Tantalum . Ta .

Tantalum was discovered in 1802 by A.G Ekeberg in Uppsala, Sweden. Tantalum is a gray, heavy, and very hard metal with platinum-like color when polished. It is malleable, ductile, and can be readily drawn into fine wire with great strength. Tantalum is very resistant to chemical attack and has a high melting point, exceeded only by tungsten and rhenium. Its properties combine well wit other elements to make alloys with great strength, good ductility, and high melting points. Tantalum is used in bone and joint replacement because it is completely immune to body liquids and is nonirritating.

Metal single crystal properties

State	single crystal
Crystal structure	Body centered cubic
Spacegroup	Im3m, cell dimensions/pm [ a=330.29 ]
Production method	Electron beam
Orientation	standard (100), (110), (111) and stepped surfaces like (112) or (115)
Orientation accuracy	< 1 degree, < 0.5 degree or ~ 0.1 degree
Size	diameter 5 - 15 mm
Polishing	as cut, one or two sides polished
Roughness after polishing	~ 0.03 micron
Surface quality	scratch free at 800 times magnification Nomarski interference Zeiss Axiovert 100 microscope
Purity	5 N+
Typical analysis (ppm)	Al < 1, C 80, Co < 3, Cu < 1, Fe 5, H < 10, N 90, O 120, S < 10, Si 25, Ta balance
X-ray diffractions mass	CuKa 166 (μ/ρ) / cm2g-1
Absorption coefficients	CuKa 95.4 (μ/ρ) / cm2g-1
Neutron scattering length	0.691
Thermal neutron capture cross-section	20.6 σa/barns
Density	16.6 g/cm3
Melting point	2995.85 °C / 3268.85 °K
Boiling point	5424.85+/-100 °C / 5697.85 °K
Molar volume	10.87 cm3
Thermal conductivity	57.5 [ 300 K ] WmK-1
Coefficient of linear thermal expansion	6.6 x 10-6 K-1
Electrical resistivity	12.45 x 10-8 [ 298 K ] Ωm
Mass magnetic susceptibility	+1.07 x 10-8 (s) kg-1m3
Number of isotopes (incl. nuclear isomeres)	28
Isotope mass range	159 -> 186