Dysprosium

Dysprosium

Dysprosium is a chemical element with the symbol Dy and atomic number 66. It is a rare earth element with a metallic silver luster. Dysprosium is never found in nature as a free element, though it is found in various minerals, such as xenotime. Naturally occurring dysprosium is composed of 7 isotopes, the most abundant of which is 164Dy.

Dysprosium was first identified in 1886 by Paul Émile Lecoq de Boisbaudran, but was not isolated in pure form until the development of ion exchange techniques in the 1950s. Dysprosium is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility in data storage applications, and as a component of Terfenol-D. Soluble dysprosium salts are mildly toxic, while the insoluble salts are considered non-toxic.

Occurrence

Dysprosium is never encountered as a free element, but is found in many minerals, including xenotime, fergusonite, gadolinite, euxenite, polycrase, blomstrandine, monazite and bastnäsite; often with erbium and holmium or other rare earth elements. Currently, most dysprosium is being obtained from the ion-adsorption clay ores of southern China, and future sources will include the Halls Creek region in Western Australia. In the high-yttrium version of these, dysprosium happens to be the most abundant of the heavy lanthanides, comprising up to 7–8% of the concentrate (as compared to about 65% for yttrium).The concentration of Dy in the Earth crust is about 5.2 mg/kg and in sea water 0.9 ng/L.

Symbol		Dy
Atomic Number		66
Atomic Weight		162.50
Oxidation States		+3
Electronegativity, Pauling		1.23
State at RT		Solid, Metal
Melting Point, K		1685
Boiling Point, K		2835

Appearance and Characteristics

Harmful effects:

Dysprosium is considered to be moderately toxic.

Characteristics:

• Dysprosium is a bright, soft, silvery-white, rare earth metal.
• It tarnishes slowly in air at room temperature and dissolves in both dilute and concentrated acids.
• When present in compounds, dysprosium exists usually in the trivalent state, Dy3+.
• Dysprosium and holmium have the highest magnetic strengths of any elements.
• Dysprosium also has a high thermal neutron absorption cross-section. which makes it an excellent neutron absorber.

Uses of Dysprosium

• Dysprosium is good at absorbing neutrons and so it is used in dysprosium-oxide-nickel cement in control rods in nuclear reactors.
• Terfenol-D (a terbium, iron and dysprosium alloy) expands or contracts in the presence of a magnetic field (magnetostriction) and is used in ships’ sonar systems and in sensors and transducers. Terfenol-D is also used in a speaker called the ‘SoundBug’, which turns any flat surface into a speaker.
• Dysprosium is used in data storage applications such as compact discs and hard discs.
• It is also used in medium source rare-earth lamps (MSRs) in the film industry. Dysprosium iodide is used these lamps to produce an intense white light.
• With vanadium, dysprosium is used in laser materials.