Energy level diagram, Lanthanoid, Transitional

• Er-O-Ti
• Al-Ce-O-Y
• Br-La-U
• Al-Ce-O-Y-Yb
• Al-La-O-Sr-Ta-Yb
• rare earth
• transitional
• lanthanoid
• chalcogen
• nonmetal
• tetragonal
• cubic
• monoclinic
• trigonal
• orthorhombic