Local structure analysis of Bi2(Ga1-xFex)4O9 mullite-type solid solutions synthesized via combination of ball milling and thermal treatment

Abstract Mullite-type Bi 2 (Ga 1- x Fe x ) 4 O 9 solid solutions, with 0.1 ≤  x  ≤ 0.9, have been synthesized by a combination of mechanical and thermal treatments of a Bi 2 O 3 /Ga 2 O 3 /α-Fe 2 O 3 stoichiometric mixture. The microstructure of the as-prepared materials on the long-range and local atomic scales was investigated by X-ray diffraction and 57 Fe Mossbauer spectroscopy, respectively. The XRD data analysis revealed in all cases linear dependence of the lattice parameters related on x . Due to the ability of the applied Mossbauer spectroscopy to probe the local environment of Fe cations, the local structural disorder in investigated solid solutions is provided. It was shown that the presence of Fe 3+ cations in octahedral sites of the orthorhombic structure causes a local distortion of polyhedra in the material. The preferential occupation of Fe in octahedral site was revealed. Detailed quantitative information on both the cation distribution and the bond lengths provided is discussed in relation to the derived hyperfine parameters.