Tantalum •Transition Metal

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

Chemical stateBinding energy Ta4f7/2/eV
Ta metal21.8
TaN23.0
Ta2O526.2

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).

crystal structureAbout 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 application.

Application Notes

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