Sintering, Structural and Optical Properties of Aurivillius Bi₄LaTi₃TMO₁₅ (TM = Co, Cr, Fe, Mn and Ni) Ceramics

Aurivillius Bi₄LaTi₃TMO₁₅ (TM = Co, Cr, Fe, Mn and Ni) ceramics were prepared by the conventional solid state reaction. Crystalline structures were determined by X-ray diffraction technique. Microstructures were characterized using field emission electron scanning microscopy, and typical plate-like grains but different grain morphologies are found in the Aurivillius compounds. Optical behaviors were measured by a UV-near-IR ellipsometer, and optical parameters are further extracted. Electronic structures with a direct inter-band transition are determined for all the Aurivillius ceramics. Finally, the values of the optical energy band gap (Eg^opt) of the Bi₄LaTi₃TMO₁₅ (TM = Co, Cr, Fe, Mn and Ni) samples are respectively calculated to be about 3.883, 3.948, 3.759, 3.891 and 3.967 eV through the Tauc's power law.