Continuous Series Of Solid Solutions Research Articles

Experimental investigation of the solid phase equilibria at 300 K in the SnBi2Te4-PbBi2Te4-Bi2Te3 system

The phase equilibria of the SnBi2Te4-PbBi2Te4-Bi2Te3 system were experimentally studied using differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. According to the experimental results, the isothermal section of the system at 300 K were constructed and 4 single-phase and 3 two-phase regions were identified. It was shown that along with previously confirmed SnBi2Te4–PbBi2Te4 and SnBi4Te7–PbBi4Te7 sections, SnBi6Te10–PbBi6Te10 section forms continuous series of solid solutions with a tetradymite-type layered structure. Lattice parameters of solid solutions were determined by full-profile Rietveld refinements and results show that both a and c parameters increase linearly with the Pb concentration according to Vegard's law. This study can help elucidate the phase equilibria of the SnTe-PbTe-Bi2Te3 pseudo-ternary system which provides important information for the design of new tetradymite-type layered phases with topological insulator and thermoelectric properties.

Isothermal section of the ZrO2–HfO2–Nd2O3 ternary phase diagram at 1100 °C

In the presented work, based on the results obtained by X-ray diffraction and microstructural analysis, phase equilibria have been studied and an isothermal section of the ZrO2–HfO2–Nd2O3 ternary phase diagram at 1100 °C has been constructed. Unit cell parameters were calculated by the least squares method using the LATTIC software. The International Powder Standards Committee database (JSPSDS International Center for Diffraction Data 1999) was used to determine the phase composition.It was found that in the studied system are formed regions of solid solutions based on a cubic fluorite-type (F) modification, a tetragonal (T) modification of ZrO2, a monoclinic (М) modification of HfO2, a hexagonal (А) modification of Nd2O3, as well as an ordered (Py) pyrochlore phase of Nd2Zr2O7 (Nd2Hf2O7). The boundaries of the phase regions and the unit cell parameters are determined. A continuous series of solid solutions based on the ordered pyrochlore (Py) phase of Nd2Zr2O7 (Nd2Hf2O7) at the studied temperature is derived. The unit cell parameters of the ordered pyrochlore (Py) phase vary from a = 1.0633 nm for the two-phase composition (Py + M), 47.5 mol% ZrO2 – 47.5 mol% HfO2 – 5 mol% Nd2O3) to a = 1.0639 nm for the boundary composition of the solid solution (37.5 mol% ZrO2 – 37.5 mol% HfO2 – 30 mol% Nd2O3) and then up to a = 1.0648 nm for the two-phase (Py + A) composition (30 mol% ZrO2 – 30 mol% HfO2 – 40 mol% Nd2O3) which located along the Nd2O3 – (45 mol% ZrO2 – 55 mol% HfO2) constant ratio line. The studied isothermal section is characterized by the formation of two three-phase (Py + F + M and F + T + M) and six two-phase (A + Py, Py + M, Py + F, F + M, T + M, F + T) regions. In the ZrO2–HfO2–Nd2O3 ternary system, no new phases are detected at the temperatures studied.

Phase equilibria in the Ag8SiSe6-Ag8SiTe6 system and characterization of the solid solutions Ag8SiSe6-xTex

Due to polymorphism and complex crystal structure, compounds of the argyrodite family and phases based on them exhibit several interesting functional properties, such as thermoelectric, photoelectric, optical, as well as ionic conductivity for Cu+ and Ag+ cations. The paper presents the results of the study of phase equilibria in the Ag8SiSe6-Ag8SiTe6 system by DTA, XRD, and SEM methods. Refined data on the melting temperature (1278 K) and polymorphic transitions (315 K and 354 K) of the Ag8SiSe6 compound are presented. The crystallographic parameters of LT-Ag8SiSe6 (Cubic, F-43m, a = 1.0965 nm) and IT-Ag8SiSe6 (Cubic, P4232, a = 1.0891 nm) are also determined. It has been established that the investigated system is quasi-binary and its phase diagram is characterized by the formation of a continuous series of substitutional solid solutions between HT-Ag8SiSe6 and Ag8SiTe6. This process is accompanied by a strong decrease in the temperatures of polymorphic transformations of Ag8SiSe6, which leads to the stabilization of the ion-conducting cubic phase at room temperature in the >10 mol% Ag8SiTe6 compositions area. The crystal lattice parameters of the synthesized solid solutions are calculated by indexing the powder diffraction patterns. The stabilization of the high-temperature cubic phase at room temperature achieved by us presents new opportunities for the development of environmentally friendly thermoelectrics and ion-electronic conductors based on silicon argyrodites with desired composition and properties.

Phase equilibria in the ZrO2–HfO2–Nd2O3 system at 1500 °C and 1700 °C

The phase equilibria in the ZrO2–HfO2–Nd2O3 ternary system at 1500 °C and 1700 °C were studied over the whole concentration range by X-ray diffraction and microstructural analyses. Corresponding isothermal sections were constructed from the data obtained. It was found that solid solutions in this system are derived from a tetragonal (T) modification of ZrO2, a monoclinic (M) modification of HfO2, a hexagonal (A) modification of Nd2O3, a cubic phase with a fluorite (F) structure of ZrO2 (HfO2), and an ordered phase with a pyrochlore (Py) structure of Nd2Zr2O7 (Nd2Hf2O7). The phase boundaries and unit cell lattice parameters were determined. The solubility of Nd2O3 in M − HfO2 is pretty low and about less than 1 mol%, as confirmed by XRD and microstructural analyses. The ordered pyrochlore-type (Py) phase of Nd2Zr2O7 (Nd2Hf2O7) forms continuous series of solid solutions at 1500 °C and 1700 °C. The homogeneous region of these continuous series of solid solutions changes insignificantly with increasing temperature. The changes in the construction of the isothermal section of the ZrO2-HfO2-Nd2O3 phase diagram at 1500 °C compared to 1700 °C are associated with the thermal stability of cubic fluorite-type (F) solid solutions. Other phases in the ZrO2-HfO2-Nd2O3 ternary system are not detected at the studied temperatures.

First-principles demonstration of band filling-induced significant improvement in thermodynamic stability and mechanical properties of Sc_{1-x}Ta_{x}B_{2} solid solutions

Mixtures of different metal diborides in the form of solid solutions are promising materials for hard-coating applications. Herein, we study the mixing thermodynamics and the mechanical properties of AlB_{2}-structured Sc_{1-x}Ta_{x}B_{2} solid solutions using the first-principles method, based on the density functional theory, and the cluster-expansion formalism. Our thermodynamic investigation reveals that the two diborides readily mix with one another to form a continuous series of stable solid solutions in the pseudo-binary TaB_{2}-ScB_{2} system even at absolute zero. Interestingly, the elastic moduli as well as the hardness of the solid solutions show significant positive deviations from the linear Vegard’s rule evaluated between those of ScB_{2} and TaB_{2}. In case of Sc_{1-x}Ta_{x}B_{2}, the degrees of deviation from such linear trends can be as large as 25, 20, and 40% for the shear modulus, the Young’s modulus, and the hardness, respectively. The improvement in the stability as well as the mechanical properties of Sc_{1-x}Ta_{x}B_{2} solid solutions relative to their constituent compounds is found to be related to the effect of electronic band filling, induced upon mixing TaB_{2} with ScB_{2}. These findings not only demonstrate the prominent role of band filling in enhancing the stability and the mechanical properties of Sc_{1-x}Ta_{x}B_{2}, but also it can potentially open up a possibility for designing stable/metastable metal diboride-based solid solutions with superior and widely tunable mechanical properties for hard-coating applications.

PHASE RELATIONS IN THE Ag8SiS6–Ag8SiTe6 SYSTEM AND CHARACTERIZATION OF SOLID SOLUTIONS

Argyrodite family compounds and phases based on them are valuable ecologically friendly functional materials that exhibit a number of functional propreties, such as thermoelectric, photoelectric, optical, and other. On the other hand, having Cu+ and Ag+ ion conductivity, they are ionic conductors, and can be used as electrochemical sensors, electrodes, or electrolyte materials in solid-state batteries, displays, etc. In the present paper, phase relations in the Ag8SiS6–Ag8SiTe6 system were studied by differential thermal analysis and X-ray diffraction phase techniques and a T-x phase diagram was constructed. It is established that the system is quasi-binary and is characterized by the formation of a continuous series of substitutional solid solutions between Ag8SiTe6 and HT- Ag8SiS6 compounds. With the formation of solid solutions, the temperature of the polymorphic transition of the Ag8SiS6 decreases. This leads to the stabilization of the ion-conducting cubic phase in the range of compositions 30 mol. % Ag8SiTe6 at room temperature and below. The homogeneity regions based on RT-Ag8SiS6 are 10 mol. %. According to XRD data, the crystal lattice parameters of the obtained solid solutions were calculated and a their linear dependence on the composition is shown

Recrystallization effect on mechanical parameters and increasing of Ag+ ionic conductivity in Ag7(Si1-xGex)S5I ceramic materials

This paper presents the preparation and investigation of Ag7(Si1-xGex)S5I (х = 0.2; 0.4; 0.6; 0.8) ceramic materials. Powder patterns of Ag7(Si1-xGex)S5I indicate the formation of a continuous series of solid solutions with the F-43m cubic cell. Ag7(Si1-xGex)S5I ceramic discs with a porosity of 10 ± 1% were obtained by cold pressing followed by annealing at 700°С. Fabricated ceramics were studied by the SEM, EDS, EIS methods and microhardness measurement. The obtained ceramics are characterized by chemical homogeneity and close values of the average crystallite size in the range of 2.52–2.70 μm. Frequency and temperature dependences of electrical conductivity were analyzed by Nyquist plots. The compositional behavior of ionic conductivity is non-linear and is characterized by a conductivity maximum (8.10 × 10−2 S/cm) at x = 0.6. The temperature dependence of the ionic component obeys to Arrhenius law. The influence of the recrystallization process on the electrical parameters of Ag7(Si1-xGex)S5I solid solution microceramics is discussed.

Effects of niobium doping on perovskite La0.5Sr0.5Fe1−xNbxO3−δ structure

Perovskites based on lanthanum-strontium ferrite are considered promising electrode materials for use in various types of fuel cells. The strategy of modifying these materials by partial substitution of iron with highly charged ferroactive cations has proven to be an effective way to enhance their chemical stability. It was shown here that La0.5Sr0.5Fe1−xNbxO3−δ forms a continuous series of substitutional solid solutions up to niobium concentration x = 0.1. It was found for the first time that a further increase in the niobium concentration leads to a transformation of initial rhombohedral (hexagonal) perovskite structure (R3‾c) to less symmetrical structure of orthorhombic perovskite (Pbnm). The latter also forms a number of substitutional solid solutions in the range 0.1 < x ≤ 0.25. High-temperature diffraction analyses of perovskites of composition La0.5Sr0.5Fe1−xNbxO3−δ (x = 0.03, 0.05, 0.1) were carried out in the air atmosphere and in vacuum. It was demonstrated that with an increase in the Nb content in the perovskite, the temperature of the “hexagonal-cubic” phase transition goes up, which indicates an increase in the structural stability of the oxide in the range of operating temperatures of SOFCs/SOECs.

НОВЫЕ ДАННЫЕ ОБ ОСОБЕННОСТЯХ ЛОКАЛЬНОЙ СТРУКТУРЫ ТВЕРДОГО РАСТВОРА Ca9La(PO4)7(1-x)(VO4)7x:Eu3+(1 %)

Solid solutions of phosphate-vanadates Ca9La(PO4)7(1–x)(VO4)7x:Eu3+(1 %) with the structure -Ca3(PO4)2 activated by europium were synthesized by the standard solid-phase method. It is shown that a continuous series of solid solutions is formed upon substitution P5+ → V5+. At the same time, the study by the second harmonic generation method showed that a symmetry inhomogeneity is observed in the series. When studying the luminescent properties, standard transitions of the europium cation with the dominant electric dipole transition 5D0 → 7F2 were found. The most intense emission was demonstrated by compositions with a centrosymmetric structure.

Silver and Gold Containing Compounds of p-Block Elements As Perspective Materials for UV Plasmonics.

We present a review of phase formation tendencies, methods for preparation and optical properties of alloys and compounds from the binary systems of silver or gold with metals and metalloids from the p-block of the Periodic system of elements. Reference data about the homogeneity regions in the systems of interest, together with information about the crystalline structure of existing indexed compounds in them, is proposed and statistically analyzed. General background for the synthesis of intermetallic alloys and compounds, and the tendencies for their preparation for plasmonic purposes are presented. The high plasma frequency, ωp of p-block metals makes their alloys with silver and gold an interesting object of study, due to the possibility of ωp variation over a wide interval in the ultraviolet (UV) spectral region with a view to finding more efficient materials for excitation of a localized surface plasmon resonance (LSPR) necessary for various applications and techniques operating in this part of the electromagnetic spectrum. Unlike the alloys between the noble metals Cu, Ag, and Au, which form continuous series of solid solutions, different areas can be observed in the phase diagrams of the Ag(Au)-p-block systems, containing solid solutions, intermetallic compounds, and heterogeneous mixtures. The ability to vary the plasma frequency of solid solutions, like the alloys between the noble metals Cu, Ag, and Au, is the reason to pay attention to the compositions of the Ag(Au-p-block systems that fall in these regions of their phase diagrams. The analysis of the published results for complex permittivity shows that the addition of small amounts of conductive p-block elements to noble metals reduces the energy gap for interband transitions and increases their plasmonic activity in the UV spectral range. The article analyzes the relationship between electrical resistivity and LSPR excitation efficiency, which shows that the intermetallic compounds from Ag(Au)-p-block systems with a well-ordered crystalline structure and good conductivity level can be more effective materials for UV plasmonics than the boundary solid solutions. Intermetallic compounds can be easily obtained in the form of bulk samples, thin films, and nanoparticles with controlled size and geometric shape. The spectral dependences of the plasmon efficiency of the intermetallic compounds, determined from their complex permittivity functions, show that they are promising materials for excitation of LSPR in the UV spectral region.

Ag8GeS6(Se6)–Ag8GeTe6 SYSTEMS: PHASE RELATIONS, SYNTHESIS, AND CHARACTERIZATION OF SOLID SOLUTIONS

Phase equilibria in the Ag8GeS6-Ag8GeTe6 and Ag8GeSe6-Ag8GeTe6 systems were studied using differential thermal analysis and powder X-ray diffraction technique. The T-x phase diagrams were constructed. It has been found that both systems are partially quasi-binary and are characterized by the formation of continuous series of substitutional solid solutions between Ag8GeTe6 and high-temperature cubic modifications of Ag8GeS6 and Ag8GeSe6. When solid solutions are formed, the temperatures of polymorphic phase transitions of these compounds decrease. This leads to the stabilization of the ion-conducting cubic phase in the 40 mol% Ag8GeTe6 range of compositions at room temperature and below. The regions of homogeneity based on Ag8GeS6 and Ag8GeSe6 are 15 and 10 mol.%, respectively. The crystal lattice parameters of the identified solid solutions were calculated from the XRD data, and their linear dependence on the composition is shown

PHASE EQUILIBRA IN THE Ag2Se–Ag8GeSe6–Ag8SiSe6 SYSTEM AND CHARACTERIZATION Of the Ag8Si1-xGexSe6 SOLID SOLUTIONS

Phase equilibria in the Ag2Se–Ag8SiSe6–Ag8GeSe6 system were studied by differential thermal analysis and X-ray diffraction thechnique. Based on the experimental results and literature data, the projection of the liquidus surface of the Ag2Se–Ag8SiSe6–Ag8GeSe6 system, the isothermal section at 300 K and some polythermal sections of the phase diagram were constructed. It was determined that continuous series of solid solution are formed based on high-temperature cubic modification and limited solid solution areas are formed based on low-temperature modification of initial compounds on the Ag8SiSe6–Ag8GeSe6 side of concentration triangle. The formation of solid solutions leads to a sharp decreasing of polymorphic transition temperatures of ternary compounds and stabilization of high-temperature phases at room temperature. The liquidus surface of the Ag2Se–Ag8SiSe6–Ag8GeSe6 system consists of 2 areas reflecting the initial crystallization of α'-phase based on HT-Ag2Se and HT-Ag8Si1-xGexSe6 solid solutions. The obtained new phases are of interest as environmentally safe materials with thermoelectric properties and mixed ion-electron conductivity.

PHASE RELATIONS IN THE Sb2Te2S-Bi2Te2S SYSTEM AND CHARACTERIZATION OF Sb2-xBixTe2S SOLID SOLUTIONS

The phase equilibria of the Sb2Te2S-Bi2Te2S system was studied by powder X-ray diffraction (PXRD), differential thermal analysis (DTA), scanning electron microscope (SEM) and energy dispersive Xray (EDX) microanalysis. It was shown that due to incongruent melting of the Sb2Te2S compound the system is non-quasibinary, but it is stable below the solidus and characterized by the formation of a continuous series of solid solutions with a tetradymite-like hexagonal structure. The lattice parameters were determined from powder diffraction patterns. It was established that the crystal lattice parameters of solid solutions vary linearly with composition

Dynamics of cluster structure change in melts that forms a continuous series of solid solutions during equilibrium and nonequilibrium crystallization

В работе описана динамика изменения структуры расплава при охлаждении твердых растворов замещения в процессе квазиравновесной (КРК) и неравновесно-взрывной кристаллизаций (НРВК) с учетом процессов кластеризации. Определены границы перехода в твердое состояние по мере изменения кластерной структуры при кристаллизациях типа КРК и НРВК. Границы определены с учетом критического перегрева и предкристаллизационного переохлаждения относительно линии ликвидус . Определено, что при квазиравновесной кристаллизации расплав меняет свою структуру в следующей последовательности , а при неравновесно-взрывной кристаллизации – в последовательности Применено правило фаз для расчета первых кристаллов, появившихся при различных видах кристаллизаций. Представлены кривые охлаждения сплавов, описывающие различные виды кристаллизации сплавов.

Layered Gadolinium-Europium-Terbium Hydroxides Sensitised with 4-Sulfobenzoate as All Solid-State Luminescent Thermometers

Ternary layered gadolinium-europium-terbium basic chlorides were synthesised using a facile hydrothermal-microwave technique. A continuous series of solid solutions was obtained in a full range of rare earth concentrations. To sensitise the luminescence of Eu3+ and Tb3+, a 4-sulfobenzoate anion was intercalated in the ternary layered rare earth hydroxides using one of two methods—a high-temperature ion exchange or a single-stage synthesis. The luminescent colour of the materials was governed by the gadolinium content: at low and medium gadolinium concentrations (0–70%), layered Gd-Eu-Tb basic sulfobenzoate exhibited a bright red europium luminescence; at high gadolinium content (70–90%), a bright green terbium luminescence was observed. The colour coordinates of layered Gd-Eu-Tb basic sulfobenzoate luminescence depended on the temperature in the physiological range (20–50 °C). The relative thermal sensitivity of the obtained materials was up to 2.9%·K−1.

Zaykovite, Rh3Se4, a new mineral from the Kazan placer, South Urals, Russia

AbstractZaykovite, ideally Rh3Se4, is a new mineral, the first natural rhodium selenide. It was discovered in the assemblages of platinum-group minerals from the Kazan gold placer, South Urals, Russia. The mineral occurs as crystals up to 40 μm in size within the grains of Pt3Fe alloy, in association with unnamed Pd–Sb–Te phase and Au–Pd alloy. In reflected light, zaykovite has a grey colour with bluish-greenish tint; it shows weak bireflectance and anisotropy. Reflectance values [Rmax/Rmin (%) for COM approved wavelengths (nm)] are: 30.1/29.3(470), 32.2/31.0(546), 33.4/32.0(589) and 35.1/33.7(650). The chemical composition corresponds to the empirical formula (Rh2.26Pt0.46Ir0.25Ru0.01Pd0.01Fe0.01)Σ3.00(Se2.77S1.21Te0.02)Σ4.00 Zaykovite is monoclinic, space group C2/m, a = 10.877(1), b = 11.192(1), c = 6.4796(6) Å, β = 108.887(2)°, V = 746.3(1) Å3, Z = 6 and Dcalc = 8.32 g cm–1. The crystal structure has been solved and refined to R1 = 0.016 based on 858 unique observed reflections. The strongest lines of the powder X-ray diffraction pattern [d(Å), (I), (hkl)] are: 5.43(37)($\bar{1}$11), 3.275(75)(310), 3.199(100)($\bar{1}$31), 3.061(87)(002), 2.568(62)(400), 2.545(41)(041), 3.413(34)($\bar{2}$41) and 1.697(34)(441). Zaykovite is a Se analogue of kingstonite, Rh3S4. A continuous series of solid solutions between kingstonite and zaykovite was encountered in the samples from the Kazan placer. The possible sources of this unique Rh–Se mineralisation in the South Urals could be serpentinised dunite–harzburgite or gabbro–clinopyroxenite–dunite complexes in the vicinity.

Phase equilibria in the ZrO2–HfO2–Sm2O3 system at 1500 °С

The phase equilibria in the ternary system ZrO 2 –HfO 2 –Sm 2 O 3 were studied by X-ray diffraction and microstructural analyses. The formation of new phases in the ZrО 2 –HfO 2 –Sm 2 O 3 system at 1500 °С was not observed. It is established that in the studied system at 1500°C the fields of solid solutions based on tetragonal (T) modification of ZrО 2 , monoclinic (M) modifications of HfO 2 , and monoclinic (B) modifications of Sm 2 O 3 , and ordered phase with the structure of pyrochlore-type (Py) Ln 2 Zr 2 O 7 (Ln 2 Hf 2 O 7 ) are present. The boundaries of the phase fields and the parameters of the unit cells of the formed phases are determined. The studied isothermal cross section of the ZrО 2 –HfO 2 –Sm 2 O 3 system is characterized by the formation of continuous series of cubic solid solutions based on a phase with a structure of the pyrochlore-type Sm 2 Zr 2 O 7 (Sm 2 Hf 2 O 7 ) and a structure of the fluorite type F-ZrO 2 (HfO 2 ). It is established that two regions of homogeneity of cubic solid solutions are formed in the determined system. The existence of these regions of homogeneity is due to the rupture of the solubility of the F-ZrO 2 (HfO 2 ) phase in the region of the existence of an ordered phase with a pyrochlore-type structure Sm 2 Zr 2 O 7 (Sm 2 Hf 2 O 7 ). It is established that the solid solution based on a cubic modification with fluorite-type structure exists in equilibrium with all phases observed in the system. Isothermal section of the phase diagram of the system ZrO 2 –HfO 2 –Sm 2 O 3 at 1500°C has been characterized by the presence of one three-phase (F + T + M), as well as five two-phase (B + F, two - F + Py, M + F, T + F) regions.

Effect of Fe-Doping on Thermal Expansion and Stability of Bismuth Magnesium Tantalate Pyrochlorere.

A continuous series of solid solutions (Bi1.5Mg0.75-xFexTa1.5O7±Δ (x = 0-0.75)) with the pyrochlore structure were synthesized with the solid-phase method. It was shown that iron, like magnesium, is concentrated in the structure in the octahedral position of tantalum. Doping with iron atoms led to an increase in the upper limit of the thermal stability interval of magnesium-containing pyrochlore from 1050 °C (x = 0) up to a temperature of 1140 °C (x = 1). The unit cell constant a and thermal expansion coefficient (TEC) increase uniformly slightly from 10.5018 Å up to 10.5761 Å and from 3.6 up to 9.3 × 10-6 °C-1 in the temperature range 30-1100 °C. The effect of iron(III) ions on the thermal stability and thermal expansion of solid solutions was revealed. It has been established that the thermal stability of iron-containing solid solutions correlates with the unit cell parameter, and the lower the parameter, the more stable the compound. The TEC value, on the contrary, is inversely proportional to the cell constant.

High ionic conductivity of K5-xTlx(Mg0.5Hf1.5)(MoO4)6 (0 ≤ х ≤ 5) solid solutions

Novel K5-xTlx(Mg0.5Hf1.5)(MoO4)6 (0 ≤ х ≤ 5) oxides were successfully synthesized by solid state reaction. The results indicate the formation of a continuous series of solid solutions with the NASICON-like structure (sp. gr. R3‾c) in the composition range 0 < x < 5. The unit-cell parameters of the solid solutions increase linearly with composition, as a consequence of thallium substitution for potassium. The cation conductivity of Tl5Mg0.5Hf1.5(MoO4)6 has been shown to exceed the conductivity of the parent potassium magnesium hafnium molybdate. The highest total conductivity of 2.49 × 10−3 S/cm was found at 831 K for Tl5Mg0.5Hf1.5(MoO4)6.

PHASE RELATIONS AND CHARACTERIZATION OF SOLID SOLUTIONS IN THE SnBi2Te4–PbBi2Te4 AND SnBi4Te7–PbBi4Te7 SYSTEMS

Phase equilibria in SnBi2Te4¬–PbBi2Te4 and SnBi4Te7–PbBi4Te7 systems were studied using differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. It has been shown that both systems are characterized by the formation of a continuous series of solid solutions with a tetradymite-like layered structure. The lattice parameters of solid solutions are linear functions of composition