New gadolinium polyselenide GdSe1.89(6) in the PbFCl matlockite structure type
L.N. Zelenina1,2, T.P. Chusova1, N.V. Podberezskaya1, I.V. Korol`kov1,2, D.A. Piryazev1,2
1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Novosibirsk National Research State University, Novosibirsk, 630090 Russia
Keywords: полиселениды гадолиния, термодинамическое моделирование, выращивание кристаллов газотранспортными методами, рентгенофазовый и рентгеноструктурный анализ, gadolinium polyselenides, thermodynamic simulation, crystal growth by nitrogen-transport methods, powder and single crystal X-ray diffraction analysis
Abstract
Optimal growth conditions for GdSe1.85 crystals are found by the thermodynamic simulation of the Gd-Se-I system. The obtained data are used to grow GdSe1.85 crystals by the transport method using iodine as a transport agent. The grown crystals are identified by microprobe and powder X-ray diffraction analyses. The structure is determined by the single crystal X-ray diffraction analysis and the composition is refined. The crystal structure is in general typical of the structures of REM polychalcogenides, however, the unit cell represents the metric type unknown previously: a = 4.0562(2), b = 8.1065(5), c = 9.2489(5) , a = 115.9990(10), b = 90.000(2), g = 89.9750(10), V = 273.34(3) 3, Z = 4, d calc = 7.659 g/cm3, space group Pb 11. The experimental material for the X-ray crystallographic analysis is obtained on an automated Bruker X8 APEX diffractometer (Мо K radiation, graphite monochromator, CCD detector resolution 10241024 pixel, distance to the detector L = 50 mm, rotation about the axis 15 min) by the standard procedure, 2274 measured reflections, out of them 1523 independent ( R (int) = 0.0352), R -factor [ I > 2s( I )] = 0.0517, R -factor (all measured) = 0.0694).
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