Disordered, Transitional, Optics, Trigonal

• Bi-Fe-O
• Fe-O
• Li-Nb-O
• Ni-O
• Li-O-Ta
• phonons
• optical spectra
• Raman spectra
• wavenumber of optical phonon
• optical absorption
• transitional
• disordered
• chalcogen
• oxide
• non-disordered