scholarly journals Features of the Solid Solution (Mo0.9,Cr0.1)Si2 Formation Depending on the State of Initial Mixture

2013 ◽  
Vol 2 (6) ◽  
pp. 202-209 ◽  
Author(s):  
I. Kud ◽  
L. Ieremenko ◽  
L. Likhoded ◽  
I. Uvarova ◽  
D. Zyatkevich
Keyword(s):  
Solid Solution ◽  
Initial Mixture ◽  
The State

An Investigation on Vacuum Brazing of Dissimilar Nonferrous Metals of Cu and Al

2013 ◽  
Vol 690-693 ◽  
pp. 2565-2569
Author(s):  
Wei Yuan Yu ◽  
Tian Dong Xia ◽  
Wan Wu Ding ◽  
Xiao Jun Wang ◽  
Wen Jun Zhao
Keyword(s):  
Solid Solution ◽  
Nonferrous Metals ◽  
The State ◽  
Metal Compounds ◽  
Average Width ◽  
Cu Substrate ◽  
Vacuum Brazing ◽  
Transition Area ◽  
Microstructure Morphology

The writer successfully obtained brazed Cu-Al joint by using vacuum brazing method, and also conducted an analysis for the microstructure morphology of the joint. The result shows that: The interface of the brazed Cu-Al joint includes three parts---the transition area on the Cu side, the central brazing seam area and the transition area on the Al side. Formed between the brazing seam area and the Cu substrate are the Cu3Al2 and CuAl2 layers, and the average width of the transition area of Cu3Al2 is 12 μm while that of CuAl2 8 μm. The brazing seam area is mainly composed of α-Al solid solution, Cu3Al2 and CuAl2 metal compounds, in addition, the ε-Cu15Si4 phase, the Al-Si phase and CuZn2 phase are also formed. These phases present themselves in the state of acicular compounds, which are dispersed in the brazing seam area.

Engineering of Synthesis of Eu,Ca-α-Sialon Phosphor via the Solid-Liquid Synthesis

2017 ◽  
Vol 904 ◽  
pp. 125-129
Author(s):  
Malgorzata Sopicka-Lizer ◽  
Tomasz Pawlik ◽  
Daniel Michalik ◽  
Radosław Lisiecki
Keyword(s):  
Solid Solution ◽  
Optical Properties ◽  
Phase Composition ◽  
Quantum Yield ◽  
Graphite Furnace ◽  
Initial Mixture ◽  
Synthesis Temperature ◽  
Alumina Addition ◽  
A Minor ◽  
Solid Liquid

The aim of this research was to find out the way of the synthesis temperature reduction without deterioration of the phosphors optical properties. Since crystallization of Eu,Ca-α-sialon occurs by means of sialon crystallization from the oversaturated oxynitride liquid, thus a rise of the liquid phase amount could be performed not only via an increase of temperature but also through the application of the low eutectic additives. Al2O3 and AlF3 additives have been chosen as the sources of liquid at the reaction temperature. The syntheses were carried out in a graphite furnace at 1650°C and the powders were characterized for their phase composition, particles morphology, excitation and emission properties and their quantum yield of luminescence was compared. It has been found that alumina addition to the initial mixture of nitrides was the most effective in formation of sialon solid solution with a minor contamination with AlN. Emission intensity of sialon phosphor was doubled if they were synthesized with each of additives. Quantum yield of tested phosphors was over 0.85 if excited at 380 nm for alumina and similar for AlF3 modified composition. A significant particles refinement was observed if AlF3 was applied.

scholarly journals “Invisible” gold in synthetic and natural arsenopyrite crystals (Vorontsovka deposit, Northern Urals)

2019 ◽  
Vol 61 (5) ◽  
pp. 62-83
Author(s):  
E. V. Kovalchuk ◽  
B. R. Tagirov ◽  
I. V. Vikentyev ◽  
D. A. Chareev ◽  
E. E. Tyukova ◽  
...  
Keyword(s):  
Solid Solution ◽  
Negative Correlation ◽  
Local Level ◽  
Ore Deposits ◽  
The State ◽  
Salt Flux ◽  
Strong Negative Correlation ◽  
Positive Correlation ◽  
Sulfur Fugacity ◽  
The Difference

In many types of hydrothermal ore deposits Au occurs in invisible state in most common minerals of the Fe-As-S system. It is supposed that the state of theinvisible Au may beeither non-structural (nano-sized inclusions of metal and its compounds) or chemically bound (isomorphous solid solution). Here we report results of investigation of the state and the concentration range ofinvisible Au in synthetic and natural arsenopyrites FeAsS (Vorontsovka deposit, North Urals, type Carlin). Conditions that favor the formation of Au-bearing arsenopyrite were identified. The synthesis experiments were carried out in Au-saturated system by means of salt flux method with a stationary temperature gradient. The temperature at the cold end of the ampole was 400500С. The chemical composition of arsenopyrite was determined by electron probe microanalysis. The composition of the synthesized arsenopyrite varied within [at.%]: Fe from 32.6 to34.4, As from 30.0 to 36.5, S from 29.4 to36.0. The Au content in arsenopyrite varied from the detection limit ( 45ppm) to 3wt.%. A strong negative correlation between the concentrations of Au and Fe was observed in the synthesized arsenopyrite grains. The slope of the correlation lines corresponds to the formation of the Au-bearing solid solution where Au isomorphically substitutes for Fe at the parameters of the synthesis experiments. In addition, there is a weaker positive correlation between Au and As: higher Au concentrations are characteristic of arsenic-rich compositions (As/S [at.%] 1) and those close to stoichiometric arsenopyrite, whereas in sulfur-rich arsenopyrite the concentration of Au is lower and does not exceed 0.25wt.%. The positive Au-As correlation appears not only on a local level within a single crystal of synthetic and natural arsenopyrite, but is valid on the Vorontsovka deposit scale: As-rich arsenopyrite formed at lower temperature and sulfur fugacity (t= 250370C, logfS2= 1217) contains more Au than the As-poor early arsenopyrite (t= 270400C, logfS2= 79). Comparison of these results with the literature data shows that the positive correlation between the concentrations of Au and As in arsenopyrite and the negative correlation between the concentrations of Au and Fe are the common features of ores of the Carlin-type deposits. We suggest that, in contrast to negative correlation Au-Fe, the positive correlation Au-As cannot be explained in terms of crystal chemistry, but can result from the effect of external factors among which are the difference in composition of ore-forming hydrothermal fluids and the sulfur fugacity.

The State of Platinum in Pyrite Studied by X-Ray Absorption Spectroscopy of Synthetic Crystals

2019 ◽  
Vol 114 (8) ◽  
pp. 1649-1663 ◽  
Author(s):  
Olga N. Filimonova ◽  
Maximilian S. Nickolsky ◽  
Alexander L. Trigub ◽  
Dmitriy A. Chareev ◽  
Kristina O. Kvashnina ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Absorption Spectroscopy ◽  
The State ◽  
Salt Flux ◽  
Chemical Modeling ◽  
Processing Technologies ◽  
X Ray ◽  
The Matrix ◽  
X Ray Absorption

Abstract Pyrite (FeS2) is a typical container of Pt in ores of magmatic and hydrothermal origin and in some carbonrich ores of sedimentary-diagenetic origin. Knowledge of the state of Pt disseminated in the matrix of pyrite, including local atomic environment (type of atoms in the nearest and distant coordination shells, coordination numbers, interatomic distances) and oxidation state, is necessary for physical-chemical modeling of platinum group element mineralization and for the improvement of Pt ore extraction and processing technologies. Here we report results of an investigation of local atomic structure of synthetic Pt-bearing pyrites by means of X-ray absorption spectroscopy (XAS). Synthesis experiments, performed at 580° and 590°C in a Pt-saturated system by means of salt-flux method, yielded crystals of pyrite with concentrations of Pt up to 4 wt %. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) showed that the distribution of Pt within the pyrite grains is of zonal character, but within the distinct zones Pt is distributed homogeneously. Negative correlation between the concentrations of Pt and Fe was observed in the synthesized pyrite grains. The slope of the correlation line corresponds to the formation of the solid solution in the Pt-Fe-S system and/or to the formation of PtS2. The XAS experiments revealed the existence of two forms of Pt in pyrite. The main form is the solid solution Pt(IV), which isomorphically substitutes for Fe. The Pt-S distance in pyrite is ~0.1 Å longer than that of Fe-S in pure pyrite. The distortion of the pyrite crystal structure disappears at R >2.5 Å. The second Pt-rich form was identified by means of high-resolution transmission electron microscopy (HRTEM) as nanosized inclusions of PtS2. Heating experiments with in situ registration of X-ray absorption spectra resulted in partial decomposition (dissolution) of PtS2 nanosized inclusions with the formation of the solid solution (Fe1–xPtx)S2. Therefore, the PtS2 nanosized particles can be considered as a quench product. Our data demonstrate that both Pt solid solution and PtS2 nanosized inclusions (at high Pt content) can exist in natural Pt-bearing pyrites.

Spinodal Decomposition in Fe(1-X)O-Fe3o4 Sintered Ceramics.

2000 ◽  
Vol 6 (S2) ◽  
pp. 366-367
Author(s):  
A. Huerta ◽  
H. A. Calderon ◽  
M. Umemoto ◽  
M. E. Brito
Keyword(s):  
Solid Solution ◽  
Milling Time ◽  
Initial Mixture ◽  
Ceramic Materials ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Initial Content ◽  
Diffraction Patterns

Ceramic materials in the system FeO-Fe3o4 have been produced by means of mechanical milling and sintering for application of their physical properties. Starting from powder mixtures of Fe and Fe3o4 or Fe and Fe2o4, as well as pure Fe3o4, a metastable solid solution of Fe and O has been produced. The amount of Fe dissolved varies according to the milling time and its initial content in the mixture. A protective Ar atmosphere is used in all stages of the milling process in order to avoid contamination. X-ray diffraction patterns show a clear displacement of the intensity maxima as a function of the milling time, suggesting the formation of a solid solution from the initial mixture. Use of Mossbauer spectroscopy reveals an increasingly higher amount of metastable wustite (Fe(1-X) as a function of milling time i.e., 500 h and 1000 h of milling produce 67 and 74 mol % Fe(1-X)O, respectively.

Influence of laser radiation on the state of a solid solution of iron in silicon

1975 ◽  
Vol 5 (2) ◽  
pp. 240-241 ◽  
Author(s):  
A A Zolotukhin ◽  
L I Ivanov ◽  
L S Milevskii ◽  
E G Prutskov ◽  
V A Yanushkevich
Keyword(s):  
Solid Solution ◽  
Laser Radiation ◽  
The State

scholarly journals Изменение термодинамических свойств твердого раствора Si-Ge при уменьшении размера нанокристалла

2019 ◽  
Vol 61 (11) ◽  
pp. 2169
Author(s):  
М.Н. Магомедов
Keyword(s):  
Solid Solution ◽  
Thermodynamic Properties ◽  
Binary Alloy ◽  
Specific Volume ◽  
Pressure Range ◽  
Basic Research ◽  
State Equation ◽  
The State ◽  
Basic Research Project ◽  
Academy Of Sciences

In the framework of the “medium atom” model for a binary alloy, the state equation and the thermodynamic properties of the Si0.5-Ge0.5 solid solution are calculated. Using the RP model of the nanocrystal, the changes of both the state equation and thermodynamic properties are calculated during the transition from a macrocrystal to a nanocrystal of 222 atoms with a geometric Gibbs surface. The calculations were carried out along the isotherms T = 100, 300 and 1000 K, in the pressure range: – 1 < P < 7 GPa. The change in the properties of both at the isochoric and at isobaric (P = 0) decrease in the number of atoms in a nanocrystal were studied. It is shown that at an isobaric (P = 0) decrease of size, the specific volume of the Si0.5-Ge0.5 nanocrystal increases the more, the higher the nanocrystal temperature. This work was supported by the Russian Foundation for Basic Research (project no. 18-29-11013_mk) and the program no. 6 of the Presidium of the Russian Academy of Sciences (grant no. 2-13)

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