gadolíníum

Gadolíníum, also known as gadolinium (symbol Gd, atomic number 64), is a silvery-white lanthanide metal. It is relatively soft and forms a protective oxide layer in air. Its most common oxidation state is +3, and its compounds, especially Gd3+, are widely studied for their chemical stability and magnetic properties. The element’s magnetic moment is notable among the lanthanides, and it is ferromagnetic below about 20°C, becoming paramagnetic at higher temperatures.

Gadolíníum was discovered in 1880 by Jean Charles Galissard de Marignac from the mineral gadolinite, which was named after the Finnish chemist Johan Gadolin. The name honors the ore rather than the element itself. The element occurs naturally as a mixture of isotopes and is not found free in nature.

Occurrence and production involves rare-earth minerals such as gadolinite, bastnäsite, and monazite. Commercial production concentrates gadolinium through standard rare-earth separation techniques, including solvent extraction and ion exchange. Global supply is dominated by a few producers, with China playing a major role, followed by other producers such as the United States and Australia.

Applications of gadolinium are diverse. In medicine, gadolinium-based contrast agents are used to enhance magnetic resonance imaging (MRI) by shortening relaxation times of tissues. In materials and industry, gadolinium compounds have been used in phosphors (for certain display technologies), and gadolinium is added to some steels and nickel-based alloys to improve specific properties. The element also has a high neutron-capture cross-section, which makes gadolinium useful in some nuclear applications such as control materials and neutron radiography.

Safety and environmental considerations include toxicity of gadolinium ions in unchelated form; when chelated for medical use, toxicity is greatly reduced, but precautions remain, particularly for patients with kidney impairment.