| CHEMICAL PROPERTIES | |
| TITANIUM |
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| TANTALUM |
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| properties |
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| standard parts |
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| NIOBIUM |
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Tantalum is found in group 5 of the periodic table of elements. Therefore tantalum shows a chemical behavior similar that of niobium.
In contact with air tantalum forms a thin protective oxide layer which results in a good chemical resistance at room temperature in almost all acids even aqua regia. However, at temperatures above 300 degrees Celsius it reacts with oxygen to the pentoxide (Ta2O5). At very high temperatures it even reacts with nitrogen and carbon (formation of carbides). |
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| OCCURENCE AND PRODUCTION |
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Tantalum is found as ferrous tantalate (Fe,Mn)(TaO3)2 together with niobium. The minerals are named after the respective dominant component niobite (columbite and pyrochlore) or tantalite (tapiolithe).
Firstly, the mixed oxides of niobium and tantalum are processed with a mixture of concentrated hydrofluoric and sulfuric acid. The complex fluorides are subsequently separated by means of liquid-liquid-extraction. The reduction to the metal includes either the electrochemical or metallothermic route or the reduction of the easily accessible oxides with carbon at temperatures between 1700 and 2300 degrees Celsius. Alternatively the ores are processed with chlorine and coke at high temperatures. The chlorides are subject to a fractional distillation and a metallothermic reduction. |
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| PHYSICAL/ MECHANICAL DATA |
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| The figures above are indicative and may deviate from the actual ones. |
| (1)... at 20°C | (2)... annealing period 1h
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| element symbole | Ta | lin. coeff. of thermal expansion (1) | 6.4 * 10-6 m/(m*K) |
| atomic number | 73 | electrical conductivity (1) | 8 * 106 S/m |
| electron configuration | [Xe]4f145d36s2 | specific electric resistance (1) | 0.13 Ω *mm2/m |
| molecular weight | 180.95 g/mol | speed of sound (1) | |
| atomic radius | 1.430 Å | longitudinal wave | 4,100 m/s |
| lattice structure | cubic bc | transversal wave | 2,900 m/s |
| lattice constant | 3.303 Å | electron work function | 4.25 eV |
| density (1) | 16.65 g/cm3 | recrystallization T (2) | 900-1,450°C |
| melting point | 2,996°C | superconductivity | < 4.48 K |
| boiling point | 5,458°C | hardness cold-worked | 180-300 HV10 |
| thermal conductivity (1) | 54 W/(m*K) | hardness recrystallized | 80-100 HV10 |
| specific heat (1) | 0.14 kJ/(kg*K) | young's modulus (1) | 186 GPa |
| | poisson's ratio | 0.34 |
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