Synthèse et structure cristalline de Na3NbO(AsO4)2

✍ Scribed by Khaled Hizaoui; Noureddine Jouini; Tahar Jouini

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 545 KB
• Volume: 144
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.8116

✦ Synopsis

The compound Na 3 NbO(AsO 4 ) 2 was prepared by a solid-state reaction. It crystallizes in the monoclinic system, space group P2 1 /n, with a ‫؍‬ 9.637(3) A s , b ‫؍‬ 8.509(2) A s , c ‫؍‬ 10.593(2) A s , ‫؍‬ 108.67(2)°, M ‫؍‬ 455.72, V ‫؍‬ 822.9(4) A s 3 , Z ‫؍‬ 4, ‫؍‬ 3.687 g cm ؊3 . The crystal structure was refined (137 variables) from 1440 independent reflections collected on a Nonius CAD4 automatic diffractometer with MoK radiation. The final R index and weighted wR index are 0.022 and 0.045, respectively. The three-dimensional network is built up from NbO 6 octahedra and AsO 4 tetrahedra-sharing corners; each NbO 6 octahedron is bonded to five AsO 4 tetrahedra. This arrangement delimits three different tunnels running along [100], [010], and [001], respectively, at the intersection of which the sodium ions are located in a six-coordination mode. This structure is compared with those of the A 3 MX 2 O 9 (A ‫؍‬ Na, K; M ‫؍‬ Nb, Sb; X ‫؍‬ P, As).