Yttrium

**Definition:** An element of the rare earth family of metals. It has the atomic symbol Y, atomic number 39, and atomic weight 88.91. In conjunction with other rare earths, yttrium is used as a phosphor in television receivers and is a component of the yttrium-aluminum garnet (YAG) lasers.

**Tree numbers:** - D01.268.558.975 - D01.268.956.890 - D01.552.550.975