When a doctor orders an MRI with contrast, gadolinium is what flows into your veins. Well, a carefully engineered compound of it. This silvery-white metal has 7 unpaired electrons that generate a massive magnetic moment. Tissues near it literally glow on MRI scans, revealing tumors and blood vessels in sharp detail.
But medicine is just the beginning. Gadolinium is the only rare earth element that becomes a true magnet at room temperature. And its isotope Gd-157 absorbs neutrons better than any stable nuclide in existence. That makes it essential for controlling chain reactions inside nuclear reactors.
Swiss chemist Jean Charles Galissard de Marignac discovered gadolinium in 1880. The element is named after Finnish mineralogist Johan Gadolin, the first scientist to isolate a rare earth mineral (gadolinite) back in 1794. Earth's crust contains about 6 ppm of gadolinium — less than tin but more than silver. Major deposits are in China, Australia, and India. Global production reaches roughly 7,500 tonnes of gadolinium oxide per year.
Bulk metallic gadolinium is safe for brief contact. However, gadolinium powder is pyrophoric and can spontaneously ignite when heated to 200 degrees C. Free Gd3+ ions are toxic — they block calcium channels in cells, risking seizures and cardiac arrhythmia. In medical contrast agents, gadolinium is securely bound in a chelate complex and cleared by the kidneys within 2 hours. Handling powder requires gloves and proper ventilation.
Gadolinium is the only lanthanide attracted to a magnet at room temperature. Below 20 degrees C it becomes a full ferromagnet with a record magnetic moment of 7.63 Bohr magnetons per atom.
Over 100 million MRI scans are performed worldwide each year. About a third of them require gadolinium contrast — it makes blood vessels and tumors appear bright white on images.
Gadolinium can cool things without electricity! When demagnetized, it drops its own temperature by 5 degrees C. This is the basis of magnetic refrigerators — silent, eco-friendly, and 30% more efficient than conventional ones.
The isotope Gd-157 has a neutron absorption cross-section of 259,000 barns. That is the absolute record among stable nuclides. This is why gadolinium is used in nuclear reactor control rods.
The element is named after Finnish chemist Johan Gadolin, the first scientist to isolate a rare earth mineral back in 1794. Gadolinium itself was not discovered until 86 years later.
Gadolinium has 7 stable isotopes — more than most elements. And one more, Gd-152, is radioactive with a half-life of 108 trillion years — a million times longer than the age of the universe.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
152Gd☢ | 151.919791 | 0.20% | 1.08×10¹⁴ years | α |
154Gd | 153.920866 | 2.18% | stable | — |
155Gd | 154.922622 | 14.80% | stable | — |
156Gd | 155.922123 | 20.47% | stable | — |
157Gd | 156.923960 | 15.65% | stable | — |
158Gd | 157.924104 | 24.84% | stable | — |
160Gd | 159.927054 | 21.86% | stable | — |
Spectroscopic analysis of didymia