Low-temperature Raman spectra of YbVO4

This paper reports on the spectroscopic study of YbVO4 in the range 10-300 K. All the Raman phonons were properly assigned. Temperature-dependent Raman spectra showed no anomalous changes, which indicate that neither structural phase transition nor strong electron-phonon coupling occur, at least within this temperature range. This result is sharp contrast to those of YbPO4 where strong mixing of the upper crystal-field states Gamma(6) and Gamma(7) with an E-g(3) phonon at room-temperature occurs. A possible explanation for the absence of electron-phonon coupling in YbVO4 is the occurrence of the Gamma(6) state at energy higher than the E-g(3) phonon, unlike the coincidence of Gamma(6) and E-g(3) energies in YbPO4. (c) 2007 Elsevier B.V. All rights reserved.