Low-Dimensional Gadolinium Polyselenides: Thermodynamic Modelling, Crystals Growing and Crystal Structure

By thermodynamic modelling of the Gd—Se—I system, the optimal growth conditions for crystalline GdSe1.85 and GdSe1.80 gadolinium polyselenides, whose existence was proved in our previous works, have been determined. Based on the obtained information, the GdSe1.85 and GdSe1.80 crystals are grown by the vapor transport technique using iodine as the transport agent. The crystals produced are identified by microprobe and powder Xray diffraction analysis. It is shown that in case of GdSe1.85 the crystal structure is typical for rare-earth polychalcogenide structures, but the unit cell represents metrically a previously unknown type.