- Yttrium (Y) is a transition metal with atomic number 39, located in Group 3 of the periodic table, directly above the lanthanides.
- It is a silvery-white, lustrous metal that is relatively stable in air due to the formation of a thin oxide layer, but it can react slowly with water and more vigorously at elevated temperatures.
- Yttrium has three valence electrons—two in the 5s subshell and one in the 4d subshell—and it typically exhibits the +3 oxidation state in its compounds. Its atomic structure consists of thirty-nine protons, typically fifty neutrons, and thirty-nine electrons arranged in five shells.
- Naturally occurring yttrium is composed entirely of a single stable isotope, yttrium-89 (⁸⁹Y), though numerous radioactive isotopes are known, with yttrium-90 (⁹⁰Y) being important in medicine.
- Yttrium is relatively abundant in the Earth’s crust at about 33 parts per million, comparable to cobalt, but it is never found in pure metallic form. It occurs in association with rare-earth elements in minerals such as xenotime (YPO₄), monazite ((Ce,La,Nd,Th)PO₄), and bastnäsite ((Ce,La)(CO₃)F), as well as in gadolinite. Significant deposits are found in China, Malaysia, India, Brazil, the United States, and Australia. Yttrium is usually obtained as a by-product during the processing of rare-earth minerals.
- The element was discovered in 1794 by Finnish chemist Johan Gadolin, who identified a new oxide (yttria) in a mineral from the quarry in Ytterby, Sweden. Metallic yttrium was first isolated in 1828 by Friedrich Wöhler through the reduction of yttrium chloride (YCl₃) with potassium. The name derives from Ytterby, which has also given its name to several other elements (terbium, erbium, ytterbium).
- Yttrium has a wide range of applications, particularly in electronics, materials science, and medicine. Yttrium oxide (Y₂O₃) is used in the production of phosphors for color television and LED displays, especially in the red component of RGB systems. Yttrium is also used in superconductors, notably yttrium barium copper oxide (YBa₂Cu₃O₇, YBCO), which operates at relatively high temperatures for a superconductor. In the ceramics industry, yttria-stabilized zirconia (YSZ) is used for thermal barrier coatings in jet engines and gas turbines due to its high-temperature stability and low thermal conductivity.
- In medicine, the radioactive isotope yttrium-90 (⁹⁰Y) is used in targeted cancer therapies, including radioembolization for liver cancer and radiopharmaceuticals for treating lymphoma. Yttrium aluminum garnet (Y₃Al₅O₁₂, YAG) is an important synthetic crystal used in lasers, both undoped and doped with neodymium (Nd:YAG lasers), for applications ranging from industrial cutting and welding to medical surgery and cosmetic treatments.
- Chemically, yttrium behaves like the heavier rare-earth elements (lanthanides), forming colorless salts such as yttrium chloride (YCl₃) and yttrium nitrate (Y(NO₃)₃). It reacts with oxygen to form Y₂O₃, with halogens to form halides, and with water or acids to produce hydrogen gas.
- Biologically, yttrium has no known essential role in living organisms and is considered to have low toxicity in stable form. However, soluble compounds can be mildly toxic if inhaled or ingested in large quantities.
- From an environmental perspective, yttrium is not considered a significant pollutant, but mining and refining of rare-earth minerals containing yttrium can produce environmental challenges, including radioactive waste if thorium or uranium are present in the ore.
