Niobium

characteristics
zirconium - niobium - molybdenum
V
Nb
TA

[Kr] 4d 4 5s 1
93
41
Nb

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generally
name, symbol, ordinal number niobium, Nb, 41
series Transition metals
group, period, block 5, 5, D
appearance grey metallically
atomically
atomic mass 92.90638
atomic radius (computed) 145 (198) pm
Kovalenter radius 137 pm
van the Waals radius -
Elektronenkonfiguration [Kr] 4d 4 5 s 1
electrons per Energy level 2, 8, 18, 12, 1
1. Ionization energy 652.1 kJ/mol
2. Ionization energy 1380 kJ/mol
3. Ionization energy 2416 kJ/mol
4. Ionization energy 3700 kJ/mol
5. Ionization energy 4877 kJ/mol
6. Ionization energy 9847 kJ/mol
7. Ionization energy 12100 kJ/mol
physically
state of aggregation (magnetism) firmly (-)
crystal structure cubically body-centered
density (Mohshärte) 8570 kg/m 3 (6)
melting point 2750 K (2477 ° C)
boiling point 5017 K (4744 °C)
molecular volume 10,83 · 10 -6 m 3 /mol
heat of vaporization 696.6 kJ/mol
heat of fusion 30,5 kJ/mol
steam pressure 0.0755 Pa with 2741 K
speed of sound 3480 m/s with 293,15 K
specific thermal capacity 265 j (kg · K)
Electrical conductivity 6,93 · 10 6 S /m
heat conductivity 53.7 w (m · K)
Chemically
oxidation conditions of 3, 5
oxides (basicity) (easily sourly)
normal potential -1.099 V (Nb 3+ + 3e - → Nb)
Elektronegativität of 1.6 (Pauling scale)
isotopes
isotope NH t 1/2 ZM CPU M eV ZP
91 Nb {syn.} 680 A ε 1.253 91 Zr
92 Nb {syn.} 3,47·10 7 A ε
β -
2.006
0.356
92 Zr
92 Mo
93 Nb 100% Nb Meta is stable { syn
. with 52 neutrons} 16.13 A IT 0.031 93 Nb
94 Nb {syn.} 20300 A β - 2.045 94Mo
95 Nb {syn.} 34.975 D β - 0.926 95 Mo
NMR characteristics
93 Nb
nuclear spin 9/2
gamma/ wheel/T 6,539 · 10 7
sensitivity 0.482
Larmorfrequenz with B = “4”, 7 T 48.9 M cycles per second
as far as possible and common,SI-UNITs are used.
If not differently notes,
the indicated data apply with standard conditions.

Niobium (after Niobe - the daughter of the Tantalus -, in the English. often also Columbium) is a chemical element in the periodic system of the elements with the symbolNb and ordinal number 41.

The rarely occurring heavy metal has a grey color and is well forgeable. Niobium can be won from the mineral Niobit. Its main use finds it in the metallurgy for the production of special steel and for the improvement of the weldability.

The discovery of the element in the mineral columbite, today Niobit mentioned, it owes to its names.

Table of contents

history

niobium was discovered 1801 by Charles Hatchett. Hatchettfound niobium in columbite ore, which around 1700 of John Winthrop, which first governor von Connecticut, to England one sent away. It gave the designation of columbites to the element. To center 19. Century it was unsettled whether it itself with niobium and that1802 discovered tantalum around different elements acts. Only 1844 showed the citizen of Berlin professor Heinrich rose that niobium and tantalum acid are different materials.

Not around the work Hatchetts knowing gave rose to the discovered element the name niobium. 1864 succeeded Christian Blomstrand the production of metallic niobium by reduction of niobium chloride with hydrogen in the heat. 1866 confirmed Charles Marignac tantalum as independent element.

Only after 100 years of controversial arguments those put internationally to union OF pure one and Applied Chemistry (IUPAC)1950 niobium as official designation 41. Element of the Periodensystes of the elements firmly. While this linguistic usage within the official range became generally accepted to a large extent, still the designation becomes Columbium within the anglo-saxon language range of many Metallurgen, material offerers and within the private sectorand the abbreviation Cb related.

occurrence

as free element is unknown to niobium, it occurs only in bound form, for example in the following minerals:

  • Niobit (Fe, Mn) (Nb, TA) 2) O 6])
  • Niobit Tantalit [(Fe, Mn) (TA, Nb) 2) O 6]
  • Pyrochlor (NaCaNb 2 O 6 F), and
  • Euxenit [(Y, approx., Ce, U, Th) (Nb, TA, Ti) 2 O 6].

Niobium and tantalum come nearly always verschwistert forwards. Are from economic interest niobium occurrencesin Karbonatiten, in whose residual soils Pyrochlor enriched itself. Brazil and Canada are the main producers of niobhaltigen mineral concentrates. Large ore camps are also in Nigeria, in the democratic Republic of the Congo and in Russia.

characteristics

niobium is a grey shining, duktiles heavy metal. It becomes encrusted after longer storage at air with a bluish resplendent oxidic skin, which works as passive layer (protective layer). It is not attacked by most acids therefore. Only hydrofluoric acid and is called concentrated sulfuric acid corrodesmetallic niobium. In hot alkalis niobium is likewise inconsistant, since they dissolve the passive layer. It is remarkable that niobium is superconducting with 9,2 K still.

The chemical behavior of the niobium is nearly identical that of tantalum, that in the periodic systemdirectly under niobium stands.

A mechanical treatment of niobium must take place because of its inconsistency at air also at ambient temperature under inert gas atmosphere. At temperatures above 200 °C it begins (constantly?) to oxidize. Admit are the Oxidationsstufen -3, -1, 0, +1,+2, +3, +4, +5. As is the case for the vanadium a place in the periodic system is steadiest the stage +5 further above.

use

niobium strip

niobium used as alloying addition for stainless steel, special high-grade steels and non ferrous alloys, there niobium-alloyed itself materials througha increased mechanical firmness distinguish. Kind of such of improved steel are used frequently in the piping construction (pipeline construction). As strong Karbidbildner niobium is zulegiert also in welding filler metals for tying carbon.

Other uses:

  • A low capture cross section for thermal neutrons leads to applications inthe nuclear technology.
  • Production of niobium-stabilized welding electrodes as welding agent for high-grade steels, special high-grade steels and nickel basis alloys.
  • Because of its bluish color it is used for body decoration and for the production by decoration goods.
  • Considerable quantities become as ferrous niobium and nickel niobium in the metallurgical industry the production ofSuperalloys (nickel, cobalt and iron basis alloys) assigned. From this static parts for stationary and flying gas turbines, rocket parts are manufactured and heatproof components for the building of furnaces.
  • Niobium was tested as substitution of more expensive tantalum in the condenser production. (Enter afterwards text Nb as dielectric)

belowfrom 9,3 K pure niobium is superconducting type II. Niobium alloys (with N, O, SN, alga, Ge) belong to their transition temperature Tc between 16 K (N) beside vanadium and technetium to the 3 materials (with 2 pure elements) the type II superconductor are and;18.05 K (SN); Is appropriate for 23.2 K (Ge).

From niobium manufactured superconducting cavities become in particle accelerators (among other things XFEL) assigned.

To the production of high magnetic fields (to approx. 20 T) are used superconducting magnets with wires from niobium-tin and niobium titanium.

safety references

NiobhaltigeConnections are difficult to notice. The element is not considered as toxically, however metallic niobium-deaf eyes and skin irritates. Niobium-deaf is besides easily inflammatory.

A physiological function is unknown.

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