Structural and spectroscopic studies of BiTa1-xNbxO4

Polycrystalline samples of type BiTa1-xNbxO4 (0≤x≤1) in both the orthorhombic and triclinic phases have been characterized by a combination of powder X-ray diffraction, UV-Vis and Raman spectroscopy. The addition of Nb to BiTaO4 subtly alters the structure and spectroscopic properties of both the orthorhombic and triclinic oxides. The difference in bonding from the Nb 4d and Ta 5d electrons results in an unusual variation in the cell parameters in the orthorhombic form. In both structural types the addition of Nb results in a shift of the strong UV-Vis absorption feature towards the visible region. This feature noticeably broadens and shifts towards lower energy in the triclinic structures