M. V. Moroz

Physical properties of glasses in the Ag2GeS3-AgBr system

Glasses have been prepared by quenching melts in the Ag2GeS3-AgBr system in a range of 0–53 mol % AgBr. The concentration dependences of density, microhardness, glass transition temperatures, and crystallization of alloys have been established. The conductivity of glasses has been investigated by the dc probe method in a range of 240–420 K. The models of the drift motion of silver and halogen ions have been proposed.

Synthesis and electrical conductivity of crystalline and glassy alloys in the Ag3GeS3Br-GeS2 system

We have studied the formation of crystalline and glassy alloys in the Ag3GeS3Br-GeS2 system (0–52 mol % GeS2; Ag3GeS3Br is a glass-forming phase of variable composition) and determined the crystallographic parameters of the Ag3.179(9)Ge1.474(5)S4Br alloy as the saturated solid solution of GeS2 in Ag3GeS3Br: sp. gr. P213, a = 10.16572(3) Å, Z = 4. The electrical conductivity of the crystalline and glassy alloys was measured in the temperature range 250–410 K by a dc probe technique. The current carriers in the alloys are silver cations and halogen anions. We obtained materials with superionic conductivity and proposed a model for conduction in the alloys.

Thermodynamic properties of the intermediate phases of a Ag-Te-AgBr system

Silver interaction in galvanic elements C|Ag|Ag3GeS3I|B|C with heterophase alloys of the system (C corresponds to current electrodes; B, to heterophase alloys of the Ag-Te-AgBr system; and Ag3GeS3I, to glassy alloy with pure ionic (Ag+) electroconductivity) was studied. Data on the EMF temperature dependence of galvanic elements are used to calculate the values of thermodynamic functions for α-Ag5Te3, β-Ag2Te, and α-Ag3TeBr phases in the standard state.

Measuring the thermodynamic properties of saturated solid solutions in the Ag2Te-Bi-Bi2Te3 system by the electromotive force method

The temperature dependence of the electromotive force (EMF) of Ag|AgI|glass Ag2GeS3|D galvanic elements (where Ag, D are galvanic element electrodes, D is equilibrium three-phase alloys in the Ag2Te-Bi-Bi2Te3 system, AgI|glass Ag2GeS3 is a two-layer membrane with purely ionic (Ag+) conductivity) is studied in the range of 490–550 K. Analytical equations are obtained for the temperature dependences of the Gibbs energies of the formation of saturated solid solutions of the Bi14Te6, Bi2Te, BiTe, and Bi2Te phases from elements in the Ag2Te-Bi-Bi2Te3 system. E(T) analytical equations are used to calculate the standardstate thermodynamic functions of saturated solid solutions of the Bi14Te6, Bi2Te, BiTe, and Bi2Te3 phases in the Ag2Te-Bi-Bi2Te3 system.

Ag0.225Ge0.260S0.515-AgBr glasses

Homogeneous glasses have been obtained in the composition range 1.0–9.6 mol % AgBr by quenching molten mixtures of Ag0.225Ge0.260S0.515 and AgBr. The density, microhardness, glass transition temperature, and crystallization temperature of the glasses have been determined, and their electrical conductivity has been measured in the range 270–400 K by a dc probe technique. All of the glasses have purely ionic (Ag+ and Br−) conductivity. The mechanisms of electrical and mass transport processes in the alloys are discussed.

Thermodynamic Properties of Magnetic Semiconductors Ag 2 FeSn 3 S 8 and Ag 2 FeSnS 4 Determined by the EMF Method

Phase equilibria and thermodynamics in the Ag2SnS3–SnS–Sn2S3–FeS system were investigated using differential thermal analysis, X-ray diffraction, and EMF methods. Determined phase relations were used to express the forming chemical reactions for compounds Ag2FeSn3S8 and Ag2FeSnS4. The forming chemical reactions were performed by applying electrochemical cells of the types: (–) C | Ag | Ag3GeS3I glass | Ag2FeSn3S8, SnS, Sn2S3, FeS | C (+) and (–) C | Ag | Ag3GeS3I glass | Ag2FeSnS4, SnS, Ag2FeSn3S8, FeS | C (+). Based on the measured EMF versus temperature relations, experimental thermodynamic data of the quaternary phases Ag2FeSn3S8 and Ag2FeSnS4 were derived for the first time.

Thermodynamic Properties of AgIn 2 Te 3 I and AgIn 2 Te 3 Br, Determined by EMF Method

Differential thermal analysis (DTA), X-ray diffraction (XRD), and electromotive force (EMF) are used to triangulate Ag–In–Te–I(Br) systems in the vicinity of compounds AgIn2Te3I and AgIn2Te3Br. The three-dimensional position of the AgIn2Te3I–InTe–Ag2Te–AgI and AgIn2Te3Br–InTe–Ag3TeBr phase areas with respect to the figurative points of silver is used to create equations of potential-determining chemical reactions. The potential-determining reactions are conducted in (−)C|Ag|Ag3GeS3I(Br) glass|D|C(+) electrochemical cells (ECCs), where C stands for inert (graphite) electrodes, Ag and D are ECC electrodes (D denotes alloys of one-, three-, and four-phase areas), and Ag3GeS3I and Ag3GeS3Br glasses are membranes with purely ionic Ag+ conductivity. Linear parts of the temperature dependences of the cell EMFs are used to calculate the standard integral thermodynamic functions of saturated solid solutions based on AgIn2Te3I and AgIn2Te3Br, and the relative partial thermodynamic functions of silver in the stoichiometric quaternary compounds.

High-temperature oxidation of bismuth- and antimony-based sulfosalts

ABSTRACT In this article, oxidation processes of Ag-Bi-Sb-based phases were investigated. Synthesized AgBiS2 and AgSbS2-Sb2S3-Sb samples were thermally analyzed in synthetic air by applying the simultaneous DSC-TGA analysis technique. The oxidation processes at PO₂=0.2 atm and T<1173 K were observed to take place in many-step sequence of various reactions with an overall reaction 2AgMeS2 + 5.5O2(g) ⇄ 2Ag + Me2O3 + 4SO2(g), where Me=(Bi,Sb). Oxidations of AgBiS2, Sb2S3, and AgSbS2 were observed to begin above 549±2K, 610±2K, and 733±2K, respectively. Furthermore, oxidation processes of AgBi3S5 and Ag3SbS3 were estimated, and thermodynamic functions for the overall oxidation reactions were calculated and discussed.

Phase Equilibria and Thermodynamics of Selected Compounds in the Ag–Fe–Sn–S System

Polythermal sections in the vicinity of the quaternary compounds Ag2FeSnS4 and Ag2FeSn3S8 have been modeled. The mechanism of formation of these quaternary compounds and their thermal stability have been investigated. Measurements of electromotive force allowed calculations of the standard thermodynamic functions ΔG°, ΔH°, and S° of the Ag2FeSnS4 and Ag2FeSn3S8 compounds. Based on calorimetric measurements, the enthalpies of phase transitions of the selected compounds were determined. Furthermore, the heat capacities of both quaternary compounds were estimated by applying different calculation methods. Thermodynamic properties of the quaternary compounds, which are regarded as functional magnetic materials, were analyzed and are discussed in detail.