Structures of two newly synthesized A_0.50SbFe(PO₄)₃ (A=Mn, Cd) Nasicon phases

Abstract

Crystal structures of A0.50SbFe(PO4)3(A=Mn, Cd) phases, obtained by solid state reaction at 920 °C, were determined at room temperature from X-ray powder diffraction (XRD) using the Rietveld method. The structures of the two samples are of the Nasicon-type with the R3 space group. Hexagonal cell parameters for A=Mn and Cd are: a=8.375(1) Å, c=21.597(2) Å and a=8.313(1) Å, c=21.996(2) Å, respectively. From XRD data, it is difficult to unambiguously distinguish between Cd2+ and Sb5+ ions in Cd0.50SbFe(PO4)3 and between Mn2+ and Fe3+ cations in Mn0.50SbFe(PO4)3. Nevertheless the overall set of cation–anion distances within the Nasicon framework clearly shows that the cation distribution can be illustrated by the {[A0.50]3a[◻0.50]3b}M1SbFe(PO4)3 (A=Mn, Cd) crystallographic formula. The divalent A2+ cations and vacancies are ordered within the two positions, 3a and 3b, of the M1 sites. Structure refinements show also a quasi-ordered distribution of Sb5+ and Fe3+ ions within the Nasicon framework. Thus, each A(3a)O6(A=Mn, Cd) octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (◻(3b)O6) site is located between two Sb5+O6 octahedra.

Structure, Infrared and Raman spectroscopic studies of the new Ba(NbV 0.5MIII0.5)(PO4)2 (MIII = Al, Cr, Fe, In) yavapaiite compounds ‘series

“…The other Raman bands observed at 350 cm -1 and 400 cm -1 could be assigned to the ν5(ONbO) and νM-O (M=Al, Fe, In) bands. Similar Raman bands, already observed at 364 and 370 cm -1 , were also attributed to Fe 3+ -O stretching modes in M0.5SbFe(PO4)3 (M = Mg, Ca, Ni, Sr, Pb) 12,15,16 and Li3Fe2(PO4)3 phases 34 . For [BaNbM] materials, the position of the ν6(ONbO) band should be predicted to be shown between 260 and 280 cm -1 within the region of the external mode.…”

“…As a result of various cationic substitution in A sites of A III PO4 phases, a new family of oxides crystallising in several basic types as Monazite, Zircon (Xenotime), Scheelite, Cheralite, Nasicon and Yavapaiite compounds type have been synthesized and characterized [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . Such materials can include a mixing of A II /M IV ions leading to the A II 0.5M IV 0.5PO4 formula which was often reported as A II M IV (PO4)2 form (A = Ca, Sr, Ba, Pb; M = Ti, Ge, Zr, Mo, Sn, Th, U, Np, Pu) [3][4][5][6][7][8] .…”

Structure, Infrared and Raman spectroscopic studies of new AII(SbV0.50CrIII0.50)(PO4)2 (A = Ba, Sr, Pb) yavapaiite phases

“…The larger A II cation can cause structural distortions, and more particularly, rotation of the PO4 tetrahedra. This last phenomenon leads to the synthesis of new families of phases whose structures are linked to each other's [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] . Among these families, the attracted A II M IV (PO4)2 yavapaiite-type phases have a structure consisting of layers of A II ions in tenfold coordination alternating with dense slabs of M IV O6 and PO4 polyhedra.…”

Crystalline Iron Oxohalide Nanotube Pea Pods

“…Further, the nonbonding side of the lone-pair elements naturally faces other nonbonding entities such as halide ions to generate extended nonbonding regions in solid-state structures. [1] In this paper, we report the synthesis of the first Sb 3+ -containing iron phosphates, Fe 7 (1) and Fe 7 Sb 3 (PO 4 ) 3 O 6 Br 3 (2), which are isostructural. A schematic overview of the structure is displayed in Figure 1.…”

“…A schematic overview of the structure is displayed in Figure 1. Four phosphate compounds containing Fe and Sb have been synthesized previously, all of them belonging to the NaSiCON structure family: A 0.50 SbFe(PO 4 ) 3 (A = Mn, Cd), [2] Sb 1.5 Fe 0.5 (PO 4 ) 3 , and Sb 0.5 Fe 0.5 P 2 O 7 . [3] However, all those compounds contain Sb 5+ ions and consequently feature 3-dimensionally continuous oxide networks rather than the reduced-dimensionality structure generated by the stereochemically active Sb 3+ lone-pairs in the present compounds.…”