Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. metal
8. [metal by composition or origin]
9. nonferrous metal

Additional parents:

1. top of the aat hierarchies
2. Materials Facet
3. Materials
4. materials
5. materials by form
6. materials by chemical form
7. elements
8. rare earth elements

Anotations

Scope note:

Chemical element having symbol Y and atomic number 39. Yttrium resembles lanthanide metals very closely and is often classified as a ‘rare earth element.' Yttrium’s most important use is for making the phosphors used in television screen displays and in LEDs. Yttrium phosphors emit a clear red light when excited by electrons.