Gd3

Gd3 denotes the gadolinium(III) ion, Gd3+, the trivalent form of the lanthanide gadolinium (atomic number 64). In compounds, gadolinium is most stable in the +3 oxidation state. The Gd3+ ion has seven unpaired electrons in the 4f shell, giving it strong paramagnetism, a property that underpins its use in magnetic resonance imaging and certain luminescent materials.

In aqueous solution, Gd3+ forms hydrated complexes such as [Gd(H2O)8]3+. Because free Gd3+ is highly toxic, gadolinium is typically administered as a chelated complex in medical imaging. Chelates, such as those based on DTPA or DOTA ligands, reduce Gd3+ release and clinical toxicity.

Gadolinium-based contrast agents (GBCAs) exploit the T1-relaxivity of Gd3+ to enhance signal on T1-weighted MRI scans. They are available as linear or macrocyclic chelates. Macrocyclic agents tend to be more chemically stable and are associated with lower risk of gadolinium release. Concerns about gadolinium retention and rare adverse events led to dosing guidance and renal function considerations.

Outside medicine, gadolinium compounds, including Gd2O3 and related salts, serve in phosphors, scintillators, and neutron-detection systems because of high neutron cross sections and useful luminescent properties. Gd-containing materials also feature in research on magnetic materials and imaging probes.

Gadolinium occurs naturally in small amounts with other rare earth elements in minerals such as bastnäsite and monazite. Industrial production involves mining, separation by solvent extraction, and conversion to oxides, salts, or metal for use in various applications.