Resolving the structure of V₃O₇·H₂O and Mo-substituted V₃O₇·H₂O

Abstract

Vanadate compounds, such as V3O7·H2O, are of high interest due to their versatile applications as electrode material for metal-ion batteries. In particular, V3O7·H2O can insert different ions such as Li+, Na+, K+, Mg2+ and Zn2+. In that case, well resolved crystal structure data, such as crystal unit-cell parameters and atom positions, are needed in order to determine the structural information of the inserted ions in the V3O7·H2O structure. In this work, fundamental crystallographic parameters, i.e. atomic displacement parameters, are determined for the atoms in the V3O7·H2O structure. Furthermore, vanadium ions were substituted by molybdenum in the V3O7·H2O structure [(V2.85Mo0.15)O7·H2O] and the crystallographic positions of the molybdenum ions and their oxidation state are elucidated.

Prussian blue analogues with Na2NixCoyMnzFe(CN)6-multimetallic structures as positive and hydrogen vanadate as negative electrodes in aqueous Na-ion batteries for solar energy storage applications

“…The negative active material, namely, HVO, was also structurally characterized by PXRD analysis through Rietveld refinement. 35 Fig. 3(a) depicts the Rietveld refinement of HVO with unit cell parameters and obtained reliability factors, and Fig.…”

“…3(b) shows the resulting crystal structure. 35 The layers of edge-shared VO 6 octahedra in the b – c plane are stacked along the crystallographic a -direction. The layers are interconnected by means of hydrogen bonding.…”

“…The negative active material, namely, HVO, was also structurally characterized by PXRD analysis through Rietveld refinement. 35 crystalline H 2 O molecules. 36 The SEM image and EDX profile of HVO are presented in Fig.…”

Exploring the Insertion Mechanisms of Metal Cations into V3O7·H2O

“…Full pattern refinement (Le Bail fit, full pattern refinement without atomic information) was performed with TOPAS. 48 Starting values for cell parameters were taken from Schoiber et al 49 Concerning the goodness of fit, R wp values between 5 and 8% were typically reached for the Le Bail fits. The errors of the refined lattice parameters, as determined by the software TOPAS, were in the range of 0.007 Å for a in all measurements, which equals 0.04% relative to the reference value for a, as stated in Table S1.…”

“…Full pattern refinement (Le Bail fit, full pattern refinement without atomic information) was performed with TOPAS . Starting values for cell parameters were taken from Schoiber et al . Concerning the goodness of fit, R wp values between 5 and 8% were typically reached for the Le Bail fits.…”