Sodium iron sulfate alluaudite solid solution for Na-ion batteries: moving towards stoichiometric Na2Fe2(SO4)3

The elusive Na2Fe2(SO4)3 stoichiometric compound was obtained through a precipitation method and is electrochemically active as a cathode.

Thermodynamic assessment of Hafnium Iridium binary system

The Hf–Ir system has been thermodynamically modeled by the CALPHAD approach. Hf2Ir, αHfIr, βHfIr, γHfIr (high temperature phase) and HfIr3 which have a homogeneity range, were treated as the formula (Hf,Ir)x:(Ir,Hf)1−x by a two-sublattice model with a mutual substitution of Hf and Ir in both sublattices.Hf5Ir3 has been treated as a stoichiometric compound while a solution model has been used for the description of the FCC (Ir) solid solution. Additionally, two different models describing the excess Gibbs energy for the liquid and for the solid solutions (BCC, FCC and HCP) were used and their predictions are compared. The calculations based on the thermodynamic modeling are in good agreement with the phase diagram data and experimental thermodynamic values available in the literature.

Experimental Investigation of the Phase Equilibria in the Al-Mn-Zn System at 400°C

Al-Mn-Zn ternary system is experimentally investigated at 400°C using diffusion couples and key alloys. Phase relationships and homogeneity ranges are determined for binary and ternary compounds using EPMA, SEM/EDS, and XRD. Reported ternary compound T3 (Al11Mn3Zn2) is confirmed in this study and is denoted as τ2 in this paper. Two new ternary compounds (τ1 and τ3) are observed in this system at 400°C. τ1 is determined as a stoichiometric compound with the composition of Al31Mn8Zn11. τ3 has been found to have homogeneity range of AlxMnyZnz (x=9–13 at%; y=11–15 at%; z=75–77 at%). The binary compounds Al4Mn and Al11Mn4 exhibit limited solid solubility of around 6 at% and 4 at% Zn, respectively. Terminal solid solution Al8Mn5 is found to have maximum ternary solubility of about 10 at% Zn. In addition, ternary solubility of Al-rich β-Mn′ at 400°C is determined as 4 at% Zn. Zn-rich β-Mn′′ has a ternary solubility of 3 at% Al. The solubility of Al in Mn5Zn21 is measured as 5 at%. Based on the current experimental results, the isothermal section of Al-Mn-Zn ternary system at 400°C has been constructed.

Investigation on solid solubility and magnetism of the non-stoichiometric compound Fe3Se4

In order to complete the research on the Fe–Se binary system, the phase structures with selenium contents from 50 to 60 at.% have been studied. Fe–Se binary samples used in this study were prepared by the high-temperature solid-state reaction method, and the phase structure of each sample was determined by powder X-ray diffraction. The solid solubility of the Fe3Se4 phase was determined to be from 56.1 to 57.6 at.% Se based on the values of unit-cell parameters. Magnetic properties of the samples were also studied.

Crystal architecture of R 2SnS5 (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides

The crystal structure of the R 2SnS5 (R = Pr, Nd, Gd and Tb) compounds has been investigated using X-ray single-crystal diffraction. Crystal architecture and structural relationships among U3S5, Y2HfS5, R 2SnS5 compounds are discussed and a structural origin is determined. It is shown that the complex architecture of the crystal structure of Eu5Sn3S12 is a result of interweaving of the simple crystal structures. The location of the copper ions in the non-stoichiometric compound Y2Cu0.20Sn0.95S5 is proposed on the basis of comparative analysis of the R—S interatomic distances in the R 2SnS5 series of compounds.