Yttrium aluminium garnet (YAG, Y3Al5O12) is a synthetic crystalline material of the garnet group. It is a cubic yttrium aluminium oxide phase, with other examples being YAlO3 (YAP) in a hexagonal or an orthorhombic, perovskite-like form, and the monoclinic Y4Al2O9 (YAM).
Yttrium aluminium garnet
Nd:YAG laser rod 0.5 cm in diameter.
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.
Yttrium
Left: Soluble yttrium salts reacts with carbonate, forming white precipitate yttrium carbonate. Right: Yttrium carbonate is soluble in excess alkali metal carbonate solution.
Mira is an example of the type of red giant star in which most of the yttrium in the solar system was created.
Johan Gadolin discovered yttrium oxide.