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AZERBAIJAN CHEMICAL JOURNAL № 1 2019
UDC.541.19.23+657.19.23
CHARACTER OF INTERACTION AND GLASS FORMATION IN THE
AsSe-NdAs2Se4 SYSTEM
T.MJlyasly1, A.G.Khudiyeva1, I.I.Aliyev2, M.G.Shakhbazov3
!Baku State University [email protected]
л
M.Nagiyev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
3Azerbaijan State Pedagogical University Received 29.03.2018
The character of the chemical interaction and glass formation in the AsSe-NdAs2Se4 system was studied by physico-chemical analysis methods (DTA, RFA, MSA), as well as by measuring the microhardness and density, and a state diagram of this system was plotted. It is established that the AsSe-NdAs2Se4 system is partially quasi-binary section of the As-Nd-Se ternary system. Solid solutions on the basis of the starting components have not been practically established. In the system with slow cooling, the glass formation region on the basis of AsSe reaches 15 mol% NdAs2Se4, and 20 mol% NdAs2Se4 in the quenching regime on ice water.
Keywords: microhardness, system, phase diagram, eutectic, density. https://doi.org/10.32737/0005-2531-2019-1-50-53
Semiconductor materials on the basis of arsenic chalcogenides as photosensitive materials are transparent in the IR spectrum and are widely used in the electronics industry [1-5]. Chalcogenides of neodymium and their alloys refer to promising substances for the development of magnetic and thermoelectric materials [6]. Therefore, the study of the interaction between the chalcogenides AsSe and NdAs2Se4 is of scientific and practical importance. The last years with participation of arsenic chalcogeni-des there are studied ternary and quaternary systems [7-11].
In the present paper, we offer the synthesis conditions and the results of investigating the certain physico-chemical properties of the AsSe-NdAs2Se4 system alloys.
AsSe is a glassy semiconductor, melts at 3150C [12], and crystallizes in a monoclinic symmetry with unit cell parameters: a = 6.69, b = 13.86, c = 11.00 A, p = 11302'(Ave P21/n) [13], microhardness #=1060 MPa and density p = 5.30 g/sm .
Compound NdAs2Se4 melts incongruent-ly at 6750C and crystallizes in tetragonal system with lattice parameters: a = 12.62, c = 7.42 A,
3 3
Z = 7, ppicn = 5.75 g/sm , px-ray = 5.99 g/sm .
AЗЕРБАЙДЖАНСКИЙ ХИМИЧЕСКИЙ ЖУРНАЛ № 1 2019
Experimental part
The alloys of the system were synthesized from AsSe and NdAs2Se4 components in quartz ampoules evacuated to 0.1333 Pa at 500-9000C.
To achieve an equilibrium state, the alloys were annealed at 2000C for 350 hours.
The alloys of the system were investigated by differential thermal (DTA), X-ray diffraction (XRD) and microstructural (MSA) analyses, as well as by measuring microhardness and density.
Differential thermal analysis was carried out in the thermograph "Termoskan-2". The Al2O3 compound was used as a reference, and the heating rate was 100C/min.
X-ray phase analysis was performed on a D2 PHASER X-ray diffractometer. For the study CuXa-radiation and Ni filter were used.
MSA alloys of pre-etched polishing, polished with GOI paste was performed on a metallographic microscope MIM-8, KOH: C2H5OH=2:1, etching time 20 s was used at studying the microstructure of the alloys. The microhardness of the alloys of the AsSe-NdAs2Se4 system was measured on a PMT-3 device at loads of 0.10 and 0.15 N.
CHARACTER OF INTERACTION AND GLASS FORMATION
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The density of the alloys was determined by a pycnometric method, toluene was used as the working fluid.
Results and discussion
AsSe riched alloys are obtained in a glassy state. The obtained ingots are dense, in the concentration range 0-25 mol% NdAs2Se4 -dark black color. The alloys of the AsSe-NdAs2Se4 system are resistant to air, water and organic solvents. Concentrated mineral acids (H2SO4, HNO3) and alkali (NaOH, KOH) decompose them.
All alloys in the AsSe-NdAs2Se4 system were investigated before and after annealing. To plot the phase diagram of the AsSe-NdAs2Se4 system, the data of the physico-chemical analysis of the samples after annealing were used.
DTA alloys of the AsSe-NdAs2Se4 system before annealing showed that on the ther-mograms of the samples in the concentration range of 0-25 mol% NdAs2Se4 there are softening temperatures (7g), varing within 170-1800C (Table 1). An annealing was carried out at 1900C for 540 h to crystallize the vitreous alloys.
Table 1. Composition, DTA results, microhardness, and density determination (glassy form) for glass alloys of the AsSe-NdAs2Se4 system_
Mole % Thermal events during heating, 0C Density, g/cm3 Microhardness, MPa
AsSe NdAs2Se4 AsSe NdAs2Se4
P=0.10 N P=0.20 N
100 0.0 170, 315 5.30 1060 -
95 5.0 170, 240, 270, 300 5.32 1100 -
90 90 175, 240, 270, 280 5.46 1120 -
85 15 175, 240, 305 5.54 1150 -
80 20 180, 240, 360 5.60 1150 1825
75 25 180, 240, 275, 400 5.65 - 1830
70 30 240, 310, 470 5.70 - 1840
Table 2. Composition, DTA results, microhardness, and density determination (crystalline) for glass alloys of the AsSe-NdAs2Se4 system_
Mole % Thermal events during heating, 0C Density g/cm3 Microhardness, MPa
AsSe NdAs2Se4 AsSe NdAs2Se4
P=0.10 N P=0.20 N
100 0.0 315 5.48 780 -
95 5.0 240, 270, 300 5.52 790 -
90 90 240, 270, 280 5.56 870 -
85 15 240, 305 5.59 880 -
80 20 240, 360 5.64 880 1825
75 25 240, 275, 400 5.69 - 1830
70 30 240, 310, 470 5.75 - 1840
DTA alloys after annealing showed that the heating curves of the annealed samples showed no softening point (Table 2). This proves that all the glassy alloys after annealing are completely crystallized.
MSA alloys of the AsSe-NdAs2Se4 system were carried out before and after annealing. The study of the microstructure of alloys showed that all of them in the solid state are biphasic.
Two series of values of microhardness of the alloys of the system was obtained (Tables 1, 2). For vitreous alloys, the value of the microhardness varies within the range H^ = 10601150 MPa. After annealing, the microhardness values for the same alloy region were 780-880 MPa.
X-ray analysis of the alloys of the AsSe-NdAs2Se4 system was carried out to confirm the results of DTA and MSA. Before annealing the alloys in the range concentration of 0-25 mol% NdAs2Se4 the intense diffraction maxima was not observed (Figure 1, a). After annealing, diffraction patterns of the same alloys show intense diffraction peaks (Figure 1, b).
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T.M.ILYASLY et al.
t,oC 1200
1000 800
600 400 300 200 100
1200o
675o
AsSe 20 40 60 80 NdAs2Se4
Fi g. 2 . Phases diagram of the system AsSe-NdAs2Se4.
On the basis of the physico-chemical analysis, a phase diagram of the AsSe-NdAs2Se4 system is constructed (Figure 2). As can be seen from Figure 2, the AsSe-NdAs2Se4 system is a partially nonquasi-binary section of ternary As-Nd-Se system bat is stable in subsoliduse.
Liquidus of the system consists of curves
of primary crystallization of AsSe and NdAs2Se4. Above the solidus temperature (2400C) in the concentration range of 0-20 mol% NdAs2Se4 there are three-phase regions of L+AsSe+NdSe, and in the range of 20-100 mol% -L+NdSe+NdAs2Se4. Below the solidus line, the two-phase alloys AsSe+NdAs2Se4 crystallize.
A3EPEAH#^AHCKHH XHMHHECKHH ^YPHAH № 1 2019
CHARACTER OF INTERACTION AND GLASS FORMATION
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AsSe-NdAs2Se4 SÍSTEMÍNDO QAR§ILIQLI TOSÍR VO SÜ^aaMOLaGOLMa
T.M.ilyasli, A.Q.Xudiyeva, LLOliyev, M.H.§ahbazov
Fiziki-kimyavi analiz metodlan (DTA, RFA, MQA, elaca da sixligin va mikrobarkliyin ôlçûlmasi) vasitasila AsSe-NdAs2Se4 sisteminda kimyavi qarçiliqli tasirin xarakteri tadqiq edilmiç va onun faza diaqrami qurulmuçdur. Müayyan edilmiçdir ki, AsSe-NdAs2Se4 kasiyi As-Sb-Se sisteminin qisman kvazibinar kasiyidir. Sistemda ilkin komponentlar asasinda bark mahlul sahasi praktiki olaraq açkar edilmamiçdir. Sistemda yavaç soyudulma zamani AsSe asasinda 15 mol% NdAs2Se4 çûça sahasi amala galir, buzlu suda birbaça soyudulma zamani isa çûça sahasi 20 mol% NdAs2Se4 taçkil edir.
Açar sozter: mikrobarklik, sistem, faza diaqrami, evtektika, sixliq.
ХАРАКТЕР ВЗАИМОДЕЙСТВИЯ И СТЕКЛООБРАЗОВАНИЯ В СИСТЕМЕ AsSe-NdAs2Se4
Т.М.Ильяслы, А.Г.Худиева, И.И.Алиев, М.Г.Шахбазов
Методами физико-химического анализа (ДТА, РФА, МСА), а также измерением микротвердости и плотности изучен характер химического взаимодействия и стеклообразования в системе AsSe-NdAs2Se4 и построена диаграмма состояния. Установлено, что система AsSe-NdAs2Se4 является неквазибинарным сечением тройной системы As-Nd-Se. Твердые растворы на основе исходных компонентов практически не установлены. В системе при медленном охлаждении область стеклообразования на основе AsSe доходит до 15 мол.% NdAs2Se4, а в режиме закалки в ледяной водe - до 20 мол.% NdAs2Se4.
Ключевые слова: микротвердость, система, фазовая диаграмма, эвтектика, плотность.
