Cerium

Cerium • Lanthanide Rare Earth

Primary XPS region: Ce3d
Overlapping regions: Ba MNN
Binding energies of common chemical states:

Chemical state	Binding energy Ce3d_5/2
Ce(IV) oxide [1]	~882 eV
Ce(III) oxide	~880 eV

Experimental information

Collecting the entire Ce3d region makes data interpretation as straightforward as possible.

Interpretation of XPS spectra

Ce3d region has well separated spin-orbit components (Δ=18.6eV).
- Each spin-orbit component is further split by multiplet splitting.
- For example, the Ce3d spectrum from a pure CeO₂ sample will have six visible components, even though there is only one chemical state.

The most straightforward method for assigning Ce(III) versus Ce(IV) is to compare the complete Ce3d envelope with reference data (see below).
- Ce(III) and Ce(IV) spectra have different multiplet splitting.
- Ce(IV) has peak at 917eV, which is absent in Ce(III) spectrum.

General comments

Common oxidation states : Ce(III) and Ce(IV).

Resources

[1] Beche et al., Sur f . In t er f ace An al. 2008; 40: 264–267

About this element

Symbol: Ce
Date of discovery: 1803
Name origin: Ceres
Appearance: gray
Discoverer: W. von Hisinger
Obtained from: monazite, orthite

Melting point: 1068 K
Boiling point: 3633 K
Density[kg/m³]: 6689
Molar volume: 20.69 × 10^-6 m³/mol
Protons/Electrons: 58
Neutrons: 82
Shell structure: 2,8,18,19,9,2
Electron configuration: [Xe]4f15d16s2
Oxidation state: 3,4
Crystal structure: hexagonal

Cerium, named after the dwarf planet Ceres, is a soft, malleable, and ductile metal. It is likely to ignite when scratched with a knife, and can ignite spontaneously in air at 65°C to 80°C. Its flames are toxic. Water should not be used to put out cerium fires, as its reaction with water produces hydrogen gas. Although known as a rare earth metal, cerium is not rare at all. Available in large quantities, cerium is even more abundant than lead. This element is widely used in making aluminum and heat-resistant alloys.