scholarly journals Thermal Analysis and Optimization of the Phase Diagram of the Cu-Ag Sulfide System

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 593
Author(s):  
Fiseha Tesfaye ◽  
Daniel Lindberg ◽  
Dmitry Sukhomlinov ◽  
Pekka Taskinen ◽  
Leena Hupa
Keyword(s):  
Phase Diagram ◽  
Inert Atmosphere ◽  
Thermodynamic Quantities ◽  
Thermal Stabilities ◽  
High Temperature Reaction ◽  
Fusion Data ◽  
Measurement Results ◽  
Pure Substances ◽  
Factsage Software ◽  
First Time

Thermal stabilities of selected ternary phases of industrial interest in the Ag-Cu-S system have been studied by the calorimetric and electromotive force techniques. The ternary compounds Ag1.2Cu0.8S (mineral mackinstryite) and AgCuS (mineral stromeyerite) were equilibrated through high-temperature reaction of the pure Cu2S and Ag2S in an inert atmosphere. The synthesized single solid sample constituting the two ternary phases was ground into fine powders and lightly pressed into pellets before calorimetric measurements. An electrochemical cell incorporating the two equilibrated phase and additional CuS as a cathode material was employed. The measurement results obtained with both techniques were analyzed and thermodynamic properties in the system have been determined and compared with the available literature values. Enthalpy of fusion data of the Ag-richer solid solution (Ag,Cu)2S have also been determined directly from the experimental data for the first time. The thermodynamic quantities determined in this work can be used to calculate thermal energy of processes involving the Ag-Cu-S-ternary phases. By applying the obtained results and the critically evaluated literature data, we have developed a thermodynamic database. The self-developed database was combined with the latest pure substances database of the FactSage software package to model the phase diagram of the Ag2S-Cu2S system.

scholarly journals The Equilibrium Phase Formation and Thermodynamic Properties of Functional Tellurides in the Ag–Fe–Ge–Te System

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1314
Author(s):  
Mykola Moroz ◽  
Fiseha Tesfaye ◽  
Pavlo Demchenko ◽  
Myroslava Prokhorenko ◽  
Nataliya Yarema ◽  
...  
Keyword(s):  
Electromotive Force ◽  
Equilibrium Phase ◽  
Stoichiometric Composition ◽  
Negative Electrode ◽  
Electrochemical Cells ◽  
Thermodynamic Quantities ◽  
Positive Electrodes ◽  
Gibbs Energies ◽  
Buffer Region ◽  
First Time

Equilibrium phase formations below 600 K in the parts Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 of the Fe–Ag–Ge–Te system were established by the electromotive force (EMF) method. The positions of 3- and 4-phase regions relative to the composition of silver were applied to express the potential reactions involving the AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 compounds. The equilibrium synthesis of the set of phases was performed inside positive electrodes (PE) of the electrochemical cells: (−)Graphite ‖LE‖ Fast Ag+ conducting solid-electrolyte ‖R[Ag+]‖PE‖ Graphite(+), where LE is the left (negative) electrode, and R[Ag+] is the buffer region for the diffusion of Ag+ ions into the PE. From the observed results, thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 were experimentally determined for the first time. The reliability of the division of the Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 phase regions was confirmed by the calculated thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 in equilibrium with phases in the adjacent phase regions. Particularly, the calculated Gibbs energies of Ag2FeGeTe4 in two different adjacent 4-phase regions are consistent, which also indicates that it has stoichiometric composition.

First Results from the VULCAN Diffractometer at the SNS

2010 ◽  
Vol 652 ◽  
pp. 105-110 ◽  
Author(s):  
X.L. Wang ◽  
Thomas Holden ◽  
A.D. Stoica ◽  
K. An ◽  
H.D. Skorpenske ◽  
...  
Keyword(s):  
Neutron Beam ◽  
Research Opportunities ◽  
Instrument Performance ◽  
Measurement Results ◽  
First Results ◽  
Design Calculations ◽  
New Research ◽  
First Time

On Friday June 26, 2009, the neutron beam shutter for the VULCAN diffractometer at the SNS was opened for the first time. Initial measurements to characterize the instrument performance are reported. It is shown that the measurement results are by and large in agreement with design calculations. New research opportunities with VULCAN are discussed.

scholarly journals Phase diagram of the selfinteracting particle­-antiparticle boson system

2021 ◽  
Vol 29 (1) ◽  
pp. 5-14
Author(s):  
D. Anchishkin ◽  
V. Gnatovskyy ◽  
D. Zhuravel ◽  
V. Karpenko
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Diagrams ◽  
Canonical Ensemble ◽  
Bose Condensate ◽  
Mean Field ◽  
Thermodynamic Quantities ◽  
Boson System ◽  
The Mean

A system of interacting relativistic bosons at finite temperatures and isospin densities is studied within the framework of the Skyrme­like mean­field model. The mean field contains both attractive and repulsive terms. The consideration is taken within the framework of the Canonical Ensemble and the isospin­density dependencies of thermodynamic quantities is obtained, in particular as the phase diagrams. It is shown that in such a system, in addition to the formation of a Bose­Einstein condensate, a liquid­gas phase transition is possible. We prove that the multi­boson system develops the Bose condensate for particles of high­density component only.

scholarly journals Measurement-based modeling of daytime and nighttime oxidation of atmospheric mercury

2017 ◽  
Author(s):  
Maor Gabay ◽  
Mordechai Peleg ◽  
Erick Fredj ◽  
Eran Tas
Keyword(s):  
Lower Limit ◽  
Rate Constant ◽  
Field Measurements ◽  
Elemental Mercury ◽  
Chemical Oxidation ◽  
Atmospheric Mercury ◽  
Gaseous Elemental Mercury ◽  
Measurement Results ◽  
Kinetic Calculations ◽  
First Time

Abstract. Accurate characterization of gaseous elemental mercury (GEM) chemical oxidation pathways and their kinetics is critically important for assessing the transfer of atmospheric mercury to bioaquatic systems. Recent comprehensive field measurements have suggested that the nitrate radical (NO3) plays a role in efficient nighttime oxidation of GEM, and that the role of the hydroxyl radical (OH) as a GEM oxidant has been underestimated. We used the CAABA/MECCA chemical box model and additional kinetic calculations to analyze these measurement results, in order to investigate the nighttime and daytime oxidation of GEM. We assumed a second-order reaction for the NO3 induced nighttime oxidation of GEM. Our analysis demonstrated that nighttime oxidation of GEM has to be included in the model to account for the measured variations in nighttime reactive gaseous mercury (RGM) concentration. A lower limit and best-fit rate constant for GEM nighttime oxidation are provided. To the best of our knowledge, this is the first time that a rate for nighttime oxidation of GEM has been determined based on field measurements. Our analysis further indicates that OH has a much more important role in GEM oxidation than commonly considered. A lower-limit rate constant for the OH–RGM reaction is provided.

scholarly journals Development of a CALPHAD Thermodynamic Database for Pu-U-Fe-Ga Alloys

2019 ◽  
Vol 9 (23) ◽  
pp. 5040 ◽  
Author(s):  
Emily E. Moore ◽  
Patrice E.A. Turchi ◽  
Alexander Landa ◽  
Per Söderlind ◽  
Benoit Oudot ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Density Functional ◽  
Ternary Phase Diagram ◽  
Thermodynamic Database ◽  
Impurity Effects ◽  
Functional Theory ◽  
Formation Enthalpies ◽  
Temperature Ranges ◽  
The Stability ◽  
First Time

The interaction of actinides and actinide alloys such as the δ-stabilized Pu-Ga alloy with iron is of interest to understand the impurity effects on phase stability. A newly developed and self-consistent CALPHAD thermodynamic database is presented which covers the elements: Pu, U, Fe, Ga across their whole composition and temperature ranges. The phase diagram and thermodynamic properties of plutonium-iron (Pu-Fe) and uranium-iron (U-Fe) systems are successfully reassessed, with emphasis on the actinide rich side. Density functional theory (DFT) calculations are performed to validate the stability of the stoichiometric (Pu,U)6Fe and (Pu,U)Fe2 compounds by computing their formation enthalpies. These data are combined to construct the Pu-U-Fe ternary phase diagram. The thermodynamic assessment of Fe-Ga is presented for the first time and application to the quaternary Pu-U-Fe-Ga system is discussed.

scholarly journals Characterization of InGaN/GaN-Based Multi-Quantum Well Distributed Feedback Lasers

1998 ◽  
Vol 537 ◽  
Author(s):  
Daniel Hofstetter ◽  
Robert L. Thornton ◽  
Linda T. Romano ◽  
David P. Bour ◽  
Michael Kneissl ◽  
...  
Keyword(s):  
Ion Beam ◽  
Device Fabrication ◽  
Distributed Feedback ◽  
Coupling Scheme ◽  
Optically Pumped ◽  
Ion Beam Etching ◽  
Measurement Results ◽  
Dfb Laser ◽  
First Time

AbstractWe present a device fabrication technology and measurement results of both optically pumped and electrically injected InGaN/GaN-based distributed feedback (DFB) lasers operated at room temperature. For the optically pumped DFB laser, we demonstrate a complex coupling scheme for the first time, whereas the electrically injected device is based on normal index coupling. Threshold currents as low as 1. 1 A were observed in 500 μm long and 10 μm wide devices. The 3rd order grating providing feedback was defined holographically and dry-etched into the upper waveguiding layer by chemically-assisted ion beam etching. Even when operating these lasers considerably above threshold, a spectrally narrow emission (3.5 Å) at wavelengths around 400 nm was seen.

Dual Wavelength Temperature Monitoring of TBC Coated Alstom 13E2 Turbine Blades

2003 ◽  
Author(s):  
R. A. Rooth ◽  
W. Hiemstra
Keyword(s):  
Temperature Measurement ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Temperature Measurements ◽  
Primary Interest ◽  
Long Wavelength ◽  
Work Related ◽  
Fiber Technology ◽  
Measurement Results ◽  
First Time

Through rapid developments in fiber technology and data acquisition technology, pyrometry has become a successful tool for the measurement of gas turbine blade temperatures. The technology enables gas turbine owners and operators to monitor the blades and to optimise the exploitation of their assets in terms of efficiency and maintenance. With the application of thermal barrier coatings on turbine blades, pyrometry faces a new challenge as these coatings are not opaque at commonly used wavelengths. The application of TBC’s to protect the metal blades allows an increase of the firing temperature, increasing the efficiency of the installation, but is potentially an additional cause of locally overheating blades in the case the coating comes off. The present paper reports on the results of experimental work related to the temperature measurement on an in service Alstom 13E2 turbine with TBC coated first stage blades. Temperature measurements have been performed with both short- and long wavelength instruments (1 μm and 10 μm). The optical characteristics of ZrO2 material at a range of temperatures have been determined. These characteristics are important in the implementation of an algorithm that calculates the metal temperature from the temperature measurement results. These metal temperatures are of primary interest, This is the first time that experimental radiation temperature measurements on an industrial turbine, using both 1 and 10 μm technology, are reported. As the measurement trace over the turbine airfoil consists of areas on the blade that are covered with TBC as well as uncovered areas, a very interesting comparison on the merits of the various systems can be presented.

Thermal Properties of CuGa2 Phase in Inert Atmosphere

2012 ◽  
Vol 326-328 ◽  
pp. 227-232 ◽  
Author(s):  
T.V. Kulikova ◽  
V.A. Bykov ◽  
K. Y. Shunyaev ◽  
A.B. Shubin
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Thermal Decomposition ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Experimental Studies ◽  
Inert Atmosphere ◽  
Heat Conductivity Coefficient ◽  
Incongruent Melting ◽  
Modeling Methods

Thermal decomposition of copper digallide was studied using experimental (thermal analysis) and theoretical (thermodynamic modeling) methods. The temperatures of CuGa2incongruent melting are in satisfactory agreement between experimental and calculated values. Small differences with the phase diagram can be explained by minor non-stoichiometry of the alloy samples. The experimental studies of thermal diffusivity and thermal expansion of CuGa2were performed in the temperature range 298-500 K. The heat conductivity coefficient was further calculated using literary data concerning the density and heat capacity of the copper digallide.

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