Alkali, Chalcogen, Energy gap for direct transition

• Cs-Tb-Te-Zn
• K-Se
• Cd-Cs-Se-Y
• Cs-Hg-Se-Y
• Na-S
• chalcogen
• alkali
• non-disordered
• transitional
• conductor
• orthorhombic
• trigonal
• monoclinic
• tetragonal
• cubic