Dysprosium Dy

Discovery

In 1886 Paul-Émile Lecoq de Boisbaudran realised that the oxide then called holmia was not a single substance. Working in Paris, he repeated precipitations with ammonia and oxalic acid dozens of times before he could separate the oxide of a new element.

Pure dysprosium metal had to wait much longer. In the 1950s Frank Spedding's group at the Ames Laboratory in Iowa developed ion-exchange chromatography for separating rare earths on a large scale, and only then could dysprosium and its neighbours be produced in reasonably pure form. Because the lanthanides are chemically so alike, separating them before ion exchange often took thousands of fractional crystallisations. Modern plants use hundreds of stages of continuous solvent extraction instead.

Origin of the name

The name comes from the Greek dysprositos, meaning "hard to get at". Lecoq de Boisbaudran effectively recorded his own frustration with the separation in the element's name.

Main uses

• High-temperature magnets: dysprosium added to neodymium-iron-boron magnets increases their coercivity at elevated temperatures, which is essential in EV traction motors, hybrid cars and wind turbines. Grain-boundary diffusion techniques now place dysprosium only where it is needed, cutting the amount used.
• Magnetostriction: it is a component of Terfenol-D.
• Lighting: dysprosium iodide is added to metal-halide lamps to produce bright, daylight-like white light for film and stage work.
• Nuclear: its neutron absorption has led to dysprosium titanate and similar materials being used in control rods.

Isotopes

Natural dysprosium is made of seven stable isotopes, of which dysprosium-164 is the most abundant at around 28%. Dysprosium-165, made in reactors with a half-life of about 2.3 hours, has been studied for radiation treatment of inflamed joints (radiosynovectomy).

In everyday life

Dysprosium is inside EV motors, wind generators, hard-disk drives and professional lighting. Because production is concentrated in a few places, supply security is a major industrial concern, and recycling of magnets from scrapped products is growing. Dysprosium compounds are generally thought to be of low toxicity, but the metal powder can burn.