Raman spectra of Ba2CuxZn1-xWO6mixed crystals (x=0.0 to 0.4 andx=1) are reported and shown to display considerable enhancement of Raman intensity for the WO6vibration withEg(Oh) symmetry when increasing the concentration of Cu2+. Ab initio calculations of Raman frequencies and intensities for a W(OH)6model cluster indicate that theA1g(D4H) component of this vibration may gain considerable intensity via mixing with the totally symmetric stretchingA1g(Oh) vibration when lowering the symmetry fromOhtoD4h, thus reflecting an indirect influence of Jahn-Teller distorted CuO6centers on neighboring WO6octahedra. Similarly striking is the change of the Raman spectrum in the energy region of theT2gmodes, when switching from the cubic phase with disordered local distortions in the CuO6-WO6frame to the long-range cooperative Jahn-Teller order in Ba2CuWO6. It is concluded that Raman spectra can be used as a rather sensitive probe for detecting Jahn-Teller distortions in mixed crystals, thus providing a valuable addition to other spectroscopic techniques.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry