Transition metal
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a rare-earth element. Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.
The most important present-day use of yttrium is as a component of phosphors, especially those used in LEDs. Historically, it was once widely used in the red phosphors in television set cathode ray tube displays. Yttrium is also used in the production of electrodes, electrolytes, electronic filters, lasers, superconductors, various medical applications, and tracing various materials to enhance their properties.
Yttrium has no known biological role. Exposure to yttrium compounds can cause lung disease in humans.
In 1787, part-time chemist Carl Axel Arrhenius found a heavy black rock in an old quarry near the Swedish village of Ytterby (now part of the Stockholm Archipelago). Thinking it was an unknown mineral containing the newly discovered element tungsten, he named it ytterbite and sent samples to various chemists for analysis.
Johan Gadolin at the Royal Academy of Åbo (Turku) identified a new oxide (or "earth") in Arrhenius' sample in 1789, and published his completed analysis in 1794. Anders Gustaf Ekeberg confirmed the identification in 1797 and named the new oxide yttria. In the decades after Antoine Lavoisier developed the first modern definition of chemical elements, it was believed that earths could be reduced to their elements, meaning that the discovery of a new earth was equivalent to the discovery of the element within, which in this case would have been yttrium.
Friedrich Wöhler is credited with first isolating the metal in 1828 by reacting a volatile chloride that he believed to be yttrium chloride with potassium.
In 1843, Carl Gustaf Mosander found that samples of yttria contained three oxides: white yttrium oxide (yttria), yellow terbium oxide (confusingly, this was called 'erbia' at the time) and rose-colored erbium oxide (called 'terbia' at the time). A fourth oxide, ytterbium oxide, was isolated in 1878 by Jean Charles Galissard de Marignac. …
Yttrium is a soft, silver-metallic, lustrous and highly crystalline transition metal in group 3. As expected by periodic trends, it is less electronegative than its predecessor in the group, scandium, and less electronegative than the next member of period 5, zirconium. However, due to the lanthanide contraction, it is also less electronegative than its successor in the group, lutetium. Yttrium is the first d-block element in the fifth period.
The pure element is relatively stable in air in bulk form, due to passivation of a protective oxide (Y2O3) film that forms on the surface. This film can reach a thickness of 10 μm when yttrium is heated to 750 °C in water vapor. When finely divided, however, yttrium is very unstable in air; shavings or turnings of the metal can ignite in air at temperatures exceeding 400 °C. Yttrium nitride (YN) is formed when the metal is heated to 1000 °C in nitrogen.
The similarities of yttrium to the lanthanides are so strong that the element has been grouped with them as a rare-earth element, and is always found in nature together with them in rare-earth minerals. Chemically, yttrium resembles those elements more closely than its neighbor in the periodic table, scandium, and if physical properties were plotted against atomic number, it would have an apparent number of 64.5 to 67.5, placing it between the lanthanides gadolinium and erbium. …
Yttrium is found in most rare-earth minerals, and some uranium ores, but never in the Earth's crust as a free element. About 31 ppm of the Earth's crust is yttrium, making it the 43rd most abundant element. Yttrium is found in soil in concentrations between 10 and 150 ppm (dry weight average of 23 ppm) and in sea water at 9 ppt. Lunar rock samples collected during the American Apollo Project have a relatively high content of yttrium.
Yttrium is not considered a "bone-seeker" like strontium and lead. Normally, as little as 0.5 milligrams (0.0077 gr) is found in the entire human body; human breast milk contains 4 ppm. Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. With as much as 700 ppm, the seeds of woody plants have the highest known concentrations.
As of April 2018 there are reports of the discovery of very large reserves of rare-earth elements in the deep seabed several hundred kilometers from the tiny Japanese island of Minami-Torishima Island, also known as Marcus Island. This location is described as having "tremendous potential" for rare-earth elements and yttrium (REY), according to a study published in Scientific Reports. "This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features," the study reads. …
The red component of color television cathode ray tubes is typically emitted from an yttria (Y2O3) or yttrium oxide sulfide (Y2O2S) host lattice doped with europium (III) cation (Eu3+) phosphors. The red color itself is emitted from the europium while the yttrium collects energy from the electron gun and passes it to the phosphor. Yttrium compounds can serve as host lattices for doping with different lanthanide cations. Tb3+ can be used as a doping agent to produce green luminescence. As such yttrium compounds such as yttrium aluminium garnet (YAG) are useful for phosphors and are an important component of white LEDs.
Yttrium is used in the production of a large variety of synthetic garnets, and yttria is used to make yttrium iron garnets (Y3Fe5O12, "YIG"), which are very effective microwave filters Yttrium, iron, aluminium, and gadolinium garnets (e.g. Y3(Fe,Al)5O12 and Y3(Fe,Gd)5O12) have important magnetic properties. YIG is also very efficient as an acoustic energy transmitter and transducer. Yttrium aluminium garnet (Y3Al5O12 or YAG) has a hardness of 8.5 and is also used as a gemstone in jewelry (simulated diamond). Cerium-doped yttrium aluminium garnet (YAG:Ce) crystals are used as phosphors to make white LEDs.
YAG, yttria, yttrium lithium fluoride (LiYF4), and yttrium orthovanadate (YVO4) are used in combination with dopants such as neodymium, erbium, ytterbium in near-infrared lasers. YAG lasers can operate at high power and are used for drilling and cutting metal. …
Yttrium in the Solar System was created by stellar nucleosynthesis, mostly by the s-process (≈72%), but also the r-process (≈28%). The r-process consists of rapid neutron capture by lighter elements during supernova explosions. The s-process is a slow neutron capture of lighter elements inside pulsating red giant stars.
Yttrium isotopes are among the most common products of the nuclear fission of uranium in nuclear explosions and nuclear reactors. In the context of nuclear waste management, the most important isotopes of yttrium are 91Y and 90Y, with half-lives of 58.51 days and 64 hours, respectively. Though 90Y has a short half-life, it exists in secular equilibrium with its long-lived parent isotope, strontium-90 (90Sr) (half-life 29 years).
All group 3 elements have an odd atomic number, and therefore few stable isotopes. Scandium has one stable isotope, and yttrium itself has only one stable isotope, 89Y, which is also the only isotope that occurs naturally. However, the lanthanide rare earths contain elements of even atomic number and many stable isotopes. Yttrium-89 is thought to be more abundant than it otherwise would be, due in part to the s-process, which allows enough time for isotopes created by other processes to decay by electron emission (neutron → proton). …
Yttrium can be highly toxic to humans, animals and plants.
Water-soluble compounds of yttrium are considered mildly toxic, while its insoluble compounds are non-toxic. In experiments on animals, yttrium and its compounds caused lung and liver damage, though toxicity varies with different yttrium compounds. In rats, inhalation of yttrium citrate caused pulmonary edema and dyspnea, while inhalation of yttrium chloride caused liver edema, pleural effusions, and pulmonary hyperemia.
Exposure to yttrium compounds in humans may cause lung disease. Workers exposed to airborne yttrium europium vanadate dust experienced mild eye, skin, and upper respiratory tract irritation—though this may be caused by the vanadium content rather than the yttrium. Acute exposure to yttrium compounds can cause shortness of breath, coughing, chest pain, and cyanosis. The Occupational Safety and Health Administration (OSHA) limits exposure to yttrium in the workplace to 1 mg/m3 (5.8×10−10 oz/cu in) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) is 1 mg/m3 (5.8×10−10 oz/cu in) over an 8-hour workday. At levels of 500 mg/m3 (2.9×10−7 oz/cu in), yttrium is immediately dangerous to life and health. Yttrium dust is highly flammable.