Local structure of CuxZn2-xTiO4 inverse spinel.

Structural and vibrational changes due to the incorporation of Cu in the Cu_xZn_2-xTiO₄ inversespinel solid solution have been investigated by X-ray diffraction, Raman spectroscopy, and abinitio calculations. Both X-ray diffraction and Raman spectroscopy show that the structure remainscubic while the unit-cell volume decreases on Cu²⁺ incorporation. The compositional dependenciesof the Raman frequencies and linewidths indicate the incorporation of Cu²⁺ into tetrahedral sites. The A1g tetrahedral mode frequency becomes independent on composition for x > 0.6. This isattributed to the limited incorporation of Cu²⁺ in the tetrahedral sites at Cu-rich compositions. Abinitio calculations with quasi-random structures reveal only a slight energetic preference of Cu²⁺ for octahedral over tetrahedral sites. [ABSTRACT FROM AUTHOR]