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6 AZERBAIJAN CHEMICAL JOURNAL № 3 2023 ISSN 2522-1841 (Online)
ISSN 0005-2531 (Print)
UDC 544.344.015.3: 546.5723/24
SURFACES OF CRYSTALLIZATION AND PHASE RELATIONS IN THE 6Ag2Se+AgsSiTe6^6Ag2Te+AgsSiSe6 RECIPROCAL SYSTEM
12 2 3
A.J.Amiraslanova , K.N.Babanly , S.Z.Imamaliyeva , E.I.Akhmedov , Yu.A.Yusibov1, M.B.Babanly2, 3
!Ganja State University 2M.Nagiyev Institute of Catalysis and Inorganic Chemistry, Ministry of Science and Education
of the Republic of Azerbaijan 3Baku State University
samira9597a@gmail.com
Received 06.12.2022 Accepted 31.01.2023
The paper presents the results of a study of phase equilibria in the 6Ag2Se+Ag8SiTe6^ 6Ag2Te+Ag8SiSe6 reciprocal system by DTA and XRD methods. The projection of the liquidus surface, isothermal sections at 300, 500, 1150 K, and some polythermal sections of the phase diagram are constructed. It is shown that the system is reversible-reciprocal. It is characterized by the formation of continuous high-temperature solid solutions along the Ag8SiSe6-Ag8SiTe6 (8) and Ag2Se-Ag2Te (a) boundary systems. It has been established that the liquidus surface of the reciprocal system consists of two fields of primary crystallization a- and 8-phases. These surfaces are delimited by a eutectic curve with monovariant equilibrium L^a+8. In the subsolidus part of the system, a complex interaction is observed associated with the polymorphism of the initial compounds and phases based on them.
Keywords: silver-silicon selenide, silver-silicon telluride, argyrodites, phase equilibria, reciprocal system, solid solutions, polymorphic transformation.
doi.org/10.32737/0005-2531-2023-3-6-17
Introduction
Complex chalcogenides based on copper and silver are in the sphere of attention of researchers as eco-friendly functional materials with thermoelectric, photoelectric, optical, and other properties and can be used in medicine, alternative energy devices, and other high-technology fields [1-8]. Of particular note is a series of papers published in recent years, which clearly show the effectiveness of synthetic analogs of some natural copper and silver chalcogenide minerals as eco-friendly thermoe-lectrics in the medium temperature range, as well as photovoltaic and electrode materials for solar energy converters [9-15].
Among the most intensively studied similar materials, one can note compounds of the argyrodite family with the general formula Ai8BivX6 (A* - Cu, Ag; BIV-Si, Ge, Sn; X - S,
Se, Te) and phases based on them [16-28]. According to the available data, many of these compounds have mixed ionic-electronic con-
ductivity, which makes them very promising for use in the fabrication of photoelectrode materials, electrochemical solar energy converters, ion-selective sensors, photoelectronchemical visualizers, ionistors, etc. In the opinion of the authors of [17, 19, 26, 27] works, the presence of mixed electron-ionic conductivity is one of the significant factors that positively affect their thermoelectric characteristics.
At the initial stage of development of new multicomponent materials, it is important to study phase equilibria in the corresponding systems and construct phase diagrams, which allow not only to establish the presence of new compounds or phases of variable composition but also to establish their character of formation, the region of primary crystallization and homogeneity, phase transformations, etc. [29-32]. To optimize the functional properties of known compounds, it is expedient to obtain solid solutions based on them. From this point
of view, of interest are systems that include compounds - structural or formula analogs [32-38].
To obtain new complex phases of variable composition based on silver chalcogenides with p2 elements, it is expedient to study phase equilibria in the corresponding quaternary systems, especially about their 2Ag2X + BX2 — 2Ag2X'- BX2 (I) h Ag2X-BX2-B'X2 (II) (B, B'
- Si, Ge, Sn; X, X' - S, Se, Te) stable concentration planes. Previously, in some papers, we presented the results of studying systems of pointed types [39-44].
This work is devoted to the study of phase equilibria in the 6Ag2Se+Ag8SiTe6— 6Ag2Te+Ag8SiSe6 (C) reciprocal system.
The initial compounds and boundary quasi-binary components of system C have been studied in several works.
Crystallographic data of the starting compounds of the system C are shown in Table.
Silver selenide, Ag2Se melts congruently at 1170 K and undergoes a polymorphic transformation at 401 K [52]. The low-temperature modification has a rhombic structure, while the high-temperature modification has a cubic structure [45, 46]. The Ag2Te compound also melts with an open maximum at 1233 K and has polymorphic transitions at 1075 and 418 K [48]. The low-temperature modification has a monoclinic structure, while the intermediate and high-temperature modifications have a cubic structure [47-49].
The Ag8SiSe6 melts congruently. In various papers [53-56], very different values of the melting point of this compound are given. The phase diagram presented in [18] does not indicate a certain temperature of the distectics
point, but only a possible melting temperature range (1203-1263 K).
According to the available literature data, the Ag8SiSe6 compound has at least 3 crystalline modifications. However, different authors give different data for modifications of this compound. Given the disagreement in the literature data on the melting point and crystallo-graphic data, we [50] undertook a reinvestigation of this compound. According to the data of this work, the compound melts at 1278 K and has polymorphic transitions at 315 and 354 K.
The Ag8SiTe6 melts congruently at 1143 K [53] and has two polymorphic transformations at 195 and 263 K [57].
The Ag2Se-Ag2Te system [58, 59] is quasi-binary and is characterized by the formation of a continuous series of substitutional solid solutions between high-temperature cubic modifications of the initial compounds. The liquidus and solidus curves have a minimum point at 37 mol % Ag2Te and 1108 K. A complex interaction occurs in the subsolidus part of the system, associated with the polymorphism of the initial compounds. The Ag2Se-SiSe2 system is quasi-binary and has a distectic-type phase diagram. The Ag8SiSe6 ternary compound forms eutectics with both binary compounds [53-56].
The Ag2Te-Ag8SiTe6 system is also quasi-binary and belongs to the eutectic type [53]. The fourth boundary system, Ag8SiSe6-Ag8SiTe6, was studied by us recently [50]. It was established that it is quasi-binary and characterized by the formation of a continuous series of substitutional solid solutions between HT-Ag8SiSe6 and Ag8SiTe6.
Crystallographic data of the initial compounds of the system C
Compound Syngony, lattice parameters, nm
RT-Ag2Se [46] Rhombic, (P212121), a=0,4333; b=0,7062; c=0,7764
HT-Ag2Se [45] Cubic, (Fm3m), a=0,4983
RT-Ag2Te [48] Monoclinic, P\21/c\a = 0.8058, b = 0.4468; c = 0.8977, a = 90, p = 123.04
IT-Ag2Te [49] Cubic, Im-3m, a = 0.529
HT-Ag2Te [47] Cubic, Fm3m a = 0.66433
LT-Ag8SiSe6 [50] Cubic, F-43m, a=1.0965
HT-Ag8SiSe6 [50] Cubic, P4232, a=1.0891
RT-Ag8SiTe6 [51] Cubic, a=1.1528(3)
Experimental part
To study phase equilibria in the system C, binary Ag2Se, Ag2Te, and ternary Ag8SiSe6 and Ag8SiTe6 compounds were synthesized. The synthesis was carried out by fusing stoichiometric amounts of high-purity elemental components (Alfa Aesar) in evacuated (~10 Pa) quartz ampoules at temperatures 30-50 K above the melting point of the corresponding compound. To obtain homogeneous Ag2Se and Ag2Te of stoichiometric composition, according to the recommendation [60], after synthesis, they were quenched from a temperature of 1100 K into cold water.
To avoid a reaction between silicon and the walls of the quartz ampoule, the inner walls of the tube were graphitized by the decomposition of toluene.
At the melting temperature of the Ag8SiSe6 compound, selenium has a high vapor pressure [61], which can lead to an explosion. With this in mind, the Ag8SiSe6 compound was synthesized in an inclined two-zone furnace. Stoichiometric amounts of elementary components were placed in a quartz ampoule ~13-15 cm long and ~1.5 cm in diameter. After evacuation and sealing, the ampoule was placed in a furnace. Two-thirds of the ampoule was in the furnace, and the rest part was outside the furnace. The furnace was heated to 1300 K. During heating, selenium evaporated and accumulated in the upper "cold" zone of the ampoule. To prevent the explosion of the ampoule due to overheating of the "cold" zone, the latter was cooled with water and the condensed selenium returned to the lower "hot" zone again. As the components interacted, the amount of selenium in the upper part of the ampoule decreased, which was observed visually. After the disappearance of selenium in the "cold" zone, the ampoule was completely placed in the furnace.
The Ag8SiTe6 compound was synthesized by direct interaction of elementary components at 1200 K in a single-zone furnace.
The individuality of the synthesized compounds was controlled by differential thermal analysis (DTA) and X-ray phase diffraction analysis (XRD). By interpreting the powder X-
ray diffraction patterns, the parameters of the crystal lattices were obtained, which are in agreement with the literature data for RT-modifications of synthesized compounds (Table). The obtained DTA and XRD data for ternary compounds are presented and described in detail in [50].
Alloys of the system were synthesized by fusing the initial compounds at 1300 K in various ratios in evacuated quartz ampoules. Then ampoules were annealed at 800 K for 500 h for homogenization and cooled in the off-furnace mode. Some samples after annealing were quenched by throwing ampoules into cold water.
The samples were studied by DTA (NETZSCH 404 F1 Pegasus system) and XRD (D8 ADVANCE powder diffractometer, Bruker, CuKa1).
Results and discussion
Combined processing of the set of the obtained experimental data and literature data on boundary quasi-binary systems [50, 53-56, 58, 59] made it possible to obtain a complete self-consistent scheme of phase equilibria in the investigated system.
In the text and Figures, the following designations of phases are accepted:
a - continuous solid solutions between HT- g2Se and HT-Ag2Te
a' - solid solutions based on RT-Ag2Se;
P', P'' - solid solutions based on IT-Ag2Te and RT-Ag2Te;
8 - continuous solid solutions between HT- Ag8SiSe6 and Ag8SiTe6 ;
s, s' - solid solutions based on IT-Ag8SiSe6 and LT-Ag8SiSe6.
Solid-phase equilibria diagram
Figure 1 shows a solid-phase equilibria diagram of the investigated system at 300 and 500 K. As can be seen, at 300 K, the interaction of solid solutions based on Ag8SiTe6 (8), RT-modifications of compounds Ag2Se (a'), Ag2Te (P'') as well as IT- and u LT- modifications of Ag8SiSe6 (s and s') leads to the formation in this system of seven two-phase fields a'+s', a'+s, a'+8, P'+8, a'+p'', s+s', and s+8 separated by three-phase regions a'+s+s', a'+s+8
and a'+P''+ô (Figure 1 a). Two-phase regions a'+P", s+s' and s+ô have the form of narrow bands along the corresponding boundary systems.
The isothermal section at 500 K has a less complex scheme of phase equilibria. A continuous series of ô-solid solutions forms with a and P''-phases wide two-phase (a+ô, P''+ô) and three-phase (a'+P''+ô) fields (Figure 1b).
All of the above-pointed phase regions were confirmed by the XRD data. For example, Figure 2 shows powder diffraction patterns of some alloys from some heterogeneous regions (Figure 1a, points 1-3). As can be seen, the diffraction pattern of sample 1 consists of a set of reflection lines of a' and s-phases and sample 2
consists of reflection lines of a' and ô-phases. The powder diffraction pattern of sample 3 clearly demonstrates its three-phase nature. Comparison of the diffraction patterns of samples 2 and 3 shows that the reflection angles of the ô-phase on them practically coincide and correspond to an alloy of composition 60 mol% Ag8SiTe6 in the Ag8SiSe6-Ag8SiTe6 boundary system [50]. This shows that the vertex ô in the a'+P''+ô elementary triangle corresponds to the composition of 60 mol% Ag8SiTe6, and sample 2 is located near the border of the a'+ô and a'+P''+ô regions. Thus, the presented XRD data are in good agreement with the solid-phase equilibria diagram при 300 К.
40 60
mol%
a) b)
Fig.1. Diagram of solid-phase equilibria of the system C at 300 K.
Fig.2. Powder diffractograms of alloys 1-3 indicated in Fig.1.
Liquidus surface
The liquidus surface (Figure 3) consists of two area of the primary crystallization phase. Field (1) refers to the a-phase, and field (2) corresponds to the primary crystallization of the 8-phase. These areas of primary crystallization are delimited by the eutectic curve, which is characterized by a monovariant equilibrium Lo-a+8 (e1e2 curve, 1125-1103 K) (1) The curve emerging from the minimum point M on the liquidus and solidus curves of
the a-phase disappears without reaching the eutectic curve e1e2.
Despite the rather simple picture of the liquidus surface projection, this system is characterized by a complex pattern of phase relations in the subsolidus part. For a visual demonstration of the processes of crystallization from the melt and phase transformations in the subsolidus region of the system C, some polythermal sections of the phase diagram are plotted.
6 Ag2Se M 6 Ag,Te
Fig.3. Projection of the liquidus surface of the system C. Fields of primary phase crystallization: 1- a; 2 - 8. Dashed lines - studied polythermal sections.
Polythermal sections
Below are 3 vertical sections of the phase diagram, which are considered in the context of the projection of the liquidus surface (Figure 3), and solid-phase equilibria diagrams at 300 and 500 K (Figure 1) are presented.
Section 6Ag2Se-Ag8SiTe6 (Figure 4). This section passes through the fields of primary crystallization of a- and S-phases. At the point of intersection of the liquidus curves (~35 mol% Ag8SiTe6, 1120 K), the a + S eutectic mixture crystallizes from the melt. Below the liquidus curves, this monovariant process covers almost the entire range of compositions of this section. Crystallization is completed by reaction (1) and a+S two-phase region is formed.
During the interpretation of DTA data in the subsolidus part of this and subsequent poly-thermal sections, the data on phase equilibria in the Ag2Se-Ag2Te [51] and Ag8SiSe6-Ag8SiTe6 [50] boundary systems were taken into account.
In the subsolidus of the said polythermal section, several non- and monovariant processes take place, associated with the polymorphism of Ag2Se, Ag2Te, and Ag8SiSe6 compounds and the formation of solid solutions based on their various crystalline modifications. The formation of a- and a'- solid solutions is accompanied by
an increase in the phase transition temperature from 397 K to 420 K, at which the invariant reaction a+P'^a'+S occurs. During the formation of P' and P''-solid solutions based on IT- and LT-modifications of Ag2Te, the phase transition temperature decreases to 380 K, at which the eutectoid equilibrium P'^a'+P''+S is established in the composition range ~60-70 mol% Ag8SiTe6.
We did not detect any thermal effects on the DTA curves that could be attributed to polymorphic phase transitions based on Ag8SiSe6. Taking into account the data [50] on the Ag8SiSe6-Ag8SiTe6 boundary system, these phase regions in Figure 4 are marked with dotted lines.
Ag8SiSe6-6Ag2Te section (Figure 5). The liquidus of this section consists of two curves. In the range of compositions 0-43 mol% Ag8SiSe6, the a-phase primarily crystallizes from the melt, while in the region of the richer Ag8SiSe6, the S-phase is primarily crystallizes. Below the liquidus, as in the above section (Figure 4), crystallization proceeds according to the monovariant eutectic reaction (1) and ends with the formation of a+S two-phase mixture. Other equilibria reflected in the T-x diagram of this section are qualitatively similar to the above-considered polythermal section (Figure 4).
Fig.4. Polithermal section 6Ag2Se-Ag8SiTe6of the phase diagram of the system C
mol%
Fig.5. Polithermal section Ag8SiSe6-6Ag2Te of the phase diagram of the system C
Section [A]-[B] (Figure 6). Here [A] and [B] are alloys of the 6Ag2Se-Ag8SiSe6 and 6Ag2Te-Ag8Si|Te6 boundary systems with component ratios of 1:3. This section is completely located in the region of primary crystallization of the S-phase. The character of phase equilibria below the liquidus is qualitatively similar to Figure 4 and is described in detail above.
Isothermal section of the phase diagram at 1150 K
This section (Figure 7) of the volumetric phase diagram of the system C were built by us based on the projection of the liquidus surface
13
(Figure 3) and the above-described polythermal sections (Figures 4-6).
The section reflects the equilibrium of the melt with the 5-phase with compositions <70 mol% Ag8SiTe6, as well as a-solid solutions rich in selenium and tellurium. The directions of con-nodes in the two-phase fields L+a and L+5 make it possible to choose the compositions of solution-melts for growing the monocrystals a- or 5-phase with given compositions. For example, a melt of composition "l" which is in tie line with the 5-phase of composition "s" can be used for growing its crystals by the direct crystallization.
[A] ™ mol% w "" [B]
Fig.6. Polihtermal section [A]-[B] of the phase diagram of the system C
Fig. 7. Isothermal section of the phase diagram of the system C at 1150 K
Comparison of the above polythermal and isothermal sections of the phase diagram of the system C with each other, as well as with the projection of the liquidus surface (Figure 5) and diagrams of solid-phase equilibria in the subsolidus part (Figure 3) shows their mutual consistency.
Conclusion
Thus, in the presented work, a complete scheme of phase equilibria in the 6Ag2Se+ Ag8SiTe6o-6Ag2Te+Ag8SiSe6 reciprocal system was obtained, including some vertical and isothermal sections of the phase diagram, as well as the liquidus surface projection. It is established that this system is reversible-reciprocal, the liquidus consists of two surfaces corresponding to the primary crystallization of the a-and 5-phases. Crystallization, depending on the composition, is completed in the 1125-1105 K temperature range by a monovariant eutectic reaction Loa+5 with the formation of a+5 two-phase mixture. At temperatures below 1063 K, polymorphic phase transitions based on the starting compounds are observed, which leads to a complication of the phase relations and the formation of several two- and three-phase regions in the phase diagram.
The obtained data on phase equilibria can be used for the synthesis and crystals growth of the identified phases of variable composition -potential thermoelectric and ion-conducting materials.
Acknowledgments:
The work was supported by the Azerbaijan Science Foundation, Grant No AEF-MCG-2022- 1(42)- 12/10/4-M-10
References
1. Applications of Chalcogenides: S, Se, and Te / Ed. by Ahluwalia G.K. Springer, 2016. 461 p.
2. Chalcogenides: Advances in Research and Applications / Ed. by Woodrow P. Nova, 2018. 111 p.
3. Chalcogenide. From 3D to 2D and Beyond / Ed. by Liu X., Lee S., Furdyna J.K., Luo T., Zhang Y.-H. Elsevier, 2019. 385 p.
4. Scheer R., Schock H.-W. Chalcogenide Photo-voltaics: Physics, Technologies, and Thin Film Devices. Wiley-VCH, 2011. 384 p.
5. Alonso-Vante N. Chalcogenide Materials for Energy Conversion: Pathways to Oxygen and Hydrogen Reactions. Springer, 2018. 226 p.
6. Babanly M.B., Yusibov Yu.A., Abishev V.T. Ternary chalcogenides on the base of copper and silver (In Russian). Baku: BGU, 1993. 342 p.
7. Nieves L.M., Mossburg K., Hsu J.C., Maidment A.D.A., Cormode D.P. Silver chalc-
ogenide nanoparticles: a review of their biomedical applications. Nanoscale. 2021. V. 13. P. 19306-19323.
8. Mitra D., Kang E.-T., Neoh K.G. Antimicrobial Copper-Based Materials and Coatings: Potential Multifaceted Biomedical Applications. ACS Appl. Mater. Interfaces. 2020. V. 12. № 19. P. 2115921182. https://doi.org/10.1021/acsami.9b17815
9. Mikula A., Mars K., Nieroda P., Rutkowski P. Copper Chalcogenide-Copper Tetrahedrite Composites - A New Concept for Stable Thermoelectric Materials Based on the Chalcogenide System. Materials (Basel). 2021. V.14. № 10. P.2635. doi: 10.3390/ma14102635
10. Tee S.Y., Ponsford D., Lay Ch.E., Wang X., Wang X., Neo D.C.J., Wu T., Thitsartarn W., Yeo J.C.C., Guan G., Lee T.-C., Han M.-Y. Thermoelectric Silver-Based Chalcogenides. Adv. Sci. 2022. V. 9. № 36. P. 204624/135. 10.1002/advs.202204624
11. Kumar M., Meena B., Subramanyam P., Suryakala D., Subrahmanyam C. Emerging Copper-Based Semiconducting Materials for Photocathodic Applications in Solar Driven Water Splitting. Catalysts. 2022. V. 12. № 10. P. 1198. https://doi.org/10.3390/catal12101198
12. Mensah-Darkwa K., Ampong D.N., Agyekum E., de Souza F.M., Gupta R.K. Recent Advancements in Chalcogenides for Electrochemical Energy Storage Applications. Energies. 2022. V. 15. № 11. P. 4052. https://doi.org/10.3390/en15114052
13. Ramasamy K., Gupta R.K., Palchoudhury S., Ivanov S., Gupta A. Layer-Structured Copper Antimony Chalcogenides (CuSbSexS2-x): Stable Electrode Materials for Supercapacitors. Chem. Mater. 2015. V. 27. № 1. P. 379-386. https://doi.org/10.1021/cm5041166
14. Amrillah T., Prasetio A., Supandi A.R., Sidiq D.H., Putra F.S., Nugroho M.A., Salsabilla Z., Azmi R. Environment-friendly copper-based chalcogenide thin film solar cells: status and perspectives. Mater. Horiz. 2023. V. 10. P. 313339. https://doi.org/10.1039/D2MH00983H
15. Akhil S., Balakrishna R.G. CuBiSe2 Quantum Dots as Ecofriendly Photosensitizers for Solar Cells. ACS Sustainable Chem. Eng. 2022. V. 10. № 39. P. 13176-13184. https://doi.org/10.1021/ acssuschemeng. 2c04333
16. Lin S., Li W., Pei Y. Thermally insulative thermoelectric argyrodites. Mater. Today. 2021. V. 48. P. 198-213. https://doi.org/10.1016/ j.mattod.2021.01.007
17. Schwarzmüller S., Souchay D., Günther D., Gocke A., Dovgaliuk I., Miller S.A., Snyder G.J., Oeckler O. Argyrodite-Type Cu8GeSe6-xTex (0 < x < 2): Temperature-Dependent Crystal Structure and Thermoelectric Properties. Z.
Anorg. Allg. Chem. 2018. V. 644. № 2. P. 1915192. DOI: 10.1002/zaac.201800453
18. Jiang Q., Li S., Luo Y., Xin J., Li S., Li W., Zhao G., Yang J. Ecofriendly highly robust Ag8SiSe6-based thermoelectric composites with excellent performance near room temperature. ACS Appl. Mater. Interfaces. 2020. V. 12. № 49. P. 5465354661. https://doi.org/10.1021/acsami.0c15877
19. Fan Y., Wang G., Wang R., Zhang B., Shen X., Jiang P., Zhang X., Gu H., Lu X., Zhou X. Enhanced thermoelectric properties of p-type argyrodites Cu8GeS6 through Cu. J. Alloys Compd. 2020. V. 822. P. 153665. DOI: 10.1016/j.jallcom. 2020.153665
20. Charoenphakdee A., Kurosaki K., Muta H., Uno M., Yamanaka S. Ag8SiTe6: A New Thermoelectric Material with Low Thermal Conductivity. JJAP. 2009. V. 48. P. 011603/1-3. DOI 10.1143/JJAP.48.011603
21. Heep B.K., Weldert K.S., Krysiak Y., Day T.W., Zeier W.G., Kolb U., Snyder G.J., Tremel W. High electron mobility and disorder induced by silver ion migration lead to good thermoelectric performance in the argyrodite Ag8SiSe6. Chem. Mater. 2017. V. 29. № 11. P. 4833-4839. https://doi.org/10.1021/acs.chemmater.7b00767
22. Shen X., Xia Y., Yang C., Zhang Z., Li S., Tung Y., Benton A., Zhang X., Lu X., Wang G., He J., Zhou X. High Thermoelectric Performance in SulfideType Argyrodites Compound Ag8Sn(Si-xSex)6 Enabled by Ultralow Lattice Thermal Conductivity and Extended Cubic Phase Regime. Adv. Funct. Mater. 2020. V. 30. P. 2000526/1-10. https://doi.org/10.1002/adfm.202000526
23. Semkiv I., Ilchuk N., Kashuba A. Photoluminescence of Ag8SnSe6 argyrodite. Low Temp. Phys. 2022. V. 48. № 1. P. 12. https://doi.org/ 10.1063/10.0008957
24. Brammertz G., Vermang B., ElAnzeery H., Saha-yaraj S., Ranjbar S., Meuris M., Poortmans J. Fabrication and characterization of ternary Cu8SiS6 and Cu8SiSe6 thin film layers for optoelectronic applications. Thin Solid Films. 2016. V. 616. P. 649-654. https://doi.org/10.1016/j .tsf. 2016.09.049
25. Yeh L.-Y., Cheng K,-W. Modification of Ag8SnS6 Photoanodes with Incorporation of Zn Ions for Photo-Driven Hydrogen Production, Catalysts. 2021. V. 11. № 3. P. 363. https:// doi.org/10.3390/catal11030363
26. Li W., Lin S., Ge B., Yang J., Zhang W., Pei Y. Low Sound Velocity Contributing to the High Thermoelectric Performance of Ag8SnSe6. Adv. Sci. 2016. V. 3. № 11. P. 1600196. https:// doi.org/10.1002/advs.201600196
27. Weldert K.S., Zeier W.G., Day T.W., Panthofer M., Snyder G.J., Tremel W. Thermoelectric transport in Cu7PSe6 with high copper ionic
mobility. JACS. 2014. V. 136. P. 12035-12040. https://doi.org/10.1021/ja5056092
28. Sardarly R.M., Ashirov G.M., Mashadiyeva L.F., Ali-yeva N.A., Salmanov F.T., Agayeva R.Sh., Ma-medov R.A., Babanly M.B. Ionic conductivity of the Ag8GeSe6 compound. Mod. Phys. Lett. B. 2022. V. 36. № 32. P. 2250171. https://doi.org/10.1142/ S0217984922501718
29. West D.R.F. Ternary Phase Diagrams in Materials Science. 3rd Edition. CRC Press, 2019. 236 p.
30. Saka H. Introduction To Phase Diagrams In Materials Science And Engineering. World Scientific Publishing Company, 2020. 188 p.
31. Babanly M.B., Mashadiyeva L.F., Babanly D.M., Imamaliyeva S.Z., Tagiev D.B., Yusibov Y.A. Some issues of complex investigation of the phase equilibria and thermodynamic properties of the ternary chalcogenide systems by the EMF method. Russ. J. Inorg. Chem. 2019. V. 64. № 13. P. 16491671. DOI: 10.1134/S0036023619130035
32. Imamaliyeva S.Z. Phase diagrams in the development of thallium-REE tellurides with Tl5Te3 structure and multicomponent phases based on them. Condensed Matter and Interphases, 2018, v. 20. № 3. P. 332-347. https://doi.org/ 10.17308/ kcmf.2018.20/570
33. Imamaliyeva S.Z., Mamedov A.N., Babanly M.B. Modeling the phase diagram of the Tl9GdTe6-Tl4PbTe3-Tl9BiTe6 system. New Mater. Compd. Appl. 2021. V. 5. № 2. P. 79-86
34. Imamaliyeva S.Z., Alakbarzade G.I., Gasymov V.A., Babanly M.B. Solid-phase equilibria diagram of the Tl2Te-TlTbTe2-TlSbTe2 system. New Mater. Compd. Appl. 2020. V. 4. № 2. P. 99-107
35. Imamaliyeva S.Z., Alakbarzade G.I., Mamedov A.N., Babanly M.B. Modeling the phase diagrams of the Tl9SmTe6-Tl4PbTe3 and Tl9SmTe6-Tl9BiTe6 systems. Azerb. Chem. J. 2020. V. 4. P. 12-16. DOI: 10.32737/0005-2531-2020-4-12-16
36. Mammadov F.M., Amiraslanov I.R., Efendiyeva N.N., Imamaliyeva S.Z. Phase diagrams of the FeGa2S4-FeIn2S4 and FeS-FeGaInS4 systems. Chem. Prob. 2019. № 1. P. 58-65. DOI: 10.32737/2221-8688-2019-1-58-65
37. Imamaliyeva S.Z., Alakbarzade G.I., Salimov Z.E., Izzatli S.B., Jafarov Ya.I., Babanly M.B. The Tl4PbTe3-Tl9GdTe6-Tl9BiTe6 isopleth section of the Tl-Pb-Bi-Gd-Te system. Chemical Problems. 2018. № 4. P. 496-504.
38. Imamaliyeva S.Z., Mekhdiyeva I.F.,Gasymov V.A., Babanli M.B. Phase equilibria in the Tl5Te3-Tl9BiTe6-Tl9TmTe6 section of the Tl-Bi-Tm-Te quaternary system. Materials Research. 2017, V. 20. P.1057-1062. DOI:10.1590/1980-5373-mr-2016-0894.
39. Alverdiyev I.J., Aliev Z.S., Bagheri S.M., Mashadiyeva L.F., Yusibov Y.A., Babanly M.B. Study
of the 2Cu2S+GeSe2^Cu2Se+GeS2 reciprocal system and thermodynamic properties of the Cu8GeS6-xSex solid solutions. J. Alloys Compd. 2017. V. 691. P. 255-262. D01:10.1016/ J. JALLCOM.2016.08.251
40. Aliyeva Z.M., Bagheri S.M., Aliev Z.S., Alverdiyev I.J., Yusibov Y.A., Babanly M.B. The phase equilibria in the Ag2S-Ag8GeS6-Ag8SnS6 system. J. Alloys Compd. 2014. V. 611. P. 395400. https://doi.org/10.1016/jjallcom.2014.05.112
41. Aliyeva Z.M., Bagheri S.M., Alverdiyev I.J., Yusibov Y.A., Babanly M.B. Phase equilibria in the quasi-ternary system Ag2Se-Ag8GeSe6-Ag8SnSe6. Inorg. Mater. 2014. V. 50. № 10. P. 981-986. DOI: 10.1134/S002016851410001X
42. Alverdiyev I.J., Bagheri S.M., Aliev Z.M., Yusibov Yu.A., Babanly M.B. Phase equilibria in the Ag2Se-GeSe2-SnSe2 system and thermos-dynamic properties of the solid solutions Ag8Gei_ xSnxSe6. Inorg. Mater. 2017. V. 53. № 8. P. 886896. DOI: 10.1134/S0020168517080027
43. Mashadieva L.F., Alieva Z.M., Mirzoeva R.Dzh., Yusibov Yu.A., Shevel'kov A.V., Babanly M.B. Phase Equilibria in the Cu2Se-GeSe2-SnSe2 System. Russ. J. Inorg. 2022. V. 67. № 5. P. 670682. https://doi.org/10.1134/S0036023622050126
44. Amiraslanova A.J., Mammadova A.T., Imam-aliyeva S.Z., Alverdiyev I.J., Yusibov Yu.A., Babanly M.B. The 6Ag2Se+Ag8GeTe6^ 6Ag2Te+ Ag8GeSe reciprocal system. Russian Journal of Inorganic Chemistry, 2023, V.68. №8. P.1054-1064. DOI: 10.1134/S0036023623601046
45. Oliveria M., McMullan R.K., Wuensch B.J. Single crystal neutron diffraction analysis of the cation distribution in the high-temperature phases a-Cu2-xS, a-Cu2-xSe, and a-Ag2Se. Solid State Ion. 1988. V. 28-30. P. 1332-1337.
46. Wiegers G.A. The crystal structure of the low-temperature form of silver selenide. Am. Mineral. 1971. V. 56. P. 1882-1888.
47. Schneider J., Schulz H. X-ray powder diffraction of Ag2Te at temperatures up to 1123 K. Z. Kristallogr. 1993. V. 203. P. 1-15.
48. Van Der Lee A., De Boer J.L. Redetermination of the Structures of Hessite, Ag2Te-III. Acta Crystallogr. C. 1993. V. 49. P. 1444-1446.
49. Frueh A.J. Jr. The use of zone theory in problems of sulfide mineralogy. Part III: polymorphism of Ag2Te and Ag2S. Am. Mineral. 1961. V. 46. P. 654-660.
50. Amiraslanova A.J., Babanly K.N., Imamaliyeva S.Z., Alverdiyev I.J., Yusibov Yu.A., Babanly M.B. Phase equilibria in the Ag8SiSe6- Ag8SiTe6 system and characterization of solid solutions Ag8SiSe6-xTex. Appl. Chem. Eng. 2023. V.6. №2. P.1-9. doi: 10.24294/ace.v6i2.2162
51. Amiraslanova A.J., Babanly K.N., Imamaliyeva S.Z., Alverdiyev I.J., Yusibov Yu.A. Phase
relations in the Ag8SiS6-Ag8SiTe6 system and characterization of solid solutions. Azerb.Chem.J., 2023. №2. P. 169-177. doi.org/10.32737/0005-2531-2023-2-169-177
52. Binary alloy phase diagrams / Ed. by Massalski T.B. ASM International, Materials Park, Ohio, 1990. V. 3. 3589 p.
53. Gorochov O. Les composés Ag8MX6 (M= Si, Ge, Sn et X= S, Se, Te). Bull. Soc. chim. Fr. 1968. V. 101. P. 2263-2275.
54. Hofmann A.M. Silver-Selenium-Silicon, Ternary Alloys, VCH 2, 1988. P. 559-560.
55. Venkatraman M., Blachnik R., Schlieper A. The phase diagrams of M2X-SiX2 (M is Cu, Ag; X is S, Se). Thermochim. Acta. 1995. V. 249. P. 13-20. https://doi.org/10.1016/0040-6031(95)90666-5
56. Piskach L.V., Parasyuk O.V., Olekseyuk I.D., Romanyuk Y.E., Volkov S.V., Pekhnyo V.I. Interaction of argyrodite family compounds with the chalcogenides of II-b elements. J. Alloys
Compd. 2006. V. 421. P. 98-104. https:// doi.org/10.1016/jjallcom.2005.11.056
57. Boucher F., Evain M., Brec R. Single-Crystal Structure Determination of y-Ag8SiTe6 and Powder X-ray Study of Low-Temperature a and ß Phases. J. Solid State Chem. 1992. V. 100. P. 341-355. https://doi.org/10.1016/0022-4596(92)90109-9.
58. Aramov N., Odin I., Boncheva Mladenova Z. Study of the silver selenide-silver telluride system. Thermochim. Acta. 1977. V. 20. P. 107-113.
59. Hofmann Amtenbrink M. Silver-Selenium-Tellurium. Ternary Alloys, VCH. 1988. V. 2. P.567-568.
60. Glazov V.M., Burkhanov A.S., Saleeva N.M. On the method of obtaining single-phase copper and silver chalcogenides. Izv. Academy of Sciences of the USSR, Inorg. mater., 1977. V. 13. №. 5. P.917-918 [In Russian].
61. Emsley. The Elements. 3rd Edition, 1998. 300 p.
QARSILIQLI 6Ag2Se+Ag8SiTe6o6Ag2Te+Ag8SiSe6 SÎSTEMÎNDO KRlSTALLA§MA SOTHLORl
УЭ FAZA TARAZLIQLARI
A.C.0miraslanova, KN.Babanh, S.ZJmamaliyeva, E.LOhmadov, Yu.0.Yusibov, M.B.Babanli
Maqalada 6Ag2Se+Ag8SiTe6^6Ag2Te+Ag8SiSe6 qarçiliqli sisteminda faza tarazliqlannin DTA va RFA usullari ils tadqiqinin naticalari taqdim olunur. Sistemin likvidus sathinin proyeksiyasi, faza diaqraminin 300, 500, 1150 K-da izotermik kasiklari va bazi politermik kasiklari qurulmuçdur. Gôstarilmiçdir ki, sistem dônar-qarçiliqlidir va Ag8SiSe6-Ag8SiTe6 (5) va Ag2Se-Ag2Te (a) sarhad sistemlari boyunca fasilasiz yuksaktemperaturlu bark mahlul siralarinin amala galmasila xarakteriza olunur. Sistemin likvidus sathi a- va 5-fazalarin ilkin kristallaçmasina uygun galan iki sahadan ibaratdir. Bu sahalar L^a+5 monovariant tarazligini aks etdiran evtektika ayrisi ila sarhadlanirlar. Subsolidusda ilkin birlaçmalarin va onlarin asasinda fazalarin polimorfizmi ila alaqadar olan murakkab qarçiliqli tasir muçahida olunur.
Açar sozlzr: gumu§-silisium selenidi, gumu§-silisium telluridi, arqiroditbr, faza tarazliqlari, qar§iliqli sistem, bark mahlullar, polimorf çevrilma.
ПОВЕРХНОСТИ КРИСТАЛЛИЗАЦИИ И ФАЗОВЫЕ РАВНОВЕСИЯ ВО ВЗАИМНОЙ СИСТЕМЕ
6Ag2Se+Ag8SiTe6o6Ag2Te+Ag8SiSe6
А.Дж.Амирасланова, К.Н.Бабанлы, С.З.Имамалиева, Э.И.Ахмедов, Ю.А.Юсибов, М.Б.Бабанлы
В работе представлены результаты исследования фазовых равновесий во взаимной системе 6Ag2Se+Ag8SiTe6^6Ag2Te+Ag8SiSe6 методами ДТА и РФА. Построены проекция поверхности ликвидуса, изотермические сечения при 300, 500, 1150 К и некоторые политермические сечения фазовой диаграммы. Показано, что система обратимо-взаимна и характеризуется образованием непрерывных рядов высокотемпературных твердых растворов вдоль граничных систем Ag8SiSe6-Ag8SiTe6 (5) и Ag2Se-Ag2Te (a). Установлено, что поверхность ликвидуса системы состоит из двух полей, отвечающих первичной кристаллизации a- и 5-фаз. Эти поверхности разграничены эвтектической кривой с моновариантным равновесием L-oa+5. В субсолидусной части системы наблюдается сложное взаимодействие, связанное с полиморфизмом исходных соединений и фаз на их основе.
Ключевые слова: селенид серебра-кремния, теллурид серебра-кремния, аргиродиты, фазовые равновесия, взаимная система, твердые растворы, полиморфное превращение.
