Crystal Structure and Magnetic Properties of a New Iron(III) Silicophosphate Fe3P5SiO19 Studied by Neutron Diffraction and Mössbauer Techniques

The first Fe-based Na+-ion cathode with two distinct types of polyanions: Fe3P5SiO19

“…1b) showed that a phase-pure sample could be obtained using a conventional solid state method. The space group and cell parameters were determined to be hexagonal with the space group of P63 and a = 14.480(8) Å and c = 7.4256(2) Å, which were in excellent agreement with those reported by Elbouaanani et al 9 The detailed structural solution is shown in Table 1. Furthermore, the bond valence sum calculation is consistent with the oxidation state of all the cations in the compound (Table 2), verifying the structural model in the Rietveld analysis.…”

“…1a) is composed of Fe 2 O 9 dimers of two face-shared FeO 6 octahedra, Si 2 O 7 disilicates, and PO 4 tetrahedra. The structure was first studied by Elbouaanani et al via neutron diffraction in 2002, 9 which was found to be isostructural to two related members: Mo 3 P 5 SiO 19 and V 3 P 5 SiO 19 . 10,11 Although the difference in the ionic radii (r Fe 3+ = 0.785 Å, r V 3+ = 0.78 Å, r Mo 3+ = 0.83 Å) is up to 6%, M 3 P 5 SiO 19 (M = Fe, V and Mo) fit in the same space group, 12 suggesting good structural flexibility.…”

Li(MoO2)2O(AsO4)

“…type de groupement M 2 O 9 (M = Mo, Fe ou V) montre quelques points communs avec les structures des compose  s a Á charpente tridimensionnelle de formulation M 3 P 5 SiO 19 (M = Fe, Mo ou V) (Elbouaanani, Malaman, Ge  rardin & Ouladdiaf, 2002;Wang et al, 1988;Leclaire et al, 1986), Mo 4 P 6 Si 2 O 25 (Leclaire et al, 1988) et M 4 (P 2 O 7 ) 3 (M = Fe ou V) (Elbouaanani, Malaman, Ge  rardin & Ijjaali, 2002;Palkina et al, 1985). En effet, on rencontre dans les structures des deux familles M 3 P 5 SiO 19 et M 4 (P 2 O 7 ) 3 un type de ruban analogue, construit a Á partir d'un te  trae Á dre qui partage trois sommets avec respectivement trois dime Á res M 2 O 9 .…”