Synthesis, growth and structural investigation of Сu<sub>7</sub>SiS<sub>5</sub>I, Ag<sub>7</sub>SiS<sub>5</sub>I single crystals and solid solutions on their base

Authors

  • А. І. Погодін Uzhhorod National University, Ukraine
  • М. Й. Філеп Uzhhorod National University, Ukraine
  • М. М. Лучинець Uzhhorod National University, Ukraine
  • О. О. Ямковий Uzhhorod National University, Ukraine
  • О. П. Кохан Uzhhorod National University, Ukraine
  • І. П. Студеняк Uzhhorod National University, Ukraine

DOI:

https://doi.org/10.24144/2415-8038.2018.43.9-14

Keywords:

Solid solutions, Synthesis, Growth, Difractogram, Phase diagram, Lattice parameter

Abstract

Purpose. This work is aimed at synthesis and cgrowth, X-ray investigation, study of the phase diagram and concentration behavior of lattice parameter and density of (Cu1-хAgx)7SiS5I solid solutions.

Methods. Alloys of Cu7SiS5I – Ag7SiS5I system were synthesized by means of direct one-temperature method from pre-synthesized Cu7SiS5I and Ag7SiS5I compounds. Growth of single crystals of (Cu1-хAgx)7SiS5I solid solutions was carried out by means of crystallization from a solution-melt. Interaction in Cu7SiS5I – Ag7SiS5I system was investigated by means of differential-thermal analysis (Pt/PtRh thermocouple, heating speed 700 K/h), X-ray phase analysis (DRON 4-07, emission CuKα, angle scan step 2Θ - 0.02 deg, exposition - 0.5 s) and densimetric methods.

Results. According to the results of the X-ray phase analysis, calculations of the parameters of the elementary cell of Cu7SiS5I and Ag7SiS5I compounds and based on them alloys were carried out. The diffraction patterns of Cu7SiS5I and Ag7SiS5I compounds are indexed in face-centered cubic lattice . The number and nature of the reflexes on the diffractograms of alloys containing 10-90 mol.% of Cu7SiS5I indicate that a continuous series of solid solutions is formed in the system. According to the results of differential-thermal analysis and X-ray phase analysis, a phase diagram of Cu7SiS5I - Ag7SiS5I system was constructed. It is characterized by the formation of unbounded a-solid solutions based on both compounds with a minimum on the liquidus curve (2nd type by Rozebom). The coordinates of the minimum point are 16 mol.% Cu7SiS5I, 1165 K. It is established that the compositional depenedences of the lattice parameter and density occur  with a slight deviation "upward" from the from linear dependence.

Conclusions. The synthesis and growth of single crystals of (Cu1-хAgx)7SiS5I solid solutions were carried out. Alloys of Cu7SiS5I – Ag7SiS5I system were synthesized by means of direct one-temperature method from pre-synthesized Cu7SiS5I and Ag7SiS5I compounds. Growth of single crystals of (Cu1-хAgx)7SiS5I solid solutions was performed by means of crystallization from a solution-melt. Interaction in Cu7SiS5I – Ag7SiS5I system was investigated by means of differential-thermal analysis, X-ray phase analysis and densimetric methods. The diffraction patterns of Cu7SiS5I and Ag7SiS5I compounds were indexed in face-centered cubic lattice . According to the results of X-ray diffraction studies, it was found that a continuous series of solid solutions is formed in Cu7SiS5I – Ag7SiS5I system. The phase diagram of Cu7SiS5I - Ag7SiS5I system is characterized by the formation of unbounded a-solid solutions based on both compounds with a minimum on the liquidus curve (2nd type by Rozebom) with the coordinates of the minimum point constituting 16 mol.% Cu7SiS5I, 1165 K. It is shown that the concentration changes of the lattice parameter and density observed with a slight deviation "upward" from the linear dependence.

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Published

2018-06-30

Issue

Vol. 43 (2018)

Section

Статті

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