Energy level diagram, Lanthanoid, Rare earth

• Er-O-Y-Yb
• Er-La-O-V-Yb
• Al-Ce-O-Y
• Er-O-Y
• Er-O-V-Y-Yb
• lanthanoid
• rare earth
• luminescent
• chalcogen
• transitional
• cubic
• tetragonal
• orthorhombic
• monoclinic
• trigonal