Sr2CoWO6 perovskite has been prepared in polycrystalline form by solid-state reaction at 1150 °C. This material has been studied by high-resolution synchrotron X-ray and neutron powder diffraction (NPD), magnetic measurements, and differential scanning calorimetry (DSC). At room temperature, the crystal structure is tetragonal, space group I4/m, with a = 5.58277(1) Å and c = 7.97740(1) Å. The structure contains alternating CoO6 and WO6 octahedra, tilted in anti-phase by 7.24° in the basal ab plane along the [001] direction of the pseudocubic cell. This corresponds to the a 0 a 0 c - Glazer's notation as derived by Woodward for 1:1 ordering of double perovskites, consistent with space group I4/m. DSC and NPD measurements as a function of temperature indicate a structural transition from tetragonal to monoclinic (space group P21/n) at 260 K. At 2 K the cell parameters are a = 5.61267(8) Å, b = 5.58753(8) Å, c = 7.8994(1) Å, and β = 90.041(3)°. The structure contains alternating CoO6 and WO6 octahedra, tilted in-phase by 4.77° along the [001] direction of the pseudocubic cell and in anti-phase by 5.82° along the [010] and [100] directions. This corresponds to the a - a - c + Glazer's notation as derived by Woodward for 1:1 ordering in double perovskites, consistent with space group P21/n. Magnetic and neutron diffraction measurements indicate an antiferromagnetic ordering below T N = 24 K. The magnetic moment calculated through the linear fit of the Curie−Weiss law at high temperatures (5.20 μB) indicates that the orbital contribution is unquenched at high temperatures, which is consistent with high-spin Co2+ (4T1g ground state) in a quasi-regular octahedral environment. As prepared, the sample is an electrical insulator. Magnetic and electrical properties and bond valence sums are consistent with the electronic configuration Co2+(3d7)−W6+(5d0).

Ternary chalcogenides (AB 2 X 4 ) based on the spinel structure are gaining a great deal of attention because of the possibility of tuning their magnetic and optoelectronic properties not only by changing chemical composition but also by altering their degree of inversion. Here we report a rapid highpressure synthetic method for the synthesis of MIn 2 S 4 powders starting from commercially available solid sulfides. We prove the versatility of our method by reporting the synthesis of six members of the MIn 2 S 4 family (M = Mn, Fe, Co, Ni, Zn, and [a] 1558 Cd) under high-pressure conditions (3.5 GPa); these compounds show complete to moderate degrees of inversion. Furthermore, this family covers a spectral region that includes visible band gaps. Interestingly, the structural refinement carried out by Xray and neutron diffraction allows one to establish positive correlations between the gap and different parameters, including the degree of inversion. Finally, as a proof-of-concept, these ternary chalcogenides show moderate photocatalytic hydrogen production from aqueous solutions. and semiconducting properties, [2,3] whereas others show photoluminescence [4] and have found applications as photoconverters. [5] Eur. J. Inorg. Chem. 2016, 1558-1565 www.eurjic.org