Chalcogen, Lanthanoid, Nonmetal, Energy level diagram, Tetragonal

• Er-O-V-Y-Yb
• Er-Gd-O-V-Yb
• Ca-Eu-O-W
• Ca-Mo-O-Tb
• Er-Eu-Mg-O-Si-Sr
• rare earth
• nonmetal
• lanthanoid
• chalcogen
• luminescent