scholarly journals Растворимость теллура в кристаллах TlGaTe-=SUB=-2-=/SUB=-, TlInTe-=SUB=-2-=/SUB=- и электрофизические свойства твердых растворов

2018 ◽  
Vol 60 (9) ◽  
pp. 1656
Author(s):  
А.И. Наджафов ◽  
Н.А. Алиева ◽  
К.Г. Халилова

AbstractThe complex methods of the physicochemical analysis are used to study TlGaTe_2–Te and TlInTe_2–Te alloys in which the tellurium solubility region up to 5.0 at % is observed. The temperature dependences of the lattice parameters and the electrical conductivity of TlGaTe_2 + x and TlInTe_2 + x have been studied in different crystallographic directions. The TlGaTe_2 + x and TlInTe_2 + x solid solutions undergo a phase transition at a temperature of 498 K. The transition nature is interpreted.

Author(s):  
Ч.И. Абилов ◽  
М.Ш. Гасанова ◽  
Н.Т. Гусейнова ◽  
Э.К. Касумова

The results of studying the temperature dependences of electrical conductivity, thermoelectric coefficient, Hall mobility of charge carriers, total and electronic thermal conductivity, as well as phonon thermal resistance of alloys of (CuInSe2)1-x(In2Te3)x solid solutions at x=0.005 and 0.0075 are presented. The values ​​of these parameters for certain temperatures were used to calculate the values ​​of the thermoelectric figure of merit of the indicated compositions. It turned out that as the temperature rises, the thermoelectric figure of merit tends to grow strongly, from which it can be concluded that these materials can be used in the manufacture of thermoelements.


Author(s):  
Н.П. Степанов ◽  
В.Ю. Наливкин ◽  
А.К. Гильфанов ◽  
А.А. Калашников ◽  
Е.Н. Трубицына

Solid solutions Bi2Te3-Sb2Te3 continue to be the subject of numerous and versatile experimental studies due to their practical importance for thermoelectric materials science. In this regard, the problem of studying the regularities of changes in the state of the electronic system of these semiconductors from composition and temperature remains urgent. This paper presents the results of studying the temperature dependences of the magnetic susceptibility of Bi2Te3-Sb2Te3 crystals containing 10, 25, 40, 50, 60 mol. % Sb2Te3. The correlation of the behavior of the temperature dependences of the magnetic susceptibility and electrical conductivity is analyzed.


2020 ◽  
Vol 65 (3) ◽  
pp. 225
Author(s):  
J. I. Huseynov ◽  
Kh. A. Hasanov ◽  
T. A. Jafarov ◽  
I. I. Abbasov

The interactions in the SnSe–TbSe system are investigated, and the solubility region of TbSe in SnSe is determined from the results of a complex physicochemical analysis. The dependence of the electrical conductivity and the concentration of current carriers of TbxSn1−xSe crystals on the composition and temperature is analyzed.


2019 ◽  
Vol 61 (1) ◽  
pp. 200
Author(s):  
А.В. Карташев ◽  
И.Н. Флёров ◽  
М.В. Горев ◽  
Н.В. Михашенок

AbstractCrystalline samples of the (La_1 – _ y Eu_ y )_0.7Pb_0.3MnO_3 ( y = 0, 0.2, 0.4, 0.5, 0.6, and 0.8) manganite solid solutions have been grown. Temperature dependences of the specific heat, thermal expansion, and high-intensity magnetocaloric effect have been investigated. A comparative analysis of the effect of isovalent cationic substitution on the thermal and caloric parameters of the ferromagnetic phase transition has been made. It has been shown that the growth of the Eu atom concentration leads to a decrease in the phase transition entropy and an increase in the baric coefficient dT / dp . Field and temperature dependences of the magnetocaloric effect have been established. It is demonstrated that, varying the ratio of cations, one can obtain the solid solutions with the maximum magnetocaloric effect value in fields of up to 6 kOe in a temperature range of 90–340 K. Owing to the similar reduced relative cooling powers, the investigated solid solutions can be used as reference solid-state cooling media in designing the cascade cooling systems.


Author(s):  
Екатерина Владимировна Барабанова ◽  
Никита Михайлович Оспельников ◽  
Александра Ивановна Иванова

Введение легирующих примесей является классическим способом модификации свойств сложных оксидов семейства перовскита с общей формулой ABO. В качестве основы для создания твердых растворов широко используется ниобат натрия NaNbO. Введение замещающих катионов проводится как по позиции A, так и по позиции B. При этом особый интерес представляет случай, когда валентность легирующей примеси больше или меньше валентности исходного катиона в узле. В этом случае образуется дефектная структура, которая может обладать уникальными свойствами. Данная работа посвящена исследованию электрофизических свойств керамики ниобата натрия с примесью Fe. Замещение производилось по позициям катионов ниобия Nb . Показано, что для таких составов характерно значительное увеличение электропроводности, понижение температуры Кюри и размытие фазового перехода. Introduction of dopants is a classic method for modifying properties of perovskite complex oxides of the family of general formula ABO. Sodium niobate NaNbO is widely used as a basis for creating solid solutions. The introduction of substitutional cations is carried out at both position A and at position B . Of particular interest is the case when valence of the dopant is greater or less than valence of the initial cation at the site. In this case, a defected structure is formed, which may have unique properties. This work is devoted to study of the electrical properties of sodium niobate ceramics doped with Fe . The substitution was carried out according to positions of the nibium cations Nb . It is shown that such compositions are characterized by a significant increase in electrical conductivity, a decrease in the Curie temperature, and a diffuse of the phase transition.


2020 ◽  
Vol 86 (3) ◽  
pp. 35-47 ◽  
Author(s):  
Oksana Kornienko ◽  
Oleksandr Bykov ◽  
Аnatoliy Sameliuk ◽  
Yuri Yurchenko

Using the methods of physicochemical analysis (XRD, petrography, scanning electron microscopy analyses) phase equilibria were firstly investigated in the ternary system СeO2–La2O3–Eu2O3 system at 1250 ºС. It was established that in the system there exist fields of solid solutions based on cubic with fluorite-type structure (F) and cubic (С) and monoclinic (B) modification Eu2O3 and hexagonal (A) modification of La2O3. No new phases were found. The refined lattice parameters of the unit cells for solid solutions for the systems were determined. The cubic ceria-based solid solution has a fluorite-type structure and homogeneity field shows the maximum extension. It forms solid solutions of substitution type with phases of binary systems. The boundary of the homogeneity field of F-phase is curved from the center of triangle toward the CeO2 corner and passes through appropriate points in the binary CeО2-Eu2O3(100-69 mol % CeO2) and CeO2–La2O3 (100-51 mol% CeO2) systems. The lattice parameters for F phase vary from  а = 0.5409 nm in pure СеО2toа = 0.5512 nm in two-phase sample (F + C) containing 55 mol % CeО2-22.5 mol % La2O3-22.5 mol % Eu2O3and to а = 0.5526 nm in  three-phase sample (F + В  + C) containing 40 mol % CeО2-30 mol % La2O3-30 mol % Eu2O3 and to а = 0.5532 nm in  three-phase sample (А + F + В) containing 30 mol % CeО2-35 mol % La2O3-35 mol % Eu2O3along the section CeO2 ( 50 mol % La2O3-35 mol % Eu2O3). The lattice parameters for F phase vary from  а = 0.5409 nm in pure СеО2 to а = 0.5444 nm nm in two-phase sample (F + C), containing 70 mol % CeО2-3 mol % La2O3-27 mol % Eu2O3and to а = 0.5465 nm in  three-phase sample (F + В  + C) containing 20 mol % CeО2-8 mol % La2O3-72 mol % Eu2O3. The homogeneity field of solid solution based on A-La2O3 extends to 17 mol % СеO2 and 20 mol % Eu2O3 in the corresponding binary systems and locates near the composition 5 mol % CeO2-90 mol % La2O3-5 mol % Eu2O3 on the section La2О3 - (50 mol % CeО2-50 mol % Eu2О3). The boundary of the homogeneity field of B- Eu2O3 phase passes through appropriate points in the binary CeО2-EuO3 (0-1 mol% CeO2) and–Eu2O3 (0-25 mol% La2O3) systems. The isothermal section of the CeO2– La2O3–Eu2O3 system at 1250°C contains four three-phase regions (A+F+B, F+B+C) and five two-phase regions (F+A, A+B, F+B, B+C, F+C).


2019 ◽  
Vol 12 (04) ◽  
pp. 1950048
Author(s):  
A. V. Solnyshkin ◽  
I. L. Kislova ◽  
I. M. Morsakov ◽  
A. A. Golishnikov ◽  
A. N. Belov ◽  
...  

The film structures on the base of soft and crystalline ferroelectrics (poly(vinylidene fluoride - trifluoroethylene) copolymer and deuterated triglycine sulfate) were produced. The volume content of the DTGS microcrystal particles embedded in the polymer matrix of the composite films was up to 10%. It was found crystalline phase changes in the polymer matrix at the DTGS inclusions presence. The DTGS crystal particles increased dielectric permittivity and electrical conductivity of the composite films. The temperature dependences of the dielectric permittivity indicated increasing the phase transition temperature of polymer matrix at the DTGS inclusions growth.


2020 ◽  
Vol 62 (4) ◽  
pp. 537
Author(s):  
А.В. Сотников ◽  
В.В. Баковец ◽  
Michihiro Ohta ◽  
А.Ш. Агажанов ◽  
С.В. Станкус

The temperature dependences of Seebeck coefficient, electrical conductivity (Т=300–873K), thermal conductivity and figure of merit (Т=300–770K) of polycrystalline samples of solid solutions based on gadolinium and dysprosium sulfides with γ-GdxDy1-xS1.49 (x=0.1, 0.2, 0.3, 0.4) composition were studied. It was established that samples morphological features, namely, the specific surface area of crystallites causing a change in the number of deformation centers determines the thermal conductivity of -GdxDy1-xS1.49, and it was found that there is an anomalous decrease in thermal conductivity for composition with х = 0.2. For this composition the lowest values of Seebeck coefficient -371 mkV/K at 873K, electrical resistivity 880 mkΩ∙m at 873K and thermal conductivity 0.68 ± 0.03 W/m·K at 770K were obtained, in this case the thermoelectric figure of merit reaches ZT = 0.23.


Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 746
Author(s):  
Meiling Hong ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Xinyu Zhang

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.


2008 ◽  
Vol 179 (27-32) ◽  
pp. 1432-1435 ◽  
Author(s):  
Elena Konysheva ◽  
John T.S. Irvine ◽  
Astrid Besmehn

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