Investigation into the dehydration of selenate doped Na2M(SO4)2·2H2O (M = Mn, Fe, Co and Ni): Stabilisation of the high Na content alluaudite phases Na3M1.5(SO4)3-1.5x(SeO4)1.5x (M = Mn, Co and Ni) through selenate incorporation

Abstract

Investigation into the dehydration of selenate doped Na 2 M(SO 4) 2 •2H 2 O (M = Mn, Fe, Co and Ni): stabilisation of the high Na content alluaudite phases Na 3 M 1.5 (SO 4) 3-1.5x (SeO 4) 1.5x (M = Mn, Co and Ni) through selenate incorporation', Journal of Solid State Chemistry.

Synthesis and structures of sodium containing K2-xNaxMg2(SO4)3 langbeinite phases

“…These were prepared via a dissolution-evaporation route used previously for the synthesis of mixed metal sulphate systems [18][19][20]. In this method, stoichiometric amounts of Na2SO4, K2SO4 and MgSO4•7H2O were dissolved in water.…”

Topological Features of the Alluaudite-Type Framework and Its Derivatives: Synthesis and Crystal Structure of NaMnNi2(H2/3PO4)3

“…Because of the wide isomorphism in the cationic and anionic parts of the alluaudite-type structures, they attract interest as advanced materials for Li-ion batteries [22][23][24][25][26][27][28]. Despite the observed chemical diversity, Ni-containing alluaudite-type compounds are represented only by anhydrous phosphates Na 2 MNi 2 (PO 4 ) 3 (M = Fe, Al) [29,30] and CaFeNi 2 (PO 4 ) 3 [31], mixed phosphate-hydrogen phosphate AgNi 3 (PO 4 )(HPO 4 ) 2 [32], sulfate Na 2 Ni 2 (SO 4 ) 3 [33,34], and mixed sulfate-selenate Na 3 Ni 1.5 (SO 4 ) 3-1.5x (SeO 4 ) 1.5x [35].…”

Synthesis, Structure, and Conductivity of Alluaudite‐Related Phases in the Na2MoO4–Cs2MoO4–CoMoO4 System

“…The same effect with a probable substantially increased stability and composition range of sulfate‐based materials with extending the unit cell volumes, width and permeability of the bottlenecks for alkali‐ion transport channels can be reached with substitution of SO 4 2– by other large anions MoO 4 2– or WO 4 2– . As shown by us in,[3a] the homogeneity regions of nonstoichiometric double molybdates and tungstates of sodium and divalent metals with the alluaudite structures are Na 4–2 x M 2+ 1+ x ( T O 4 ) 3 ( M = Mg, Mn, Co, Ni, Zn; T = Mo, W; 0 ≤ x ≤ 0.5), which are much wider than those for Na 2+2 x M 2‐ x (SO 4 ) 3 ( M = Fe, Mn, Co; x ≈ 0.2–0.3)[2b], , and enriched with sodium. Taking into account promising electrochemical properties of Na 2.67 Mn 1.67 (MoO 4 ) 3 and the ionic conductivity of Na 3.6 M 1.2 (MoO 4 ) 3 ( M = Mg, Ni, Zn, Cd) and Na 3.6 Mg 1.2 (WO 4 ) 3 (5 10 –3 S cm –1 at 400 °C)[3a] of two orders higher than that of Na 2 R 3+ M 2+ 2 (PO 4 ) 3 [2a], [2c], we may expect developing in the future new effective mixed‐anion molybdate (tungstate) containing cathode materials of the alluaudite‐type for Li/Na‐ion batteries.…”

“…This approach allows one varying the chemical composition, stability and properties in wider ranges compared with ordinary “monoanionic” salts. Recently, mixed‐anion solid solutions Na x Fe y (PO 4 ) 3– z (SO 4 ) z (0 ≤ z ≤ 3) and Na 3 M 1.5 (SO 4 ) 3–1.5 x (SeO 4 ) 1.5 x ( M = Mn, Co, Ni) were obtained, which are considered to be prospective cathode materials for Li/Na‐ion batteries. It is noteworthy that, in the latter case, doping with larger selenate ions results in increase of the unit cell and maximum sodium content in the structure of the initial sulfate.…”