The Element Erbium
Erbium is a silver-colored metal that belongs to the lanthanide group of the periodic table. This metal is bright, shiny, soft, and ductile. Unlike other rare-earth metals, erbium is stable when exposed to air, as it oxidizes slowly when combined with oxygen. Pure erbium itself may not be that distinguishable from other silver metals, but its pretty, pink salts certainly are. Let’s further explore this element.
Cool Facts About Erbium
- Erbium is a rare-earth metal. Contrary to its name, it is actually the 45th most abundant element in the Earth’s crust.
- A small town in Sweden called Ytterby inspired the naming of erbium. There are other elements whose names also come from Ytterby: terbium, yttrium, and ytterbium.
- Er3+ glows bright pink under fluorescent light. This makes these ions ideal for optical applications.
- Erbium compounds have wide applications and even make computer monitors.
- The world produces about 500 tons of erbium annually.
Erbium is a Lanthanide
The lanthanide group consists of fifteen chemical elements, which all have one valence electron in their 5d orbital shell. While lanthanides are generally reactive, erbium differs. It oxidizes slowly and is stable in oxygen. Being a lanthanide, erbium has several important properties, including being a strong reducing agent, a soft metal, and having high melting and boiling points of 1529°C and 2868°C, respectively. Notably, out of all the lanthanides, erbium has one of the weakest nuclear spins, while the rest are strongly paramagnetic.
Isotopes of Erbium
To start, what is an isotope? Isotopes are atoms of a chemical element that differ in the number of neutrons. While they behave similarly chemically, they have physical differences. Currently, we know of thirty-one isotopes, including both stable and radioactive. The six stable isotopes are 162Er, 164Er, 166Er,167Er, 168Er, and 170Er. Out of these six, 166Er is the most abundant, with an abundance of 33.6%. However, 168Er is the only one with significant real-world applications. It produces 169Er, which can help treat rheumatoid arthritis by helping to heal damaged cartilage.
Among the thirteen radioactive isotopes, 169Er is the most stable, having a half-life of 9.4 days. On the other hand, the majority of the isotopes have half-lives shorter than four minutes. These radioactive isotopes form when small particles, like neutrons, fire at the element’s atoms and remain there. Moreover, they emit radiation when they break apart. All of erbium’s isotopes share the characteristic of being good neutron absorbers, making them popular in the manufacturing of nuclear reactor control rods.
Erbium’s Applications in Today’s World
Erbium yttrium aluminum garnet (YAG) lasers are solid-state lasers. You may be familiar with them if you have ever gone through laser treatment for the removal of acne scars, moles, tattoos, or warts. These lasers emit wavelengths of light that create heat to destroy diseased cells. According to “Why Erbium: YAH Lasers Offer Superior Treatments Than CO2 Lasers”, erbium YAG laser treatments are safer for the skin because it is less invasive and painful. Compared to CO2 lasers that have a wavelength of 10,600 nm, erbium YAG lasers emit 2940 nm. With this wavelength, erbium YAG lasers can rapidly vaporize water in the skin without causing much heat damage.
Pure vanadium metal is a semi-hard metal that can be a little difficult to work with because it is not very flexible. Therefore, erbium is a common additive to vanadium alloys, which increases ductility and workability. In addition, erbium is an additive to nickel alloys, which have great resistance to high liquid-helium temperatures. This makes it ideal for the manufacture of cryocoolers and photographic filters.
Erbium-doped amplifiers are important for long-range optical fiber-optic communications. What is this? Fiber-optic communication is a way of transmitting information over long distances via optical fibers. Optical fibers are flexible, thin strands of glass or plastic that carry light from one end of the fiber to the other. Through fiber-optic communications, we can send voice messages and videos over a long distance and are able to use the internet. Adding erbium to the optical fibers amplifies light and compensates for the loss of any optical fiber in long-distance communication. Essentially, erbium is a booster that increases the power in the transmission line.
Erbium in Glass
Like antimony and gallium, the element erbium can absorb infrared light. When added to glass, the glass gains the ability to also absorb infrared light. Therefore, laser safety glasses often contain erbium. These will work to protect the eyes from laser beams and radiation. Compounds of erbium, such as erbium oxide are coloring agents because of their pink color. Aside from creating safety googles, this element produces pretty products. When added to glass or porcelain, it creates a lovely, pink tint that may be seen in cheap jewelry.
History of Erbium
Carl-Gustav Mosander, both a surgeon and chemist from Sweden, “discovered” elemental erbium in 1843. He obtained a gadolinite mineral sample, and upon analyzing it, extracted yttria, which he divided into three different materials: yttria, erbia, and terbia. However, because of their similar properties, erbia and terbia were often confused for each other. Eventually, terbia was renamed erbia, and erbia was renamed terbia in 1860 and 1877, respectively. While Mosander is known as the founder of erbium, he technically only discovered erbia, a compound of erbium.
In 1905, French chemist George Urbain and American chemist Charles James obtained pure samples of erbia. Pure erbium metal was not obtained until 1943. Two workers, Wilhelm Klemm and Heinrich Bommer, reduced anhydrous erbium chloride with potassium vapor.
Erbium + Air
As discussed, erbium is relatively stable in dry air. However, when the air contains moisture, it will burn slowly to form erbium(III) oxide, Er2O3. Upon this reaction, erbium loses its shininess and will turn dull.
Erbium + Water
Erbium is electropositive, meaning its tendency is to lose electrons to form positive cations. When an electropositive element encounters another chemical that can easily accept electrons, an easy reaction occurs. When erbium reacts with water, it donates its outer electron to the hydrogen of the water molecule and forms erbium hydroxide, Er(OH)3. This reaction occurs slowly with cold water and quickly with hot water.
Erbium + Halogens
All of the halogens react well with erbium, forming erbium(III) halides. Fluorine, chlorine, bromine, and iodine will react with erbium to form erbium(III) fluoride, ErF3, erbium(III) chloride, ErCl3, erbium(III) bromide, ErBr3, and erbium(III) iodide, ErI3, respectively.
Erbium + Acids
When put in diluted sulfuric acid, erbium will readily dissociate to form a yellow solution containing Er(III) ions and hydrogen gas.
Erbium(III) oxides form when erbium burns in moisture-containing air. They appear as pink crystals that are insoluble in water and will dissociate in strong mineral acid solutions to form erbium(III) salts. Erbium oxides are very useful because they convert photons; Infrared light converts to ultraviolet light. Erbium oxide’s pink nanoparticles have increased electrical conductivity, toughness, and photoluminescence. Important applications of erbium oxides include the manufacturing of glass display, such as computer monitors, high temperature and corrosion-resistant coatings, and metal-oxide-semiconductor transistors. Furthermore, they increase opacity and are pink colorant for ceramics and porcelain.
Erbium halides include erbium(III) fluoride, erbium(III) chloride, erbium(III) bromide, and erbium(III) iodide. Erbium fluoride is an insoluble compound that is useful for oxygen-sensitive procedures. It is involved in metal production; To extract erbium, an electric current is passed through erbium fluoride. Additionally, erbium does not react well with hydrofluoric acid because erbium fluoride coats the surface of the metal. Erbium chloride is a pink, soluble solid that acts as a catalyst in reactions that form alcohols and phenols. This compound is moderately toxic and emits toxic fumes when heated, causing respiratory irritation. Erbium bromide is also soluble in water. Similarly to other bromide compounds, erbium bromide is used to treat water and to chemically analyze other minerals crystals. Erbium iodide is insoluble and appears as a light pink solid. It is involved in the synthesis of other chemicals and reacts well with oxidizing agents and strong acids.
Synthesis of Erbium
Erbium is a rare earth metal and is never found freely in nature. It occurs in monazite and bastnasite ores that are mainly mined in China and the United States. The primary method of extracting erbium is from xenotime and euxenite, as they are much better sources. To process erbium metal, erbium oxides are heated with calcium at 1450˚C. Another method of obtaining erbium is by converting erbium-containing mineral into erbium fluoride. Then, an electric current is passed through the compound to isolate pure erbium.
Erbium Oxidation States
Erbium exists almost exclusively in the +3 oxidation state, although there are some rare complexes with erbium in the +1 and+2 oxidation states. The Er3+ ion is pink in color when in solution. As stated, this pink color makes erbium an excellent coloring agent.
Properties of Erbium
- Melting point: 1802 K; 1529°C; 2784°F
- Boiling point: 3141 K; 2868°C; 5194°F
- Density: 9.07 g/cm3
- Atomic weight: 167.259
- Atomic number: 68
- Electronegativity: 1.24
- Classification: Lanthanide
- Natural abundance in the Earth’s crust: 0.0034%
- Electron shell configuration:[Xe] 4f12 6s2
- Isotopes: Six stable isotopes: 162Er, 164Er, 166Er,167Er, 168Er, 170Er
- Found naturally in the minerals: Found mainly in monazite and bastnaesite
- Toxicity: Erbium compounds are nontoxic, while pure erbium is slightly toxic
Where can I buy Erbium?
Samples of erbium metal can be purchased from Amazon and specialty shops. However, be careful- this metal is expensive, costing about $650 per kilogram.