Tantalum

Tantalum • Transition Metal

Primary XPS region: Ta4f
Overlapping regions: O2s
Binding energies of common chemical states:

Chemical state	Binding energy Ta4f_7/2
Ta metal	21.8 eV
TaN	23.0 eV
Ta₂O₅	26.2 eV

Experimental information

N/A

Interpretation of XPS spectra

Ta4f region has well separated spin-orbit components (Δmetal=1.92eV).
- Loss feature for Ta metal appears at ~33eV and ~38eV for Ta₂O₅.
- Peaks in the Ta4f region have an asymmetric peak shape for tantalum metal.
- Tantalum compounds, such as the oxide, have symmetric Ta4f peaks.
Use Smart background when sputter profiling films such as Ta₂O₅ on Ta or TaN on Ta.
- Linear or Shirley background which is suitable forTa₂O₅ or TaN will not be suitable for Ta metal.

General comments

Tantalum oxide is widely used as a depth profiling sputter calibration standard because it can be grown with a controlled thickness by electrochemical methods.
Tantalum oxide is reduced by an argon ion beam to form a continuum of oxidation states e.g. Ta₂O₅, Ta₃O₇, Ta₄O₉, etc.
- Use lowest beam energy possible for depth profiling or gas cluster ion source to clean (if available).

About this element

Symbol: Ta
Date of discovery: 1802
Name origin: King Tantalus (Greek mythology)
Appearance: gray-blue
Discoverer: Anders Ekeberg
Obtained from: columbite-tantalite

Melting point: 3290 K
Boiling point: 5731 K
Density[kg/m³]: 16650
Molar volume: 10.85 × 10^-6 m³/mol
Protons/Electrons: 73
Neutrons: 108
Shell structure: 2,8,18,32,11,2
Electron configuration: [Xe]4f145d36s2
Oxidation state: 5,4,3
Crystal structure: cubic

This high-melting point transition metal was separated from niobium in 1802 by A. Ekeberg. When pure, tantalum can be drawn into a fine wire for use as a filament for evaporating metals. Due to its high melting point, ductility, and corrosion resistance, tantalum is often incorporated into a variety of metal alloys for use in chemical process equipment, capacitors and aircraft parts. The metal alloy tantalum carbide graphite is one of the hardest metals known, with a melting point of 3738°C. Tantalum is a non-irritating metal and is immune to body liquids, making it well-suited for use in surgical applications.