and titanium (II) oxide with the sodium chloride structure.

### Sulphides

Titanium (IV) sulfide forms crystals that have a layered structure, namely the cadmium iodide structure. It can be used as an electrode material in lithium batteries or lithium-ion accumulators , whereby the low atomic weight of titanium is an advantage.

### Titanates

Titanates are used as a ceramic material. Many, for example lead titanate , lead zirconate titanate , barium titanate and strontium titanate , form ion crystals with a perovskite structure of space group Pm 3 m (space group no. 221) with ferroelectric properties. Barium titanate has piezoelectric properties and is used as a transducer in the conversion of sound and electricity . As a Lewis acid, tetraisopropyl orthotitanate is an important catalyst for esterification and transesterification reactions and for Sharpless epoxidations and is the starting material for ultra-thin titanium (IV) oxide layers and nanoparticles .

### Halides

Depending on the oxidation state, titanium forms different types of halides . Titanium (IV) chloride is a colorless volatile liquid which hydrolyzes in air with spectacular white cloud emissions . In the Kroll process , it is produced when titanium ores are converted into titanium (IV) oxide . It is used as a Lewis acid in organic chemistry , for example in the Mukaiyama aldol reaction . When crystal bar process is titanium (IV) iodide produced for the production of high purity titanium metal.

Titanium (III) fluoride , titanium (III) chloride , titanium (III) bromide and titanium (III) iodide form different crystal structures . Titanium (III) chloride occurs in four different structures that have different chemical properties.

Titanium (II) chloride , titanium (II) bromide and titanium (II) iodide are crystalline solids and have a trigonal crystal structure of the cadmium (II) iodide type ( polytype 2H) with the space group P 3 m 1 (space groups No. 164) .

### Other inorganic compounds

Titanium nitride forms golden yellow crystals . Titanium carbide is a gray powder. Both have similar properties: They form a cubic lattice, are extremely hard , have high thermodynamic stability, high thermal and electrical conductivity and a very high melting point and boiling point . Titanium boride is used together with boron nitride as a material for evaporation boats. To a lesser extent, it is used as test material for cathodes in aluminum fused-flow electrolysis cells and as armor material, as well as a substitute for diamond dust and for coatings . By incorporation of titanium boride particles in aluminum , the properties of aluminum can be improved.

Titanyl sulphate is used as a detection reagent for hydrogen peroxide and titanium, since the intense orange-yellow colored peroxotitanyl ion (TiO 2 ) 2+ is formed when it is present . This proof is very sensitive and traces of hydrogen peroxide can already be detected. It is also produced as an intermediate product in the sulphate process for the production of titanium (IV) oxide .

Titanium dihydride is a powder with a metallic sheen in its pure form . Otherwise it is light gray and may have a surface tinted blue or yellow by traces of oxygen or nitrogen . It is used as a blowing agent in the production of metal foams. It is mixed with metal powder and the mixture is then heated to almost the melting point of the metal . The titanium dihydride releases hydrogen bubbles, which creates metal foam.

### Organometallic complexes

Titanocene dichloride with the semi-structural formula [Ti (Cp) 2 Cl 2 ] or also [Ti (C 5 H 5 ) 2 Cl 2 ], is a metallocene of titanium, i.e. an organometallic compound with aromatic ring systems . It can be obtained from titanium (IV) chloride and cyclopentadiene .

## literature

Commons : Titan (Element)  - album containing pictures, videos and audio files
Wiktionary: Titan  - explanations of meanings, origins of words, synonyms, translations

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