Structure and bonding in cerium oxysulfide compounds. II—Comparative lattice dynamics calculations on Ce2O2S and Ce2.0O2.5S

✍ Scribed by C. Sourisseau; M. Fouassier; R. Mauricot; F. Boucher; M. Evain

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 288 KB
• Volume: 28
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199712)28:12<973::aid-jrs192>3.0.co;2-f

✦ Synopsis

Using the previously reported vibrational results (infrared, Raman and resonance Raman spectra) for the Ce 2 O 2 S and solid compounds (see Part I), comparative lattice dynamics calculations were performed. These Ce 2.0 O 2.5 S calculations allow one to reproduce satisfactorily the experimental wavenumbers and to propose more conÐdent vibrational assignments for the statistically disordered on the assumption of a symmetry crystal Ce 2.0 O 2.5 S, D 3 structure. In particular, it is shown that the cerium to oxygen bonding forces are distinct in the two oxysulÐdes : the f (Ce-O1) stretching force constants increase signiÐcantly from 90 N m-1 in the Ce3'-containing phase to Ce 2 O 2 S 110 and 140 N m-1 for the (Ce-O1) axial and equatorial forces, respectively, in the oxidation product. Ce 2.0 O 2.5 S The fact that the latter value (140 N m-1) compares well with that estimated in cerium dioxide supports CeO 2 previous conclusions from the optical study, i.e. that is more likely described as a Ce4'-containing Ce 2.0 O 2.5 S sample.