The Synthesis of Crystals of Chalcogenides of K, Zr, Hf, Hg, and Some Other Elements in Halide Melts under Conditions of
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The Synthesis of Crystals of Chalcogenides of K, Zr, Hf, Hg, and Some Other Elements in Halide Melts under Conditions of Stationary Temperature Gradient D. A. Chareeva,b,c,*, O. S. Volkovad,b, N. V. Geringere, P. V. Evstigneevaf, N. A. Zgurskiye, A. V. Koshelevd,b,a, A. N. Nekrasova, V. O. Osadchiid,a, E. G. Osadchiia, and O. N. Filimonovaf a Institute
of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia b Institute of Physics and Technology, Ural Federal University, Yekaterinburg, 620002 Russia c Kazan Federal University, Kazan, 420008 Russia d Moscow State University, Moscow, 119991 Russia e State University “Dubna”, Dubna, 141980 Russia f Institute of Geology of Ore Deposits, Russian Academy of Sciences, Moscow, 119017 Russia *e-mail: [email protected] Received May 29, 2018; revised December 9, 2018; accepted December 11, 2018
Abstract—The growth of crystals of metals, alloys, chalcogenides, and pnictides in melts of alkali metal halides under conditions of stationary temperature gradient has been studied. The formation of crystals with participation of elements that were not considered in previous studies (mercury, zirconium, hafnium, germanium, sodium, potassium, rhenium, and osmium) is described. Mechanisms of element transport in salt melts are proposed. It is shown that most of crystals are obtained from ions in which necessary elements exist in most conventional oxidation states. DOI: 10.1134/S1063774519060038
INTRODUCTION Currently, crystals of metal chalcogenides (compounds containing S, Se, and Te) and pnictides (compounds with P, As, Sb, and Bi) have been intensively studied. The attention paid to these compounds is explained by their semiconductor and luminescence properties, which are of interest for the fundamental science, and the wide prospects of their application as superconductors, magnets, topological insulators, catalysts, and other functional materials. In addition, sulfides in nature are the main component of many polymetallic ores, which are one of the main sources of nonferrous metals. To explain the properties of these materials, it is necessary to carrying out experiments on high-quality chalcogenide and pnictide crystals. Gas transport and hydrothermal methods are widely used to grow chalcogenide and pnictide crystals. The flux method is also popular. It implies gradual cooling of a multicomponent melt, which rather often leads to the formation of zonal crystals. This drawback can be excluded by modifying the method as follows: the charge is first gradually dissolved in a chosen solvent and then diffuses to form a crystal in another part of the reaction vessel at a lower temperature. The temperature field at any point of the system barely changes with time. The fixation of crystal
growth temperature makes it possible to reduce to minimum the change in the activity of melt components and, therefore, minimize the fluctuations in the composition and properties of crystals grown. Despite the simplicity and good reproducibility,
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