Manometric method for the study of P-T-X diagrams

A new approach to a single crystals growth of the iron sulfide phases of definite structure and nonstoichiometry is developed and applied. This approach is based on the method of crystal growing from solution melts. This approach is based on the crystallization or recrystallization of iron sulfides from iron sulfide solutions in iron dihalide melts under fixed sulfur vapor pressure in the closed system in non-isothermal (two-temperature) conditions. It allows to regulate the composition and structure of the resulting iron sulphide. In particular, at a relatively low pressure (< 0.4 atm), pyrrhotite with a trigonal 3T structure is synthesized. At higher pressure pyrite β-FeS 2 is grown. Reaction scheme for the formation of iron sulphides based on the reversible oxidation of sulfur by iron dihalide is proposed and substantiated. On the base of the {pyrite + marcasite} -mixture annealing under the melts of the deepest eutectic compositions of KCl -FeCl 2 and NaCl -KCl -FeCl 2 systems, the instability of the marcasite phase regarding the pyrite one (at least, for T ≥ 340°C) was shown.

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“…-vary the phase composition and nonstoichiometry of these solids. Thus, let us introduce the K P # -value 23 for equation (1):…”

Section: +mentioning

confidence: 99%

The Iron Sulfides Crystal Growth from the Halide Melts

et al. 2018

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“…In earlier work, [16,17] the authors demonstrated the possibility of application of iodide transport to control the composition of low-volatility gallium selenides in the temperature range of 800 £ T £ 1000 K and pressure range of 3Â10 4 £ P £ 3Â10 5 Pa, that is, at the conditions when ternary compounds (for example, GaSeI [18] ) are not stable. To control composition of gallium selenides, the following nonisothermal closed system was used: [12] Sample at T 2 (GaSe or Ga 2 Se 3 single crystals)-Vapor GaI + GaI 3 -Charge at T 1 (pure Ga) (quartz ampoule in the twozone horizontal furnace as shown in Fig.…”

Section: Control Of the Composition For Low-volatility Gallium Selenidesmentioning

confidence: 99%

“…The partial pressures of saturated Ga and Se vapors (as well as of Ga 2 Se species) over solid gallium selenides are by several orders of magnitude smaller than the pressure of gallium iodides; [16] therefore, the presence of Ga, Se, and Ga 2 Se species in the vapor can be neglected, and the gas phase consists of two components, GaI and GaI 3 . Since, according to the assumption mechanical equilibrium is set over the whole system (Ñp = 0 [20] ), diffusion and heat transfer in subsystem 3 are irreversible current processes.…”

Section: Stationary State In a Transport Nonisothermal Systemmentioning

confidence: 99%

“…In earlier studies, [16,17] the values of j p were determined for different three-phase equilibrium states (two binary condensed phases in the Ga-S system plus vapor phase made of gallium iodides) (Table 1). Based on Eq 7, it is possible to calculate T 2 -T 1 projection of the T 2 -T 1 -x 2 diagram at a stationary state for the Ga-S-I gas-transport system.…”

Section: Stationary State In a Transport Nonisothermal Systemmentioning

confidence: 99%

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Composition Control of Low-Volatility Solids Through Chemical Vapor Transport Reactions. I. Theory of Selective Chemical Vapor Transport

Zavrazhnov

Зарцын

Наумов

et al. 2007

J Phs Eqil and Diff

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“…In earlier studies, using vapor-pressure measurements with a Bourdon gage [19,24], k p was determined for various three-phase equilibria (two binary condensed Ga-Se phases + gallium iodide vapor) in the Ga-Se-I system ( Table 1). The results, obtained under near-equilibrium conditions, were used to calculate, using relation (34), the T 2 -T 1 projection of the x 2 -T 2 -T 1 diagram for the condensed phases in a nonequilibrium steady state without mass transport in the vapor transport system in question.…”

Section: Thermodynamic Analysismentioning

confidence: 99%

Chemical vapor transport as a means of controlling the composition of condensed phases

et al. 2004

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A new method is proposed for controlling the composition (nonstoichiometry) of low-volatile inorganic compounds. The basic principle of the method is the introduction (or removal) of one of the components into the low-volatile compound using reversible selective chemical vapor transport (CVT). Theoretical analysis is used to identify the process parameters determining the direction of mass transport: source temperature T 1 , source composition x 1 , and sample temperature T 2 . Using nonequilibrium thermodynamics concepts, steadystate conditions are found under which mass transport ceases. A new type of phase diagram, x 2 -T 1 -T 2 , is proposed, which describes the state of CVT systems under steady-state conditions without mass transport. The CVT process is used to prepare GaSe crystals with different deviations from stoichiometry. The crystals are characterized using x-ray diffraction and cathodoluminescence spectroscopy. The stability regions of two GaSe polytypes in the T -x phase diagram are located. CVT is used to control the compositions of phases in the In-S system. The advantages of the CVT method are analyzed with application to control over the composition of inorganic compounds. S102 INORGANIC MATERIALS Vol. 40 Suppl. 2 2004 ZAVRAZHNOV et al .

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Manometric method for the study of P-T-X diagrams

Cited by 11 publications

References 19 publications

The Iron Sulfides Crystal Growth from the Halide Melts

The Iron Sulfides Crystal Growth from the Halide Melts

Composition Control of Low-Volatility Solids Through Chemical Vapor Transport Reactions. I. Theory of Selective Chemical Vapor Transport

Chemical vapor transport as a means of controlling the composition of condensed phases

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