Correlating structures and magnetic order in layered iron oxide chalcogenides.

We will use high resolution X-ray powder diffraction to structural subtleties in mixed-valent iron oxide chalcogenides and to correlate the structures with electronic and magnetic properties. We will use ID22 in a standard setup with 38 keV X-rays with powders of Sr3Fe4S2O6, Sr2CaFe4S2O6, Sr1.5Ca1.5Fe4S2O6 and Sr4Fe4S2O7. We will examine the structural subtleties (small distortions and incommensurability) and sample variation in Sr3Fe4S2O6 and the temperature evolution of all samples through low temperature magnetic ordering transitions. ID22 at the ESRF offers the optimal combination of high resolution and high signal-to-noise ratio to answer these questions.