Chalcogen, Non-disordered, Quaternary, Energy gap for direct transition

• Ba-Cu-F-Se
• Ba-In-O-P
• Ag-Ge-Mn-Se
• Ag-F-O-S
• Cd-Cs-Se-Y
• quaternary
• chalcogen
• non-disordered
• transitional
• conductor
• orthorhombic
• monoclinic
• tetragonal
• trigonal
• hexagonal