Crystal Structure and Polarized Raman Spectra of Ca6Sm2Na2(PO4)6F2

✍ Scribed by Mohamed Toumi; Leila Smiri-Dogguy; Alain Bulou

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 156 KB
• Volume: 149
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8531

✦ Synopsis

The crystal structure of a new apatite Ca 6 Sm 2 Na 2 (PO 4 ) 6 F 2 has been determined using 842 independent re6ections (R ‫؍‬ 0.059, R w ‫؍‬ 0.076). The unit cell constants are a ‫؍‬ 9.3895(3) A > , c ‫؍‬ 6.8950(4) A > with P6 3 /m space group. The structure contains disordered cations in both the Ca(1) and the Ca(2) sites. The formula assigned to the compound is Ca 1.57 Sm 0.43 Na 2 Ca 4.43 Sm 1.57 (PO 4 ) 6 F 2 . The Raman spectra have been studied and they are consistent with the proposed structure. A comparison with 6uorapatite shows that most of the Raman lines of the new compound are signi5cantly broad, which is attributed to the random distribution of three kinds of atoms on the cation sites.