Alkaline, Chalcogen, Disordered, Energy gap for direct transition

• Mg-O
• O-Sr-Ti
• Mg-O-Zn
• Ba-Cu-F-O-Y
• Ba-Bi-O-V
• chalcogen
• disordered
• alkaline
• conductor
• oxide
• cubic
• orthorhombic
• tetragonal
• hexagonal
• trigonal