Single Crystal X-Ray Structural Investigation of Alluaudite Related Monophosphate Na2FeMn2(PO4)3

• Main Authors: N. Dridi, El-H. Arbib, El H. Karni, F. Capitelli, B. Elouadi
• Format: Article
• Language: English
• Published: al-Farabi Kazakh National University 2010-11-01
• Series: Eurasian Chemico-Technological Journal
• Online Access: http://ect-journal.kz/index.php/ectj/article/view/502

The compound Na2FeMn2(PO4)3 has been successfully isolated with the alluaudite structural type. Accurate single crystal X-ray diffraction has allowed solving the structure with reliability factors of R1 and Rw equal to 0.0322 and 0.0790 respectively. It was found that the symmetry is monoclinic with a space group of C2/c and lattice parameters: a = 12.180(2) Å, b = 12.660(2) Å, c = 6.500(2) Å, B = 114.528(3)(°), unit cell volume = 911.8(3) Å3, Z = 8 and dcal.=3.618 g.cm-3. Three-dimensional network is formed by the [MnO6] octahedra linked in pairs to form Mn-based octahedral dimers: ([Mn2O10]). Each dimer shares six vertices with six tetrahedra [P(2)O4] to form sheets within the plane (100). The latter are connected by tetrahedra [P(1)O4] delimiting cages and tunnels which house either Fe3+ or Na+ cations. Each [FeO6] octahedron is linked to two [Mn2O10] dimers belonging to two adjacent sheets to form mixed Fe-Mn chains of the type: - Fe3+ - Mn2+ - Mn2+ - Fe3+ - Mn2+ - Mn2+ - Fe3+ - ..., running along the direction [101].