Element 64 in our International Year of the Periodic Table series is gadolinium. Gadolinium and its compounds are used in MRI imaging, magnetic refrigerators, and as diamond simulants.

Solutions of gadolinium complexes are used as contrast agents to improve the quality of MRI images. MRI (magnetic resonance imaging) allows the production of detailed images of the inside of the body. MRI contrast agents are either injected or given by mouth to patients, and, as the name suggests, improve the contrast of the resultant image.

Gadolinium is also used in magnetic refrigerators. Magnetic refrigerators work differently to the refrigerator in your kitchen – they cool by using materials whose temperature drops when removed from a magnetic field. Though magnetic refrigerators aren’t yet widely available commercially, their use is increasing. They’re used for some very low-temperature applications, and the first publicly available magnetic refrigerator for food cooling was made available in 2016.

Gadolinium aluminium garnet has been previously used as a diamond substitute in jewellery. This was particularly the case in the 1970s, but drawbacks included its tendency to turn dark brown in sunlight as a result of impurities. Cubic zirconia diamond simulants are much more common today.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.