Dysprosium was discovered in 1886. It is used to make control rods in nuclear reactors due to its high magnetic susceptibility. Its characteristics are affected due to the presence of external impurities.
History and Discovery
Erbium ores contained oxides of holmium and thulium. Paul Emile Lecoq de Boisbaudran separated dysprosium from holmium in 1886. He isolated dysprosium by dissolving dysprosium oxides in acid and add ammonia to precipitate its hydroxide. He was successful after more than 30 attempts. Lecoq de Boisbaudran named the element dysprosium, which has been derived from Greek word dysprositos which mean ”hard to get” [1].
Dysprosium
| Periodic Table Classification | Group n/a Period 6 |
|---|---|
| State at 20C | Solid |
| Color | Silvery white |
| Electron Configuration | [Xe] 4f10 6s2 |
| Electron Number | 66 |
| Proton Number | 66 |
| Electron Shell | 2, 8, 18, 28, 8, 2 |
| Density | 8.55 g.cm-3 at 20°C |
| Atomic number | 66 |
| Atomic Mass | 162.50 g.mol -1 |
| Electronegativity according to Pauling | 1.22 |
Occurrence
Dysprosium is not a rare element and is present in the Earth crust is about 5.2 mg/kg and in sea water it is about 0.9 ng/L. Dysprosium do not exist in free form in nature. It is present in many minerals like xenotime (phosphate mineral), fergusonite complex mixture of various oxides), gadolinite (silicate mineral), euxenite (brownish black mineral), polycrase (uranium yttrium oxide complex mixture), blomstrandine (mineral contain many compounds), monazite (reddish brown phosphate) and bastnasite (family of three carbonate –fluoride mineral), sometime it is found in erbium and holmium too. Dysprosium is also obtained as a by-product of yttrium extraction with the help of magnet process which followed ion exchange displacement to obtained dysprosium fluoride or chloride.
Physical Characteristics
Dysprosium is a bright silver lustrous metal. It is soft in nature and can be machined in controlled heating. The presence of small amount of impurities can affect physical properties of dysprosium. At low temperature, it has highest magnetic strength. Dysprosium has ferromagnetic order at 85K, below this temperature it turns into antiferromagnetic state. This unusual transformation cause disordered paramagnetic state at 179 K [2]. Dysprosium has chemical symbol Dy. Its atomic number is 66 and atomic weight is 162.5. Dysprosium melting point is 1407OC and boiling point is 2562OC. Its density at room temperature is about 8.540 g/cm3.
Chemical Characteristics
Dysprosium is chemically active metal. It is slowly tarnished in the air and burn to form dysprosium (lll) oxides. It is electropositive and react rapidly with hot water and slowly with cold water to form dysprosium hydroxide. It reacts vigorously with all halogens above 200OC. Dysprosium dissolves quickly in dilute sulfuric acid and form yellow color solution and the resulting compound dysprosium (III) sulfate is paramagnetic in nature. Dysprosium oxide is also called dysprosia, it is a white powder and is more magnetic in nature as compared to iron oxide. It combines with various non- metal to form binary compounds at high temperature and mostly exist in +3 oxidation state and sometime +2 like DyN, DyP and DyH2 and DyH3. Dysprosium compounds are soluble in water, but dysprosium carbonate tetrahydrate and dysprosium oxalate decahydrate are insoluble in water [3].
Significance and Uses
- Dysprosium in combination with vanadium makes laser material and commercial lighting.
- Dysprosium –cadmium chalcogenides are used for studying chemical reactions.
- In the form of magnet used in electric car motor and wind turbines generators.
- It is used in dosimeter to measure ionizing radiation.
- Dysprosium- iodide and bromide used in high- intensity metal halides lamps (electric lamp produce light by elect arc).
- Dysprosium salts are used in adiabatic demagnetization refrigerators.
- It is also used in phosphorescent materials.
- Dysprosium is used to make high strength Nano-fibers.
- It is used in nuclear control rods for high thermal neutron cross section.
- It is combined with other elements and used as a source of infrared radiations.
- Terfenol-D (terbium, iron and dysprosium alloy) is used in speaker called ‘SoundBug’.
- Dysprosium is used in MSRs (medium source rare earth lamps) in film industry.
Health Hazards
Dysprosium in free or elemental form is non-toxic. However, certain salts of dysprosium that are water soluble are mild toxic, but insoluble salts are non- toxic. It has no biological role. Ingestion of 500 gram or more has proven to be fatal to human life.
Isotopes of Dysprosium
Dysprosium is composed of seven isotopes: 156Dy, 158Dy, 160Dy, 161Dy, 162Dy, 163Dy and 164Dy. They all are stable except 156Dy, which has a half-life of over 1 x 1018 years. Dysprosium has twenty nine radioisotopes having atomic masses 138 to 173. The most stable is 154Dy, that has a half-life of around 3 x 106 years. 159Dy has a half-life of 144.4 days and 138Dy has half-life of 200 ms. It also has 11 metastable isomers having atomic mass range from 140 to 165. 165mDy has half-life of 1.257 minutes and 149m2Dy has 28 ns.
REFERENCES
[1]. https://en.wikipedia.org/wiki/Dysprosium
[2]. Jackson, Mike (2000). “Wherefore Gadolinium? Magnetism of the Rare Earths” (PDF). IRM Quarterly. 10 (3): 6.
[3]. “Chemical reactions of Dysprosium”. Webelements. Retrieved 2012-08-16.