Structural and optical study of γ –BIMEVOX; ME: Ba2+ and Sr2+

Abstract

Bismuth oxide based compounds, such as Bi 4 V 2 O 11-δ (BIVOX) , exhibit Aurivillus type of interleaving arrangement of (Bi 2 O 2 ) 2+ and (VO 3 □ 0.5 ) 2-(□: oxygen vacancies). Bi 4 V 2 O 11-δ, is known to have three kinds of temperature dependent interconvertible polymorphs α (monoclinic), β (orthorhombic) and γ (tetragonal). Out of all the three phases, the γ -phase is highly disordered and hence, is the most conductive one which can be stabilized by proper lower valence cation (ME) doping at V site. Bi 4 V 1.90 ME 0.20 O 11-δ (ME: Ba 2+ and Sr 2+ ) were prepared via splat quenching technique. The required compositions were melted at 1250 C in an electric furnace. The as quenched samples were sintered at 800 C for 12 hours (h). The formed phases were analyzed using X-ray diffraction on quenched and sintered samples, the peak at 32 is found to be singlet in all the samples which confirms the presence of γ-phase. Hence, the stabilization of γ-phase with tetragonal structure was found to have taken place with doping and quenching. These samples are also studied by FT-IR and UV/vis spectroscopy to investigate the effect of dopants on structure and band gaps respectively.