Solid Solution Crystals Research Articles

Modeling of nonlinear processes of nucleation and growth of GaSxSe1–x(0 ≤ х≤ 1) solid solutions

The results on the study of modeling and physico-chemical study of the kinetics ofnucleation and growth of GaSxSe1–x(0 ≤ х≤ 1) solid solution. The nucleation heterogeneous process and growth of GaSxSe1–xcrystals have been studied and simulated taking into account nonlinear equations considering the kinetic behavior of crystallizing phases.GaSxSe1–xsingle and nanocrystals were grown from solution, melt, and by chemical transport reaction through steam. GaSxSe1–xcrystals were grownbychemical transport reaction in a two-tem-perature gradient furnace in a sealed quartz ampoule. Iodine was used as a transporting additive. Using the Fokker–Planck equation, the evolution of the distribution function of crystals of solid solutions of the GaS–GaSe system by size at the nucleation time is studied by a numerical method. For the convenience of comparing theory with experimental data, we used the GaS1–xSex(x= 0.7 molar fraction of GaSe) composition of the solid solution. The Monte Carlo method is used to approximate the time evolution of the nucleation of two types of particles for the GaS0.3Se0.7 solid solution, simulated by a constant nucleus size. The results of modeling non-linear crystallization processes are consistent with experimental data.

Formation of Macrotubular Crystals of Salicylic Acid through Ripening of Solid Solution Crystals Containing Impurity Gradients

Formation of Macrotubular Crystals of Salicylic Acid through Ripening of Solid Solution Crystals Containing Impurity Gradients

La1–yBayF3–y Solid Solution Crystals as an Effective Solid Electrolyte: Growth and Properties

A series of nonstoichiometric La1–yBayF3–y (0 ≤ y ≤ 0.12) single crystals with a tysonite-type structure (sp. gr. P-3c1) was grown from the melt by the directional crystallization method in a fluorinating atmosphere, and some physical properties were characterized. The concentration dependence of electrical conductivity σdc(y) La1–yBayF3–y crystals was studied. The composition of the ionic conductivity maximum for this solid electrolyte was refined. It was confirmed that the maximum conductivity σmax = 8.5 × 10–5 S/cm (295 K) was observed at the composition ymax = 0.05 ± 0.01. Analysis of the electrophysical data for the group of tysonite-type solid electrolytes R1–yMyF3–y (M = Ca, Sr, Ba, Eu2+ and R = La, Ce, Pr, Nd) showed that the compositions of the maxima of their conductivity were close and amount to y = 0.03−0.05. This fact indicates a weak influence of the size effect (ionic radii R3+ and M2+) on the value of ymax for R1–yMyF3–y solid electrolytes.

A threshold heating rate for single‐stage heat treatments in glass‐ceramics containing seed formers

AbstractThe development of glass‐ceramic materials is often achieved using an elementary microstructural strategy that splits the tasks of seed formation and functionality between two types of crystals. This strategy requires customized time‐temperature ceramization protocols, which have been so far implemented using empirical parameters. Here, a more fundamental approach is proposed: the extent of overlap Oe between seed formation and volume crystallization is evaluated by calorimetric and dilatometric measurements, targeting the computation of a threshold heating rate qt for effective single‐stage heat treatments. The applicability of this novel parameter is tested in TiO2‐doped lithium magnesium aluminosilicate glass‐ceramics, whose seed formation stage is thoroughly characterized by Raman spectroscopy and STEM. High‐temperature X‐ray diffraction demonstrates that insufficient seeding results in potentially weaker performances of the final products, due to large sizes and silica deficiency of the functional quartz solid solution crystals.

Study of (In2S3)х·(AgIn5S8)1–х solid solutions

Herein, single crystals of compounds In2S3, AgIn5S8 and solid solutions (In2S3)x·(AgIn5S8)1–x were grown by directional crystallization. The composition of the obtained single crystals was determined by microprobe X-ray spectral analysis. It is found that the content of the components in the grown single crystals is in satisfactory agreement with the specified composition in the initial charge. The structure of the obtained materials was determined by the X-ray method. It is shown that both the initial compounds and the solid solutions based on them were crystallized in the cubic structure of the spinel. The unit cell parameters of the In2S3, AgIn5S8 compounds and the solid solutions based on them, which vary linearly with the composition x, were calculated by the least squares method. The density was determined by the pycnometric method, and the microhardness of the In2S3 and AgIn5S8 compounds and the (In2S3)x·(AgIn5S8)1–x solid solutions was determined by the Knoop method. It is shown that the density, like the unit cell parameter, changes linearly with the composition x, but the dependence of microhardness on the x parameter has a maximum for x = 0.4. Using differential thermal analysis (DTA), the temperatures of phase transformations were determined and the phase diagram of the In2S3–AgIn5S8 system was constructed, which is characterized by a small crystallization interval and belongs to type III according to the Rosebom classification. The curves of liquidus and solidus are concave to the abscissa axis and have a common point.

A Semiempirical Model for Barium-Strontium-Sulfate Solid Solution Scale Crystallization and Inhibition Kinetics at Oilfield Conditions

Summary Scale inhibitors have been widely used as one of the most efficient methods for sulfate-scale control. To accurately predict the required minimum inhibitor concentration (MIC), we have previously developed several crystallization and inhibition models for pure sulfate scales, including barite, celestite, and gypsum. However, disregarding the wide existence of barium-strontium-sulfate (Ba-Sr-SO4) solid solution in the oil field, no related models have been developed that would lead to large errors in MIC determination. In this study, the induction time of Ba-Sr-SO4 solid solution was measured by laser apparatus with or without different concentrations of scale inhibitor diethylenetriamine penta(methylene phosphonic acid) (DTPMP) at the conditions of barite saturation index (SI) from 1.5 to 1.8, temperature (T) from 40 to 70°C, and [Sr2+]/[Ba2+] ratios from 0 to 15 with celestite SI < 0. The results showed that the Ba-Sr-SO4 solid solution’s induction time increases with the [Sr2+]/[Ba2+] ratio at a fixed barite SI, T, and DTPMP dosage. That means the MIC will be overestimated if it is calculated by the previous semiempirical pure barite crystallization and inhibition models without considering the presence of Sr2+. To resolve such deviations, the novel quantitative Ba-Sr-SO4 solid solution crystallization and inhibition models were developed for the first time. The novel models are in good agreement with the experimental data. They can be used to predict the induction time and MIC more accurately at these common Ba2+ and Sr2+ coexisting scenarios. The observations and new models proposed in this study will significantly improve the barite scale management while Ba2+ and Sr2+ coexist in the oil field.

The effects of a Li2O excess on the crystallization sequence of lithium aluminosilicate glass powders

The surface crystallization of melt-quenched lithium aluminosilicate (LAS) glasses with SiO2-contents between 77 and 79 mol% was investigated by high-temperature X-ray diffractometry. Glasses possessing a ratio Li/Al > 1 underwent far earlier crystallization (starting from 750°C) than their stoichiometric counterparts, developing solely quartz solid solution (Qss) and keatite solid solution (Kss) crystals during a heat treatment up to 1200°C. In turn, samples with Li/Al = 1 devitrified only above 900°C and exhibited the transient formation of cristobalite, whose lattice constants hint at a slight Li+Al stuffing. The composition, structural parameters and critical inversion temperature Tc of the obtained Qss crystals were analyzed and compared with the available literature sources, reaffirming the established mutually linear dependence between these properties.

Transparent glass-ceramics based on Co2+-doped γ-GaxAl2−xO3 spinel nanocrystals for passive Q-switching of Er lasers

Transparent glass-ceramics (GCs) based on Co2+-doped γ-GaxAl2−xO3 spinel nanocrystals were developed in the lithium aluminogallosilicate glass system with TiO2 as a nucleating agent. The initial glass contains spinel nanocrystals with sizes less than 3 nm. Secondary heat-treatments in the temperature range of 680–800 °C result in fabrication of transparent GCs based on γ-GaxAl2−xO3 crystals enriched in aluminum with cubic spinel structure (sp. gr. Fd3m) and a mean size up to 5.5 nm. At higher temperatures, GCs become translucent and then opaque due to additional crystallization of lithium aluminosilicate solid solutions (ss) with β-quartz structure and lithium aluminogallium silicate ss with β-spodumene (keatite) structure. The introduction of gallium oxide improves the temperature stability of spinel crystals that are not decomposed at high heat-treatment temperatures when aluminosilicate crystals evolve. The Co2+ ions in GCs enter the spinel crystals predominantly in tetrahedral sites. Transparent GCs feature broadband absorption (1.15–1.7 μm) owing to the 4A2(4F) → 4T1(4F) transition of IVCo2+ species in spinel nanocrystals. They exhibit saturable absorption and high ground-state absorption (GSA) cross-section σGSA of 3.1 ± 0.4 × 10−19 cm2 at 1.54 μm. Glass-ceramic based on γ-GaxAl2−xO3 crystals is employed as a saturable absorber of an eye-safe diode-side-pumped Er3+,Yb3+:glass laser delivering 1.1 mJ/42 ns pulses at 1535 nm.

Three-Component Zone-Melting Method: Modeling of the Concentration-Component Distribution in Single Crystals of Ge–Si Solid Solutions

The concept and theoretical basis of the three-component zone melting method is given for growing single crystals of semiconductor solid solutions using seeds from constituent components. In the Pfann approximation, the problem of the axial concentration distribution of components in Ge–Si single crystals grown at different values of the operating parameters such as the length of the melted zone and the composition of the initial macrohomogeneous rods of solid solutions is solved. Analysis of the obtained results determines the potentialities of the method and the optimal conditions for growing single crystals with given homogeneous and graded compositions in the entire continuous series of Ge–Si solid solutions. It is shown that the three-component zone-melting method is promising for the growth of single crystals of semiconductor solid solutions.

Dielectric properties of solid solutions in a PFN-based system

The results of X-ray diffraction analysis of the solid solutions in the (1-x)Pb(Fe1/2Nb1/2)O3–xPb(Fe2/3W1/3)O3 systems with x = 0.0÷0.5, investigating their microstructure and measurements of dielectric characteristics are presented in this paper. The critical influence of Pb(Fe2/3Wy1/3)O3 on the crystallization of solid solutions and the nature of grain boundaries is established. A sintering mechanism of the solid solutions is defined. Correlations between the dynamics of the crystalline and grain structures and the dielectric properties of investigating solid solutions are established.

Фазовый состав, структура и транспортные характеристики кристаллов твердых растворов ZrO-=SUB=-2-=/SUB=--Sc-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- дополнительно легированных Yb-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

The effect of the co-doped Yb2O3 on the transport characteristics and stabilization of the cubic phase in solid solutions based on ZrO2−Sc2O3 has been carried out.(ZrO2)1-x-y(Sc2O3)x(Yb2O3)y solid solution crystals, where (x = 0.07-0.09; y = 0.01-0.03), were grown by directional crystallization of the melt in a cold crucible. It is shown that crystals with a cubic fluorite structure were obtained at a total concentration of stabilizing oxides Sc2O3 and Yb2O3 above 10 mol%. Crystals with a total concentration of stabilizing oxides of 10 mol%, having a pseudocubic t'' -phase structure, at a fixed concentration of Sc2O3, have the maximum conductivity. It is shown that an increase in the Yb2O3 concentration in the field of cubic solid solutions leads to a decrease in the conductivity of the crystal. Crystals (ZrO2)0.9(Sc2O3)0.09(Yb2O3)0.01 have the maximum conductivity in the entire temperature range.

Effect of Ti, Al, Si on the Structure and Mechanical Properties of Boron-Rich Fe–B–C Alloys

The effects of substitution of Fe in the boron-rich Fe–B–C alloys, containing 10.0–14.0 % B; 0.1–1.2 % C; Fe – the remainder, 5.0 % Ti, Al, or Si (in wt. %) have been studied with optical microscopy, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy. Mechanical properties, such as microhardness and fracture toughness, have been measured by Vickers indenter. The microstructure of the master Fe–B–C alloys cooled at 10 and 103 K/s consists of primary dendrites of Fe(B,C) solid solution and Fe2(B,C) crystals. It has been found that titanium has the lowest solubility in the constituent phases of the Fe–B–C alloys, with preferential solubility observed in the Fe(B,C) dendrites, where Ti occupies Fe positions. This element has been shown to be mainly present in secondary phases identified as TiC precipitates at the Fe2(B,C) boundaries. Titanium slightly enhances microhardness and lowers fracture toughness of the boron-rich Fe–B–C alloys due to substitutional strengthening of Fe(B,C) dendrites and precipitation of the secondary phases. The level of the content of Al or Si in the Fe(B,C) and Fe2(B,C) solid solutions and quantity of the secondary phases observed in the structure suggest that more Al or Si are left in the constituent phases as compared with Ti. These elements mainly enter the crystal lattice of Fe2(B,C) phase replacing iron atoms and form at their boundaries AlB12C and SiC compounds respectively. The additions of Al and Si to the boron-rich Fe–B–C alloys help to modify their fragility: while they slightly decrease microhardness values, addition of these elements improves the fracture toughness of the constituent phases. Increase in a cooling rate from 10 to 103 K/s does not bring about any noticeable changes in the solubility behavior of the investigated alloying elements. The rapid cooling gives rise to microhardness and fracture toughness of the phase constituents which average sizes significantly decrease. The effects of the alloying elements on the structure and mechanical properties of the investigated boron-rich Fe–B–C alloys have been explained considering differences in the atomic radii and electronic structure of the solute Ti, Al, or Si atoms.

Van der Waals solid solution crystals for highly efficient in-air photon upconversion under subsolar irradiance.

Triplet-sensitized photon upconversion (UC) has been proposed for broad applications. However, the quest for superior solid materials has been challenged by the poor exciton transport often caused by low crystallinity, a small crystal domain, and aggregation of triplet sensitizers. Here, we demonstrate substantial advantages of the van der Waals solid solution concept to yield molecular crystals with extraordinary performance. A 0.001%-order porphyrin sensitizer is dissolved during recrystallization into the molecular crystals of a blue-fluorescent hydrocarbon annihilator, 9-(2-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (ANNP), which contains bulky side groups. This attempt yields millimeter-sized, uniformly colored, transparent solid solution crystals, which resolves the long-standing problem of sensitizer aggregation. After annealing, the crystals exhibit unprecedented UC performance (UC quantum yield reaching 16% out of a maximum of 50% by definition; excitation intensity threshold of 0.175 sun; and high photostability of over 150 000 s) in air, which proves that this concept is highly effective in the quest for superior UC solid materials.

Effect of Heat Treatment on the Thermal Conductivity of Single Crystals of ZrO2-Based Solid Solutions Stabilized with Scandium and Yttrium Oxides

The effect of heat treatment at 1000°C for 400 h on the thermal conductivity of zirconium dioxide crystals stabilized with scandium oxide (ZrO2)1 – x(Sc2O3)x (x = 0.08–0.10) and simultaneously with scandium and yttrium oxides (ZrO2)1 – x – y(Sc2O3)x(Y2O3)y (x = 0.003–0.20, y = 0.02–0.025) has been studied. In the crystals of zirconium dioxide stabilized with scandium oxide, the most noticeable changes in the thermal conductivity are observed in the 9ScSZ crystals, in which the phase composition is changed and a marked content of the rhombohedral phase appears. These changes are less noticeable in the 8ScSZ crystals and they are mainly due to the ordering of oxygen vacancies and the changes in the microstructures of the samples, and there are no changes in the 10ScSZ crystals. The 10ScSZ crystals have the minimum electrical conductivity before and also after annealing, which is determined by the highest content of scandium oxide in the solid solution. Insignificant changes in the thermal conductivity are observed in crystals of partially stabilized zirconium dioxide co-alloyed with scandium and yttrium oxides. The cubic 8Sc2YSZ and 10Sc2YSZ crystals demonstrate only slight changes in the thermal conductivity, the character of the temperature dependence of the thermal conductivity, and the phase compositions. The alloying of the zirconia–based solid solutions with yttrium oxide simultaneously with scandium oxide enables one to increase the stability of their phase compositions and structurally dependent thermal and electrical physical characteristics.

Large thermoelectric power factor in whisker crystals of solid solutions of the one-dimensional tellurides Ta4SiTe4 and Nb4SiTe4

One-dimensional tellurides Ta4SiTe4 and Nb4SiTe4 were found to show high thermoelectric performance below room temperature. This study reported the synthesis and thermoelectric properties of Ta4SiTe4-Nb4SiTe4 solid solutions and Mo- or Ti-doped (Ta0.5Nb0.5)4SiTe4. Thermoelectric power of the solid solutions systematically increased with increasing Ta content, while their electrical resistivity was unexpectedly small. Mo- and Ti-doped (Ta0.5Nb0.5)4SiTe4 showed n- and p-type thermoelectric properties with large power factors exceeding 40 μW cm−1 K−2, respectively. The fact that not only Ta4SiTe4 and Nb4SiTe4 but also their solid solutions showed high performance indicated that this system is a promising candidate for thermoelectric applications at low temperatures.

The Study of Phase Equilibria and Superprotonic Crystals in the (NH4)2SO4 - K2SO4 - H2SO4 - H2O system

The phase equilibria in the quaternary water-salt system K2SO4 - (NH4)2SO4 - H2SO4 - H2O at a temperature of 35 °C were studied for the first time. The areas of crystallization, solubility, and reproducible conditions for obtaining crystals of solid solutions were determined: (Ki_ x (NH4) x )2SO4, (Ki. x (NH4) x )3H(SO4)2, (Ki. x (NH4) x )9H7(SO4)8H2O, which are superprotonics. The study of phase equilibria in ternary systems K2SO4 - H2SO4 - H2O and (NH4)2SO4 - H2SO4- H2O was carried out, the solubility values and the solubility character of the compounds (NH4)2SO4 and K2SO4, (NH4)3H(SO4)2 and K3H(SO4)2, K9H7(SO4)8H2O, NH4HSO4 n KHSO4 were determined.

Influence of Cerium on the Spectral and Structural Characteristics of LuBo3(Ce,Tb)

Studies of the structure, IR absorption spectra, luminescence spectra, and excitation of luminescence of Ce3+ and Tb3+ ions in crystals of solid solutions of Lu1 – x – yCexTbyBO3 at 0 ≤ x ≤ 0.01 and 0.07 ≤ y ≤ 0.16 have been performed. It has been shown that the solid solution Lu1 – yTbyBO3 synthesized at T = 970°C has the structure of calcite at 0 ≤ y ≤ 0.07, at y ≥ 0.16—the structure of vaterite, and in the range 0.07 < y < 0.16 is two-phase. It has been found that additional doping of 0.5–1 at % Ce3+ of two-phase Lu1 ‒ yTbyBO3 samples, in which the proportion of the vaterite phase does not exceed ∼20%, leads to a significant reduction of the vaterite phase. It has been shown that Ce3+ ions can be used as structurally sensitive and optically active marks in the analysis of the structural state of rare earth element orthoborates.

Microstructural evolution and properties of dual-layer CoCrFeMnTi0.2 high-entropy alloy coating fabricated by laser cladding

The dual-layer CoCrFeMnTi0.2 HEA coating was prepared on 15CrMn steel by laser cladding technology, to investigate the precipitation behavior and the surface properties. The microstructure of the coating is mainly composed of equiaxed crystals of FCC solid solution and intergranular precipitates of Laves phase in the first layer and evolves to the FCC solid solution/Laves lamellar eutectic structure surrounded by martensite and residual FCC solid solution phase in the second layer. The microstructural evolution and the phase transformation are believed to be associated with the dilution effect in the dual-layer deposition and the quenching effect of the multi-track overlapping process. The microhardness of the coating is (428.26 HV0.3) about 3.5 times higher than that of CoCrFeMnNi HEA. It is found that the coating is strengthened by the effect of solid solution strengthening, precipitation strengthening, and martensitic transformation. The values of wear rate show that the wear resistance of the coating is better than that of CoCrFeMnNi HEA. The wear mechanism of the coating is abrasive wear and slight oxidation wear. The coating with the corrosion rate of 0.131 μm/year, exhibits poorer corrosion resistance than CoCrFeMnNi HEA, on account of the formation of corrosion microcells. However, the coating possesses a wider passivation region due to refined grains and high content of passivation elements.

Effect of heat treatment on corrosion and ultrasonic cavitation erosion resistance of AlSi10MnMg alloy

Abstract The investigated alloy is modified by casting with Sr in order to finish the eutectic silicon from microstructure and furthermore subjected to solution treatment followed by natural or artificial aging to improve the usage properties. Metallographic investigations and X-ray diffraction analyses showed that the heat treated microstructure consists of α- solid solution crystals with aluminum base, α + Si eutectic and intermetallic Al-Mn-Si phases. Mechanical tests and ultrasonic cavitation measurements showed that the highest mechanical characteristics and cavitation erosion resistance properties are obtained by applying the solution treatment followed by artificial aging. In contrast, electrochemical tests carried out in a saline concentration of 3.5 % NaCl in order to determine the corrosion rate, indicated that although there are no significant differences between the three structural states, a slight improvement was found in the corrosion behavior after applying the solution treatment followed by both natural and artificial aging. The phenomenon was demonstrated by shifting the values of corrosion currents from 2.66 μm/cm2 for the as-cast state, to 1.81 μm/cm2 and 1.52 μm/cm2, respectively, for the aged states. Finally, analysis of the cavitation eroded surface highlights the presence in the areas with α-solid solution structure of some flat-bottomed striped pinches, characteristic of fatigue fracture and of microcraters in the micro-zones where the fragile intermetallic phases were dislocated.

Enhanced treatment performance of phenol wastewater by electrochemical reactor with MnOx/Ti membrane electrode modified with Sb-SnO2 interlayer People's Republic of China

Sb-SnO2/Ti electrode membrane was prepared by loading Sb-SnO2 polymer precursor on the original Ti substrate electrode membrane, then MnOx sol was coated on the surface of Sb-SnO2/Ti to obtain MnOx/Sb-SnO2/Ti composite electrode membrane via sol–gel method. Compared with MnOx/Ti, the new crystal form and solid solution were identified in MnOx/Sb-SnO2/Ti due to the presence of Sb-SnO2 interlayer, which was beneficial to improve the electrochemical performance of MnOx/Ti. In particular, the specific surface area of MnOx/Ti was increased by inserting Sb-SnO2 interlayer. Electrocatalytic membrane reactor (ECMR) is assembled with the electrode membrane as the anode and the stainless-steel mesh as the cathode for phenolic wastewater treatment. pH value and Sb-SnO2-loading amount had great effect on the energy consumption of ECMR. When the current density, residence time and Sb-SnO2 loading were 0.9 mA/cm2, 15 min and 3.4 wt%, the phenol and COD degradation rate of ECMR with MnOx/Sb-SnO2/Ti reached 98.98% and 89.38%, whereas were 80.56% and 71.12% in case of MnOx/Ti, respectively.