Vibrational raman and optical studies of Cm in zirconia-based pyrochlores and related oxide matriees.

Raman spectroscopy has been employed tofollow the phase behavior of Cm-Zr oxide materials as a function of Cm:Zr ratio. Three differentstructural phases, monoclinic, cubic and pyrochlore, are formed when the Cm:Zr ratio is varied from >0 to 1. Each phase produces a distinct Raman profile in the 100-700 cm−1 spectral region. Up to 10 atom % Cm, the Raman spectra indicate that the monoclinic structure is dominant. Raman bands corresponding to the monoclinic phase are absent in samples containing 20-40 atom % Cm. Concomitantly, a band at ~600 cm−1 broadens and increases in intensity with increasing curium content, indicating that the cubic phase is dominant in this concentration range. The pyrochlore oxide structure, which forms at 50 atom % Cm, generates three Raman bands (the center of mass are at 283,387, 495 cm−1) out of six bands predicted by nuclear site group analyses. The strongest of these is at 283 cm−1, and corresponds to the O-Cm-O bending mode.Details of these studies will be compared and discussed with data obtained for comparable systems containing selected analogous 4f-elements. © 2014 Taylor and Francis Group, LLC.