Structural and electrical study of the alluaudites (Ag1−xNax)2FeMn2(PO4)3 (x=0, 0.5 and 1)

Ag3V2(PO4)2F3, a new compound obtained by Ag+/Na+ ion exchange into the Na3V2(PO4)2F3 framework

“…As reviewed by Shannon 41 , the effective ionic radii for 6-coordinated Na + and Please do not adjust margins Please do not adjust margins Ag + are 1.02 Å and 1.15 Å, respectively. This unit cell increase is in line with what is observed for the Na/Ag substitution in other materials families, such as alluaudites 13 and materials of composition Ag7-xNaxFe3(X2O7)4 (X = P, As) [16][17][18] . BVS calculation: V average oxidation state = +3.04 (4) In Na3V2(PO4)2F3, sodium ions are found in planes at z = 0 and z = ½, distributed on a "triangular" arrangement of three crystallographic sites Na(1), Na(2) and Na(3) (Figure 4) 31 .…”

“…The high ionic conductivity of silver-based compounds has been known since the investigation of AgI and related compounds 9 . Among other Ag-conducting investigated compositions one finds open structures of NASICON-type such as Ag1+xZr2-2xMx(PO4)3 (M = Sc, Fe 10 ), AgTaMP3O12 (M = Al, Ga, In, Cr, Fe and Y) 11 , AgSbMP3O12 (M = Al, Ga, Fe and Cr) 12 and other structural families such as (Ag1-xNax)2FeMn2(PO4)3 13 , Ag2VP2O8 14 , AgRu2(P2O7)2 15 and Ag7-xNaxFe3(X2O7)4 (X = P, As) [16][17][18] . The high ionic conductivity of these ceramics led to several applications into functional devices such as membranes, fuel cells and gas sensors 19,20 .…”

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

“…[ 6 -8 ] h a v e r e f i n e d t h e structures from powder x-ray diffraction data of various phases by Reitveld method. It is also worth to mention the structural refinements reported by Daidouch et al [9,10] using also powder diffraction patterns: XRD for the compounds Na 2 FeMn 2 (PO 4 ) 3 and NaAgFeMn 2 (PO 4 ) 3 and neutron for Ag 2 FeMn 2 (PO 4 ) 3 , by Daidouh et al These Authors have found a rather high reliability factors of order of 9, 11 respectively for the pure silver and sodium phase and even a higher value of 15.4 for NaAgFeMn 2 (PO 4 ) 3 .…”

“…The title compound and related solid solutions have been more recently investigated for Li-Na batteries applications and some structural refinements were made by the same Authors, using powder Rietveld method [11,12]. The reliability f a c t o r s a r e o f t h e s a m e o r d e r a s r e p o r t e d b y Daidouch et al [9,10]. To the best of our knowledge no single crystal structural resolution of the sodium iron manganese alluaudite phosphates has been yet performed.…”

Electrical Behavior of New Orthophosphates Na2M3(PO4)3 (M3=GaMn2, GaCd2, InMn2 and FeMnCd) with Alluaudite-Like Structure

“…ossbauer spectra of Ag 2 FeMn 2 (PO 4 ) 3 (5) and the ionic conductivity of (Ag 1Àx Na x ) 2 FeMn 2 (PO 4 ) 3 with x = 0, 0.5, and 1 (6). The alluaudite structure of both systems, deduced from room-temperature neutron diffraction measurements, allowed us to improve the distribution of the transition metals (Fe, Mn) along the edge-sharing MnO 6 -FeO 6 -MnO 6 octahedra, concluding that the cations Mn and Mn/Fe are located, respectively, in 4e and 8f positions.…”