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ISSN 2522-1841 (Online) AZERBAIJAN CHEMICAL JOURNAL № 1 2023 183
ISSN 0005-2531 (Print)
UDC 846.65:546.86.87.56.72.22
SYNTHESIS, GROWTH OF MONOCRYSTALS AND PROPERTIES OF THE COMPOUNDS OF PbLnCuS3 (Ln-La, Nd, Sm, Gd, Dy, Er) TYPE
O.M.Aliyev, D.S.Azhdarova, T.F.Maksudova, V.M.Ragimova, S.T.Bayramova
M.Nagiyev Institute of Catalysis and Inorganic Chemistry, Ministry of Science and Education of the
Republic of Azerbaijan
chemistry@science.az
Received 22.05.2022 Accepted 15.07.2022
Quaternary sulfides of the PbLnCuS3 type (Ln-La, Nd, Sm, Gd, Dy, Er) have been obtained either by melting the elements or through furnace charge, 2PbS+Cu2S+Ln2S3 in a graphite crucible placed in a sealed quartz ampoule at a temperature of 1200-1275 K. Monocrystals of PbSmCuS3 and PbGdCuS3 have been grown by mineralization method. The study of X-ray analysis showed that compounds of PbLnCuS3 type crystallize in the orthorhombic singony (a=8.26^8.20; b=8.84^8.80; c=7.96^7.9A, space group Pmn2j). In a series of PbLnCuS3 compounds, the phenomenon of morphotropy manifests itself, which flows from the exchange of the structural type (PbCuSbS3 ^KZrCuSe3 ^ Eu2CuS2), i.e. when the radius of the cation Ln changes. Their standard thermodynamic functions have been calculated and the temperature dependences of the magnetic susceptibility have been measured.
Keywords: sulfosalt, phase diagrams, crystal structure, lattice parameter, thermodynamic functions, magnetic susceptibility.
doi.org/10.32737/0005-2531-2023-1-183-190
Introduction
As is known, in recent years it has been practicing to obtain new multifunctional compounds with modified compositions based on known basic structures. In particular, it has been established that any phase with the same crystal structure and the same ratio between number of valence electrons and the number of atoms as in a known compound has similar properties [1-8].
The simplest type of obtaining the derivative of compound is the substituting one of the elements included in the composition of the known related elements of the same group in the periodic system.
The presence of complex sulfide ions of s-, d-, 4f elements in the cationic sublattice provides basis for the formation of the properties of compounds with the required quantitative values.
The aim of this work is the synthesis, growth of monocrystals and study of some fundamental properties of the PbLnCuS3 (Ln-La,
Nd, Sm, Gd, Dy, Er) type compounds - analogs of the mineral bournonite PbCuSbS3.
The PbCuSbS3 compound is found in nature as a mineral [9]. A structural study of bournonite has been carried out in [10]. It has been established that its structure is similar to that of antimonite (stibnite) [11, 12] and aikinite [13-16]. The diagonals of bournonite correspond to positions a and b of the antimonite, Pb and Sb occupy alternately the place of Sb in the antimonite lattice instead of Sb, which is twice as much in comparison with antimonite.
In the structure, Cu atoms are located in the tetrahedral planes of the lattice, which compensates the replacement of one Sb atom by lead atoms.
In recent years, the synthetic analogues of berthierite FeSb2S4 [19, 20], cosalite Pb2Bi2S5 [6, 21], krupkaite CuPbBi3S6 [22, 23], naffieldite [4, 24, 25] and aikinite CuPbBiS3 have been synthesized and studied their physi-cochemical characteristics [26, 27].
The structural features of synthetic analogues of the mineral bournonite have been obtained and studied by substituting lead atoms with Eu and Yb atoms [28-34]. It has been es-
tablished that in this case the structural type remains and synthesized compound crystallizes in the orthorhombic singony.
It is known that the coordination number of lanthanides in complex sulfosalts varies from 6 to 9 [35] and mainly have coordination poly-hedra in the form of octahedrons, trigonal prisms, mono-, bi- and tri-capped trigonal prisms. Taking into account the similar coordination sorroundings of lead, antimony, and rare earth elements, we can assume the possible existence of new classes of quaternary sulfosalts substituting antimony atoms in the structure of bournonite PbCuSbS3 with atoms of trivalent lanthanides.
Experimental part
Quaternary sulfosalts of the PbLnCuS3 type have been obtained either by alloying the elements, or charging 2PbS+Cu2S+2Ln+3S in a graphite crucible, located in a sealed quartz ampoule. Powder mixtures of these compounds were kept in a sulfur atmosphere at a temperature of 1200 K for 5-7 h. The reaction products have been ground into powder in an agate mortar, pressed into tablets, then mixed in a quartz ampoule and pumped out. After synthesis, the prepared ampoules have been annealed at 1000-1050 K for 480-600 h, and then studied by the physicochemical analysis methods.
X-ray phase analysis (XRD) has been performed on a Bruker D2PHASER X-ray dif-fractometer (CuKa-radiation, Ni-filter), microstructural analysis (MSA) - on the MHM-7 microscope, and microhardness has been measured on the nMT-3M-branded microhardness tester. Differential thermal analysis (DTA) has been performed on HTP-70 and B^TA-marked Kurnakov's pyrometer.
Results and their discussion
Quaternary sulfosalts of PbLnCuS3 (Ln-La, Nd, Sm, Gd, Dy, Er) type are formed in the CuLnS2-Pb system.
Let's briefly dwell on the CuErS2-PbS system as an example constituted according to the data of the physicochemical analysis (Figure 1).
As is seen, the system is characterized by a complex interaction of the initial sulfides. The quaternary compound of the composition PbErCuS3 melting incongruently at 1276 K is formed at a components ratio of 1:1. The sul-fosalt PbErCuS3 forms a eutectic with lead sulfide. The coordinates of the eutectic point: 80 mol% PbS, T=1140 K. Solubility based on the initial components and the quaternary compound was practically not detected.
In the PbErCuS3-PbS system, PbErCuS3 and y-CuErS2 are in the equilibrium state in the concentration range of 50-100 mol% CuErS2 at the temperature below the peritectic decomposition of the PbErCuS3 phase. Phase transitions
a-CuErS2 ^ P-CuErS2 ^ y-CuErS2
occur at 1080 and 1205 K, respectively.
The PbErCuS3 compound is formed by the peritectic reaction L+PbS^PbErCuS3 at 1275 K. In the concentration range of 10-50 mol% PbS at the temperatures above 1530K, two-phase (L+Er2S3) and three-phase (L+Er2S3+CuErS2) regions are observed; therefore, the CuErS2-PbS system can be accepted as partially quasi-binary.
The phase diagrams of the CuLnS2-PbS systems were plotted according to the results of independent methods of physicochemical analyses that make it possible to accept them reliable.
Obtaining PbLnCuS3 compound in the PbS-Cu2S-Ln2S3 systems is correlated with significant differences in thus properties of element atoms as valence electrons, electronegativity of the elements (EN), ionic radii, which are Pb 6s2; EN 1.8; r(Pb+2)=1.26A ; Cu3d104s1; EN 1.93; r(Cu+)=0.98A; Ln 5d0-16s2; EN 1.271.48; r(Ln+3)=107=0,848A, respec-tively.
Quantitative differences between s- and d-, also 4f- elements are 12-42% in initial radii, 18-60% in electronegativities. The ratio of acid-base properties of simple sulphides should belong to their integral characteristics. PbS shows basic properties; Cu2S and Ln2S3 indicate acidic properties besides basic ones. It is known that the copper ion has very noticeable complex-
formation property, too. In this state, sulphosalt can belong to thio-type salts obtained from basic sulphide PbS and more acidic sulphides Cu2S and Ln2S3. An increase in acidic properties of Ln2S3 increases the thermodynamic stability of complex sulphides PbLnCuS3, which has been proved experimentally. The melting and decomposition points increase in the PbLnCuS3 sulphosalt series.
On the diffraction patterns of the samples annealed at 1000 K, the subsolidus part contains only reflections of the conjugated phases of PbPrCuS3 and the low-temperature modify-cation of a-CuErS2 or PbS+PbErCuSe3. Mono-crystals for structural analysis on the example of PbSmCuS3 and PbGdCuS3 have been grown by the mineralization method, i.e. by one of the options in directional crystallization at a temperature of 1050-1075K for a month.
185
One feature of the PbGdCuS3 compound should be noted. Directional crystallization of a stoichiometric melt without special additives formed ingots that have mostly hole conductivity. The result of a deviation from stoichiometry is possible due to the combination of volatile components. The ingot always contained an excess of copper, which dissolves in the compound in small amounts and provides p-type conductivity; therefore, any doping of the PbGdCuS3 compound during the growth of its crystals by the way of directional freezing occurs in the background of this phenomenon [35].
As a result of that, the monocrystals of PbSmCuS3 and PbGdCuS3 have been obtained with a size of 1.5x0.5 mm, sufficient for structural and optical studies (Figure 2).
Fig. 1. Phase diagram of the CuErS2-PbS system. • - data of DTA; x - data of HDTA.
Fig.2. Lauegrams of the PbSmCuS3 and PbGdCuS3 compounds.
The X-ray diffraction study showed that the PbLnCuS3 and PbNdCuS3 compounds crystallize in the orthorhombic singony and belong to the PbCuSbS3 structural type; the PbSmCuS3 and PbGdCuS3 compounds belong to the KZr-CuSe3 structural type, while the PbDyCuS3 and PbErCuS3 compounds belong to the Eu2CuS3 structural type.
Calculation of X-ray diffraction patterns of the obtained compounds and crystallographic data are shown in Table 1 and 2, respectively.
The magnetic susceptibilities of the PbSmCuS3, PbGdCuS3, and PbErCuS3 compounds have been measured in the temperature range 77-500 K. The results of the measurement are shown in Figure 3. As is seen from the figure, these compounds have paramagnetic properties and they transform into ferromagnetic states at temperatures below 150 K.
The changes in the nature of the chemical interaction in the PbS-Cu2S-Ln2S3 systems, as well as in the structural characteristics of the PbLnCuS3 compound occur in the regions of the REE, the position of which correlates with periodicity of 4f-electron shells-position, i.e. in the areas of crystallochemical instabilities Nd-Sm, Gd, Ho-Er. Internal periodicity in the CuLnS2-
PbS systems is determined in the form of a tetrad effect.
As is seen from the presented data, the isostructurality of the formulaic analogs of the sulfosalt of the PbLnCuS3 type does not apply to the entire series of rare earth elements; i.e. does not apparently correlate with the monotone change sequence in the ion radii of REE.
The formation of the corresponding structural types for complex REE sulfosalts is determined by a complex dependence on the composition, the ratio of anion and cation radii, with the difference in the structure of the electron shells of the metal (Pb), REE, and chalco-gen, which characterize the type of chemical bond and energy, the formation of various structures, as well as the conditions for obtaining. In a series of PbLnCuS3 (Ln=La-Er) compounds, morphotropies are manifested, consisting in the cancellation of the structural type (PbCuSbS3 ^ KZrCuSe3 ^ Eu2CuS3) during
3+
the change in the radius of the Ln3+ cation, as well as the shape of crystals (with an increase in the coordination number during the increase in radii); the volumes and parameters of the unit cell of isostructural compounds decrease with a change in rL3^.
Table 1. Interplanar distances, hkl, and intensities of lines unique to compounds of the PbLnCuS3 type
PbLaCuS3 PbSmCuS3 PbDyCuS3
Dexp., Ä Irel. hkl Dexp., Ä Irel. hkl Dexp., Ä Irel. hkl Dcalc.,Ä
5.728 1 101 3.892 2 100 8.649 2 101 8.058
4.809 2 111 3.742 2 110 6.449 4 002 6.451
4.422 3 020 3.519 4 111 5.151 1 200 5.150
4.129 5 200 3.370 1 120 4.030 2 202 4.026
3.985 10 002 3.318 6 040 3.940 4 010 3.942
3.742 6 210 3.194 4 121 3.536 2 111 3.540
3.330 1 112 3.030 2 112 3.361 6 012 3.363
3.060 7 220 2.810 4 122.131 3.222 10 004 3.226
2.951 5 030 2.566 4 004 3.196 6 112 3.198
2.861 6 202 2.532 2 132 1.126 1 210 3.130
2.749 10 300 2.402 6 123 2.902 1 013 2.905
2.722 6 212 2.210 4 060 2.820 3 212 2.816
2.649 7 003 2.184 4 150 2.580 10 400 2.575
2.495 2 311 1.950 10 200 2.538 8 311,401 2.538
2.430 5 113 1.934 2 134 2.154 4 410 2.156
2.370 3 032 1.920 1 210 2.130 2 412 2.126
2.300 3 231 1.908 1 201 2.041 1 412 2.045
2.273 5 132 1.888 2 211 1.970 10 020 1.970
2.009 6 330,401 1.868 3 220, 063 1.946 2 021 1.948
1.994 5 223 1.804 6 212 1.846 1 122 1.853
1.870 6 420 1.760 4 222 1.822 1 510 1.826
1.792 8 332 1.715 4 006 1.768 4 123,222 1.770
1.724 1 051 1.656 2 080 1.712 6 600 1.712
1.652 2 500 1.468 1 007 1.688 2 321,223 1.692
1.546 2 520 1.35 1 2 137 1.646 1 322 1.654
1.423 1 414 1.289 2 310 1.620 6 008 1.614
1.313 1 443 1.242 1 330 1.570 1 420 1.565
1.201 1 444 1.466 1 422 1.470
1.282 1 032 1.287
1.268 2 622 1.269
Table 2. Crystallographic and physicochemical data of the compound of PbLnCuS3 type
Compounds Structure type Space group Z Parameters of the cell, Ä V, Ä3 P, MPa d, g/cm3
a b c
PbLaCuS3 PbCuSbS3 Pmn2i 4 8.260 8.840 7.96 581.23 3100 5.76
PbNdCuS3 PbCuSbS3 Pmn2i 4 8.200 8.80 7.92 571.57 3200 5.90
PbSmCuS3 KZrCuSe3 Cmcm 4 3.90 13.28 10.30 5.33.50 3250 6.42
PbGdCuS3 Cmcm 4 3.860 13.24 10.26 524.35 3250 6.65
PbDyCuS3 Eu2CuS3 Pnma 4 10.30 3.94 12.90 523.52 2850 6.84
PbErCuS3 Pnma 4 10.26 3.90 12.86 514.58 2920 6.90
1 3
X"1, r/CM
50 40 30 20
10
10
20
30 T,K
40
50
60
Fig. 3. The temperature dependence of magnetic susceptibility of the PbSmCuSs (1), PbGdCuS3 (2) and PbErCuS3 (3) compounds.
Conclusion
Thus, according to the results of complex methods of physicochemical analyses, the phase diagrams have been plotted and the obtaining PbLnCuS3-type incongruently melting tetrahedral sulphosalts has been established. It has been established that morphotropy occurs besides formation of PbLnCuS3 (Ln=La —Er), that involve exchanging structure type in chang-
ing radius of the Ln the crystal shapes.
References
+3
cation and consequently
1. Wu Yuandong, Bensch Volfgang. K2Ln2As2S9 (Ln-Sm, Gd) the quaternary rare earth sulfo arsenate compounds . Inorgan. Chem.2009. V.18. No7. P.2729-2732.
2. Sikerina N.V., Solov'eva A.V., Toroshin E.N., Andreev O.V. Fazovye ravnovesiya v sisteme BaS-Cu2S-Gd2S3. ZHurn. Neorgan. Himii. 2007. T.52. № 12. C. 2099-2103.
3. Sikerina N.V., Andreyev O.V., Leven I.P. Interaction in the SrS-Cu2S-Ln2S3 (Ln=La- Nd) system.
J. Inorganic Materials. 2008. V.53. No3. P.455-459.
4. Aliev O.M., Agaeva R.M., Kasumov V.A. Sintez i rentgenograficheskoe issledovanie soedineniya Cu2LnSb3S7 (Ln=La, Nd). Izv. RAN. Neorganicheskie materialy. 2002. T.38. №7. S. 784-787.
5. Gasymov V.A., Gasymova G.N., Aliev O.M. Sintez i rentgenograficheskoe issledovanie analoga bert'erita FeSb2S4. Neorgan. materialy. 2004. T. 40. № 10. S. 1247-1248.
6. Aliev O.M., Gasymov V.A., Ismailova G.N. Sintez i rentgenograficheskoe issledovanie PbEu-Bi2S5 i PbYbBi2S5 analogov minerala kozalita. Azerb.him. zhurn. 2007. № 1. S. 116-122.
7. Rusajkina A.V. Struktura soedinenij EuLnCuS3 (Ln=La-Nd, Sm), fazovye diagrammy sistem Cu2S-EuS-Ln2S3, termohimicheskie charakteristiki i fa-zovyh prevrashchenij. Avtoref. diss. ... kand. him. nauk. Tyumenskij Gos. Un-t. 2011. 25 s.
8. Demchuk ZH.A. Fazovye ravnovesiya v sistemah Dy2S3-EuS, EuS-Dy2S3-Cu2S, ental'pii fazovyh prevrashchenij, struktura soedinenij tipa EuHoCuS3. Avtoref. Diss. ... kand. him. nauk. Tyumen: Tyumenskij Gos. Un-t. 2015. 29 s.
9. Kostov I., Minacheva-Stefanova N. Sul'fidnye mneraly. M.: Mir, 1984. 281 s..
2
3
10. Edenhoerter A., Nomacki W., Takeuchi V. Verfeinerung der kristallstructur von Bournonit [(SbSs)2. CuI2VPbVIIPbVI11 ] und von seligmannit [(AsS3)2/ CuI2VPbVIIPbI11 ]. Z. Kristallogr. 1970. V. 131. No1. P). 397-417.
11. Vang Huakeing, Su Kiaohui, Tang Aidong. Mie rawave synthesis of nanokristalline Sb2S3 and its electrochemical properties //Mater. Res. Bull. 202. V.56. No 7. P. 1357-1363.
12. Bayliss P., Nowacki W. Refinement of the structure of stibnite Sb2S3 //Z. Kristallogr. 1972. V.135. No 2. P. 308-315.
13. Ohmasa M., Nowacki W. A. redetermination of the crystal structure of aikinite (BiS2/S/CuIVPbVI1). Z. Kristallogr. 1970. V.132. No 1. P. 71-86.
14. Kohatsu I., Wuensch B.J. The crystal structure of aikinite, PbCuBiS3. Acta Crystallogr. 1971. V. 27. No 6. P. 1245-1252.
15. Harris D.C., Chen T.T. Crystal chemistry and reexamination on nomenclature of sulfosalts in the aikinite - bismuthinite series. Canad. Miner. 1976. V. 14. No1. P. 199-205.
16. Makovicky M. Representation of composition in the bismuthinite - aikinite series. Canad . Miner. 1978. V.16. No 2. P. 405-409.
17. Kohatsu I., Wuensch B.J. The crystal structure of gladite, PbCuBi3S6, a superstructure intermediate in the series Bi2S3-PbCuBiS3 (bismuthinite - aiki-nite). Acta Crystallogr. 1976. B. 32. No 11. P. 2401-2403.
18. Pobedimskaya E.A., Kaplunnik L.N., Petrova I.V. i dr. Kristallohimiya sul'fidov /Itogi nauki i tekhniki. Seriya Kristallohimiya. M.: Izd-vo AN SSSR. 1983. T.17. 164 s.
19. Aliev O.M., Azhdarova D.S., Ragimova V.M., Maksudova T.F. Sintez i fiziko-himicheskie svojstva lantansoderzhashchego analoga minerala bert'erita FeSb2S4 //ZHurn. Neorgan.himii. 2018. T.63. №3. S. 1-4.
20. Aliev O.M., Asadov M.M., Ajdarova D.S., Mamedova Sh.H., Ragimova V.M. Polythermal section FeSb2S4-FeSm2S4 of the FeS-Sb2S3-Sm2S3 system. J. Inorgan. Chem. 2018. V. 63. No6. P. 833-836.
21. Aliev O.M., Ismailova G.N. Sintez i fiziko-himicheskie svojstva soedineniya Eu2Bi2S5. Izv. Azerb. Gos. Pedagogicheskogo un-ta. Seriya estestv. nauk. 2006. № 2. S. 87-90.
22. Gasymov V.A., Gasimova G.N., Aliyev O.M. Synthesis and physical-chemical properties of the CuEuBi3S6. Chemical Problems. 2003. № 4. P. 74-76.
23. Aliev O.M., Ismailova G.N., Gasymov V.A., Ah-medova N.R. Sintez, vyrashchivanie mono-kristallov, strukturnye osobennosti i fiziko-himicheskie svojstva soedinenij proizvodnyj ot miner-
ala krupkaita. Izv. Azerb. Gos. Pedagogicheskogo un-ta. Seriya estestv. Nauk. 2007. №1. S. 69-75.
24. Aliev O.M., Ajdarova D.S., Agayeva R.M., Ragimova V.M., Gasymov V.A. Synthesis and study of synthetic analogues of nuffieldite mineral with rare earth elements. Reports NASA. 2015. V. LXXI. No 1. P. 42-46.
25. Aliev O.M., Ajdarova D.S., Agayeva R.M., Mamedov Sh.H., Ragimova V.M. Sintez i izu-chenie svojstv sinteticheskih analogov minerala naffil'dita s uchastiem redkozemel'nyh elementov. Kondensirovannye sredy i mezhfaznye granicy. Voronezh. Gos. Un-ta. Rossiya: 2022. 24(1). S. 3-10.
26. Aliev O.M., Azhdarova D.S., Ragimova V.M., Bajramova S.T. Izuchenie kvazitrojnoj sistemy Cu2S-PbS-Bi2S3 po razrezam CuBiS2-PbS, Bi2S3-PbCuBiS3, Cu2S-PbCuBiS3. Mezhdunard. Zhurnal prikl.i fundam. issledovanij. 2015. Ch.1. № 6. S. 465-468.
27. Bajramova S.T., Agapashaeva S.M., Aliev O.M. Sintez, vyrashchivanie monokristallov i lyumi-nescentnye svojstva EuCuBiS3. Materialy XXI Rossijskoj mezhdunarodn. konf. «Problemy te-oreticheskoj i eksperimental'noj himii. Ekaterinburg: 2011. S. 316-317
28. Bajramova S.T., Alieva R.A., Aliev O.M. Fazovye ravnovesiya v sisteme Cu2S-EuS-Sb2S3. Azerb. him.zhurnal. 2010. № 2. S. 65-70.
29. Alieva R.A., Bajramova S.T., Ragimova V.M., Aliev O.M. Diagrammy sostoyaniya sistem CuSbS2-MeS (Me=Pb, Eu, Yb). Neorgan. materialy. 2010. T. 46. №7. S. 7836-787.
30. Bajramova S.T., Bagieva M.R, Agapashaeva S.M., Aliev O.M. Sintez i svojstva strukturnyh analogov minerala burnonita. Neorgan. materialy. 2011. T.47. № 4. S. 1-4.
31. Aliev O.M., Azhdarova D.S., Agaeva R.M., Maksudova T.F., Ragimova V.M. Fazoobra-zovaniya v kvazibinarnoj sisteme Cu2S-PbS-Sb2S3. Mezhdun. Zhurn. Prikl. i Fundam. issledovanii, 2016. Ch.8. № 12. S. 1482-1488.
32. Aliev O.M., Ajdarova D.S., Maksudova T.F., Ragimova V.M. Phase equilibrium in systems Cu2S-PbCuSbS3 and CuSbS2-Pb5Sb4S11. Reports NASA Chem. Sciens. 2018. No 1. P.49-52.
33. Aliev O.M., Ajdarova D.S., Bayramova S.T., Ragimova V.M. Nonstoichiometriya in PbCuSbS3 compound. Azerb. Chem. journal. 2016. No 2. P. 51-54.
34. Aliev O.M., Azhdarova D.S., Agaeva R.M., Maksudova T.F. Fazoobrazovanie v razrezah Cu2S (Sb2S3, PbSb2S4, PbsSb4Sn)-PbCuSbS3 v kvazitrojnoj sisteme Cu2S-PbS-Sb2S3 i fizicheskie svojstva tverdyh rastvorov (Sb2S3)i-x(PbCuSbS3)x. ZHurn. Neorgan. Materialy. 2018. T. 54. № 12. S.1275-1280
35. Alieva R.A., Bajramova S.T., Aliev O.M. Sintez i dogo tela i funkcional'nye materialy". Rossiya,
svojstva soedinenij so strukturoj, proizvodnoj ot Ekaterinburg: 2008. S. 11-12.
struktury burnonita. Materialy konf. "Himiya tver-
PbLnCuS3 (Ln-La, Nd, Sm, Gd, Dy, Er) TIPLI BIRLO§MOLORIN SINTEZI, MONOKRISTALLARIN
YETͧDÍRÍLMOSÍ VO XASSOLORÍ
Ó.M.Oliyev, D.S.Ojdarova, T.F.Maksudova, V.M.Rahimova, S.T.Bayramova
PbLnCuS3 (Ln-La, Nd, Sm, Gd, Dy, Er) tipli dordlü sulfoduzlar ya element komponentlarinin aridilmasindan, ya da havasi qovulmu§ va qaynaq olunmu§ kvars ampulaya yerla§dirilmi§ qrafit potada 1200-1275 К temperaturda 2PbS+Cu2S+Ln2S3 ¡jixtasindan alinmi§dir. PbSmCuS3 va PbGdCuS3 birla§malarinin monokristali mineralla§ma metodu ila yetiíjdirilmiíjdir Rentgenqurulu;? analizinin naticalarina gora PbLnCuS3 tipli birla§malar ortorombik sinqoniyada kristalla§ir ((а=8.26^8.20; b=8.84^8.80; с= 7.96^ 7.9 A, f.q. Pmn2i) PbGdCuS3 sirasi maddalarinda qurulu§ tipinin mübadilasina asaslanan (PbCuSbS3 ^KZrCuSe3 ^ Eu2CuS3) morfotropiya hadisasi mü§ahida olunur. Onlarin standart termodinamiki funksiyalari hesablanmi§ va maqnit hassasliginin temperatur asililiqlari 6lgülmü§dür.
Agar sozlzr: sulfoduz, faza diaqrami, kristal qurulu§, qsfas parametri, termodinamiki funksiya, maqnit hdssasligi.
СИНТЕЗ, ВЫРАЩИВАНИЕ МОНОКРИСТАЛЛОВ И СВОЙСТВА СОЕДИНЕНИЙ ТИПА PbLnCuS3
(Ln-La, Nd, Sm, Gd, Dy, Er)
О.М.Алиев, Д.С.Аждарова, Т.Ф.Максудова, В.М.Рагимова, С.Т.Байрамова
Четверные сульфиды типа PbLnCuS3 (Ln-La, Nd, Sm, Gd, Dy, Er) получали либо сплавлением элементов, либо через шихты, 2PbS+Cu2S+Ln2S3 в графитовом тигле, находящимся в запаянной кварцевой ампуле при температуре 1200-1275 К. Монокристаллы PbSmCuS3 и PbGdCuS3 выращивали методом минерализации. Рентгенографическое исследование показало, что соединения типа PbLnCuS3 кристаллизуются в орторомбической сингонии (а=8.26^8.20; b=8.84^8.80; с= 7.96^- 7.9 A, пр. группа Pmn21). В ряду соединений PbLnCuS3 проявляется явление морфотропии, заключающееся в обмене структурного типа (PbCuSbS3 ^KZr-CuSe3 ^ Eu2CuS2), т.е. при изменении радиуса катиона Ln. Вычислены их стандартные термодинамические функции и измерены температурные зависимости магнитной восприимчивости.
Ключевые слова: сульфосоль, фазовые диаграммы, кристаллическая структура, параметр решетки, термодинамические функции, магнитная восприимчивость
