Synthesis of chalcogenide and pnictide crystals in salt melts using a steady-state temperature gradient

Чареев, Д. А.; Волкова, О. С.; Герингер, Н. В.; Koshelev, A. V.; Некрасов, А. Н.; Osadchii, Valentin O.; Осадчий, Е. Г.; Filimonova, Olga

doi:10.1134/s1063774516030068

Cited by 32 publications

(19 citation statements)

References 19 publications

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“…The crystal growth experiments were performed as described in Chareev et al (2017) using (1) the gas transport method, and (2) the salt flux technique (KCl/NaCl eutectic mixture, Chareev, 2016, Chareev et al , 2016). In the gas transport method NH 4 Cl was used as a transport agent.…”

Section: Methodsmentioning

confidence: 99%

Substitution mechanisms in In-, Au-, and Cu-bearing sphalerites studied by X-ray absorption spectroscopy of synthetic compounds and natural minerals

Filimonova

Trigub

Tonkacheev

et al. 2019

MinMag

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Sphalerite is the main source of In – a ‘critical’ metal widely used in high-tech electronics. In this mineral the concentration of In is commonly correlated directly with Cu content. Here we use X-ray absorption spectroscopy of synthetic compounds and natural crystals in order to investigate the substitution mechanisms in sphalerites where In is present, together with the group 11 metals. All the admixtures (Au, Cu, In) are distributed homogeneously within the sphalerite matrix, but their structural and chemical states are different. In all the samples investigated In3+ replaces Zn in the structure of sphalerite. The In ligand distance increases by 0.12 Å and 0.09–0.10 Å for the 1st and 2nd coordination shells, respectively, in comparison with pure sphalerite. The In–S distance in the 3rd coordination shell is close to the one of pure sphalerite. Gold in synthetic sphalerites is coordinated with sulfur (NS = 2.4–2.5, RAu–S = 2.35 ± 0.01 Å). Our data suggest that at high Au concentrations (0.03–0.5 wt.%) the Au2S clusters predominate, with a small admixture of the Au+ solid solution with an Au–S distance of 2.5 Å. Therefore, the homogeneous character of a trace-element distribution, which is commonly observed in natural sulfides, does not confirm formation of a solid solution. In contrast to Au, the presence of Cu+ with In exists only in the solid-solution state, where it is tetrahedrally coordinated with S atoms at a distance of 2.30 ± 0.03 Å. The distant coordination shells of Cu are disordered. These results demonstrate that the group 11 metals (Cu, Ag and Au) can exist in sphalerite in the metastable solid-solution state. The solid solution forms at high temperature via the charge compensation scheme 2Zn2+↔Me++Me3+. The final state of the trace elements at ambient temperature is governed by the difference in ionic radii with the main component (Zn), and concentration of admixtures.

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Section: Methodsmentioning

confidence: 99%

Substitution mechanisms in In-, Au-, and Cu-bearing sphalerites studied by X-ray absorption spectroscopy of synthetic compounds and natural minerals

Filimonova

Trigub

Tonkacheev

et al. 2019

MinMag

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“…The chalcogenide charge is gradually dissolved in the hot end of the ampoule and precipitates in the form of single crystals near the cold end. After keeping for 3 weeks in the furnace, iron monochalcogenide platelike crystals were found directly at the salt meltsolid interface [1,2]. The chemical composition of the crystals was determined using a Tescan Vega II XMU scanning electron microscope equipped with an INCA Energy 450 energy-dispersive spectrometer; the accelerating voltage was 20 kV.…”

Section: Methodsmentioning

confidence: 99%

“…Its critical temperature, rather low in stoichiometric state, T C ≈ 9 − 11 K, could be substantially raised up to 15 K [1,2] by Te substitution, or up to 37 K by applied pressure [3], and reaches as high as 100 K in FeSe monolayer on SrTiO 3 substrate [4] (for a review, see [5]). Bandstructure calculations [6] showed several bands crossing Fermi level, and cylinder-like Fermi surface sheets, electron around M point, and hole around Γ point.…”

Section: Introductionmentioning

confidence: 99%

Direct evidence of two superconducting gaps in FeSe0.5Te0.5: SnS-Andreev spectroscopy and the lower critical field

et al. 2016

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We present direct measurements of the superconducting order parameter in nearly optimal FeSe0.5Te0.5 single crystals with critical temperature TC ≈ 14 K. Using intrinsic multiple Andreev reflection effect (IMARE) spectroscopy and measurements of lower critical field, we directly determined two superconducting gaps, ∆L ≈ 3.3 − 3.4 meV and ∆S ≈ 1 meV, and their temperature dependences. We show that a two-band model fits well the experimental data. The estimated electron-boson coupling constants indicate a strong intraband and a moderate interband interaction.

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“…CHEMICAL ELEMENTS Specific examples of growing crystals of different chemical compounds in salt melts at a steady-state gradient were considered in [12]. Some chemical elements can be transported and form crystals jointly with some group of elements, but they do not form crystals with elements of another group.…”

Section: Possibility Of Growing Crystals Of Materials Consisting Of Dmentioning

confidence: 99%

“…All salt mixtures described in [12] are convenient for growing crystals in a certain temperature range. All salts are dissolved in water and, therefore, can easily be separated from the crystals grown.…”

Section: Possibility Of Growing Crystals Of Materials Consisting Of Dmentioning

confidence: 99%

General principles of the synthesis of chalcogenides and pnictides in salt melts using a steady-state temperature gradient

Чареев

2016

Crystallogr. Rep.

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The possibilities of growing crystals of metals, alloys, chalcogenides, and pnictides in halide melts using a steady-state temperature gradient are analyzed. Halides of alkali metals and aluminum can be used as transport media. The choice is determined by the melting temperature of salt mixtures. A conducting contour can also be applied to increase transport efficiency. This technique of crystal growth is similar to the electrochemical method. To eliminate interference during migration, some elements can be isolated and forced to migrate through independent channels to the crystal formation region. The technique considered here makes it possible to grow crystals of necessary quality without special equipment; the small crystal sizes are sufficient for laboratory study.

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Synthesis of chalcogenide and pnictide crystals in salt melts using a steady-state temperature gradient

Cited by 32 publications

References 19 publications

Substitution mechanisms in In-, Au-, and Cu-bearing sphalerites studied by X-ray absorption spectroscopy of synthetic compounds and natural minerals

Substitution mechanisms in In-, Au-, and Cu-bearing sphalerites studied by X-ray absorption spectroscopy of synthetic compounds and natural minerals

Direct evidence of two superconducting gaps in FeSe0.5Te0.5: SnS-Andreev spectroscopy and the lower critical field

General principles of the synthesis of chalcogenides and pnictides in salt melts using a steady-state temperature gradient

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