Ice Bath Assisted BiMn2O5(Mullite) Phase Synthesis, Structural and Compositional Analysis under Different Bi Concentration

Abstract

In this work, ice bath assisted co-precipitation synthesis of nanostructured Bismuth Manganite (BiMn2O5) with varied bismuth concentration and their consequences on the structural properties have rationally been investigated for first time in reports. The novelty of this study is to primarily elucidate the crystalline phase formations and related structural as well as compositional changes while fabricating BiMn2O5 with different amount of Bi content up to 20% to compensate the volatile Bi during annealing process. Powder X-ray diffraction and Rietveld Refinement techniques evidently confirmed the formation of single-phase mullite-type orthorhombic perovskite structure for stoichiometric ratio; while increasing Bi content, a secondary phase sillenite (Bi24Mn2O40) was formed which also gradually increased with increase in bismuth in the precursor solution. Rod and cubic shaped morphologies were commonly observed and size of the particles shows particle size ranging between 45 nm and 120 nm with increase of bismuth content. The mixed morphology is inevitably due to the presence of the secondary phases due to increasing Bi content that are evident from the XRD results. Raman and Optical properties evidently confirmed the structural variation and changes in the band gap respectively owing to the increase in secondary phase evolution with excess bismuth content. X-ray photoelectron spectroscopy (XPS) studies confirmed the increment in Bi content and the coexistence of Mullite and Sillenite phases in the samples.