Solid solutions of bismuth-containing mixed-metal oxides: anisotropic structural changes with chemical substitutions

Michael Lufaso, Amanda Jessel, Victor Barbosa, Danielle Mason

University of North Florida

Bismuth-containing mixed-metal oxides are of interest for their dielectric, electrical, optical, and catalytic properties. The use of chemical substitutions enables some control of properties including the dielectric constant, conductivity, and the optical band gap. Substitution of specific ions result in incorporation into the host structure and typically induce simple isotropic structural changes that follow Vegard’s Law, whereas in certain systems anisotropic changes are exhibited in the structure. The extent of chemical substitutions and the impact on the crystal structures were examined in a series of experiments with varying phase compositions in selected mixed-metal oxide systems. Using powder X-ray diffraction and characterization using Rietveld refinements, non-linear structural changes were examined in compositions that crystallize with the Sillenite and Aurivillius structure types. Electrical and optical property measurements were conducted to investigate structure-property relationships.