Structure Refinement of Five Layers Aurivillius Compound: Ba4Bi2Nb2Ti3O18

Abstract

The room temperature structures of the five layers Aurivillius phase Ba₄Bi₂Nb₂Ti₃O₁₈ has been refined from X-ray powder diffraction data using the Rietveld method. The structures consist of [Bi₂O₂]²⁺ layers interleaved with perovskite-like [Ba₄Nb₂Ti₃O₁₆]^2- blocks. The oxides was found to be orthorhombic (SG B2cb); a = 5.5017(8), b = 5.5031(8), c = 50.363(3) , R_p = 25.53 R_wp = 35.54 R_exp = 29.30 R_Bragg = 9.92. The structural features of the compound is found similar to that of other layered Aurivillius compounds. Using the available structural data the ferroelectric properties could be explained and strategies to find good ferroelectric materials could be inferred.