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

摘要

By thermodynamic modelling of the Gd-Se-I system, the optimal growth conditions for crystalline GdSe_(1.85) and GdSe_(1.80) gadolinium polyselenides, whose existence was proved in our previous works, have been determined. Based on the obtained information, the GdSe_(1.85) and GdSe_(1.80) crystals are grown by the vapor transport technique using iodine as the transport agent. The crystals produced are identified by microprobe and powder X-ray diffraction analysis. It is shown that in case of GdSe_(1.85) the crystal structure is typical for rare-earth polychalcogenide structures, but the unit cell represents metrically a previously unknown type.