Hexagonal, Lanthanoid, Pls

• Al-Eu-N-O-Si
• Al-Ba-Eu-Mg-O
• Ba-Cl-Eu-Gd-O-P
• Al-Ba-Eu-Mg-O-Si
• Ba-Cl-Eu-La-O-P
• lanthanoid
• rare earth
• luminescent
• nonmetal
• chalcogen