The document summarizes a seminar on computational thermodynamics and kinetics using Thermo-Calc software. The seminar covered:
1) Fundamentals of thermodynamic assessments including reviewing experimental data and developing thermodynamic models for phases.
2) Composition tuning of high speed steels using computational thermodynamics to predict phase stability and optimize compositions.
3) Development of low-melting point master alloys for powder metallurgy by systematically searching for eutectic compositions.
4) Estimating the lifetime of gas turbine coatings by modeling interdiffusion in multi-component alloys and diffusion kinetics.
Review on recent progress in nitrogen doped graphene synthesis, characterizat...suresh899
This document reviews recent progress in nitrogen-doped graphene, including various synthesis methods and characterization techniques. Some key points:
1. Nitrogen doping introduces pyridinic, pyrrolic, and graphitic nitrogen configurations in graphene which alter its electronic properties.
2. Synthesis methods include CVD, segregation growth, solvothermal, arc discharge, and post-treatment methods like thermal, plasma, and N2H4 treatments.
3. CVD is a common method using metal catalysts and carbon/nitrogen precursors. Other methods include solvothermal reactions and arc discharge of graphite sources.
Review on recent progress in nitrogen doped graphene synthesis, characterizat...materials87
Nitrogen doping has been an effective way to
tailor the properties of graphene and render its potential use
for various applications. Three common bonding configurations
are normally obtained when doping nitrogen into the
graphene: pyridinic N, pyrrolic N, and graphitic N. This paper
reviews nitrogen-doped graphene, including various synthesis
methods to introduce N doping and various characterization
techniques for the examination of various N bonding
configurations. Potential applications of N-graphene are also
reviewed on the basis of experimental and theoretical studies
A review on recent progress in nitrogen doped graphene synthesis, characteriz...Science Padayatchi
1) Nitrogen doping is an effective way to modify the properties of graphene. There are three common types of nitrogen dopants: pyridinic N, pyrrolic N, and graphitic N.
2) Many methods have been used to synthesize nitrogen-doped graphene (N-graphene), including CVD, segregation growth, solvothermal synthesis, and arc discharge. Post-treatment methods include thermal treatment, plasma treatment, and treatment with N2H4.
3) The nitrogen content and dopant configuration in N-graphene can be controlled by parameters like precursor composition, catalyst material, and growth temperature. N-graphene has potential applications in areas like electrocatalysis
This document summarizes a presentation about computing partial charges and molecular charge distributions. It discusses several models:
- The QEq atom-site charge model and its limitations in describing polarizability. Reparameterizing QEq did not improve its accuracy.
- A minimal bond-space charge transfer model that represents charges as charge transfer variables between bonds. This model correctly describes the dissociation of NaCl.
- Quantum analogues of partial charges, including the relationship between orbital energies and discontinuities in total energy from Janak's theorem.
Application Note: Study Rigid Amorphous Fraction in Polymer Nano-Composites b...PerkinElmer, Inc.
It is known that there is a rigid amorphous fraction (RAF) in semicrystalline polymers. The RAF exists at the interface of crystal and amorphous phase as a result of the immobilization of a polymer chain due to the crystal.
Here, heat capacity measurment has been performed in order to detect a possible second Tg on nanocomposites of polymethyl methacrulate (PMMA) with silicon oxide nanoparticles of dfferent shape. StepScan(TM) DSC was used for determination of precise heat capacity and HyperDSC(R) to prevent degradation and identify devitrification of the RAF at elevated temperatures.
Low Temperature Synthesis of Ba3Ta2ZnO9 (BZT) and Ba3Nb2ZnO9 (BZN) by Wet Che...IJASCSE
Powders of high microwave dielectric material Barium Zinc Tantalate (BZT) and Barium Zinc Niobate (BZN) have been prepared by wet chemical procedure at moderately low temperature ~5000C. Co-precipitate and mechanical mixtures of hydroxide of Ba(II), Ta(V)/Nb(V) & Zn(II) in 3:2:1 mole proportion on thermal decomposition, showed formation of the desired perovskite phase at 5000C. The product of co-precipitate and mechanical mixture of hydroxides heated upto7400C produced single phase BZT. Thermal decomposition of mixture was studied in static air atmosphere by TG & DTA. XRD studies on a sample heated to 500, 740, 780 & 9000C confirmed the formation of single phase BZT formation at 7400C and that of BZN at7800C.
This document summarizes ab initio quantum mechanical calculations performed to study the mechanical and thermodynamic properties of calcium carbonate polymorphs, including calcite, aragonite, and vaterite. The calculations were carried out using the CRYSTAL code to determine properties such as lattice parameters, vibrational frequencies, elastic moduli, thermal expansion, and phase transitions at pressures up to 30 GPa and temperatures from 298-700 K. The results from these calculations agree well with available experimental data and provide an exclusive investigation of the properties of calcium carbonate polymorphs.
IB Chemistry Order Reaction, Rate Law and Half lifeLawrence kok
This document provides a tutorial on chemical reaction rates and kinetics concepts including:
- Rate laws and how reaction order is determined experimentally using initial rates or concentration vs. time methods
- Examples of determining the order of reactions with respect to various reactants by varying their concentrations while keeping others fixed
- Graphical representations of zero, first, and second-order concentration profiles over time
- Calculating rate constants from initial rate data and rate laws
- Using half-life to determine first-order behavior with respect to a reactant
Review on recent progress in nitrogen doped graphene synthesis, characterizat...suresh899
This document reviews recent progress in nitrogen-doped graphene, including various synthesis methods and characterization techniques. Some key points:
1. Nitrogen doping introduces pyridinic, pyrrolic, and graphitic nitrogen configurations in graphene which alter its electronic properties.
2. Synthesis methods include CVD, segregation growth, solvothermal, arc discharge, and post-treatment methods like thermal, plasma, and N2H4 treatments.
3. CVD is a common method using metal catalysts and carbon/nitrogen precursors. Other methods include solvothermal reactions and arc discharge of graphite sources.
Review on recent progress in nitrogen doped graphene synthesis, characterizat...materials87
Nitrogen doping has been an effective way to
tailor the properties of graphene and render its potential use
for various applications. Three common bonding configurations
are normally obtained when doping nitrogen into the
graphene: pyridinic N, pyrrolic N, and graphitic N. This paper
reviews nitrogen-doped graphene, including various synthesis
methods to introduce N doping and various characterization
techniques for the examination of various N bonding
configurations. Potential applications of N-graphene are also
reviewed on the basis of experimental and theoretical studies
A review on recent progress in nitrogen doped graphene synthesis, characteriz...Science Padayatchi
1) Nitrogen doping is an effective way to modify the properties of graphene. There are three common types of nitrogen dopants: pyridinic N, pyrrolic N, and graphitic N.
2) Many methods have been used to synthesize nitrogen-doped graphene (N-graphene), including CVD, segregation growth, solvothermal synthesis, and arc discharge. Post-treatment methods include thermal treatment, plasma treatment, and treatment with N2H4.
3) The nitrogen content and dopant configuration in N-graphene can be controlled by parameters like precursor composition, catalyst material, and growth temperature. N-graphene has potential applications in areas like electrocatalysis
This document summarizes a presentation about computing partial charges and molecular charge distributions. It discusses several models:
- The QEq atom-site charge model and its limitations in describing polarizability. Reparameterizing QEq did not improve its accuracy.
- A minimal bond-space charge transfer model that represents charges as charge transfer variables between bonds. This model correctly describes the dissociation of NaCl.
- Quantum analogues of partial charges, including the relationship between orbital energies and discontinuities in total energy from Janak's theorem.
Application Note: Study Rigid Amorphous Fraction in Polymer Nano-Composites b...PerkinElmer, Inc.
It is known that there is a rigid amorphous fraction (RAF) in semicrystalline polymers. The RAF exists at the interface of crystal and amorphous phase as a result of the immobilization of a polymer chain due to the crystal.
Here, heat capacity measurment has been performed in order to detect a possible second Tg on nanocomposites of polymethyl methacrulate (PMMA) with silicon oxide nanoparticles of dfferent shape. StepScan(TM) DSC was used for determination of precise heat capacity and HyperDSC(R) to prevent degradation and identify devitrification of the RAF at elevated temperatures.
Low Temperature Synthesis of Ba3Ta2ZnO9 (BZT) and Ba3Nb2ZnO9 (BZN) by Wet Che...IJASCSE
Powders of high microwave dielectric material Barium Zinc Tantalate (BZT) and Barium Zinc Niobate (BZN) have been prepared by wet chemical procedure at moderately low temperature ~5000C. Co-precipitate and mechanical mixtures of hydroxide of Ba(II), Ta(V)/Nb(V) & Zn(II) in 3:2:1 mole proportion on thermal decomposition, showed formation of the desired perovskite phase at 5000C. The product of co-precipitate and mechanical mixture of hydroxides heated upto7400C produced single phase BZT. Thermal decomposition of mixture was studied in static air atmosphere by TG & DTA. XRD studies on a sample heated to 500, 740, 780 & 9000C confirmed the formation of single phase BZT formation at 7400C and that of BZN at7800C.
This document summarizes ab initio quantum mechanical calculations performed to study the mechanical and thermodynamic properties of calcium carbonate polymorphs, including calcite, aragonite, and vaterite. The calculations were carried out using the CRYSTAL code to determine properties such as lattice parameters, vibrational frequencies, elastic moduli, thermal expansion, and phase transitions at pressures up to 30 GPa and temperatures from 298-700 K. The results from these calculations agree well with available experimental data and provide an exclusive investigation of the properties of calcium carbonate polymorphs.
IB Chemistry Order Reaction, Rate Law and Half lifeLawrence kok
This document provides a tutorial on chemical reaction rates and kinetics concepts including:
- Rate laws and how reaction order is determined experimentally using initial rates or concentration vs. time methods
- Examples of determining the order of reactions with respect to various reactants by varying their concentrations while keeping others fixed
- Graphical representations of zero, first, and second-order concentration profiles over time
- Calculating rate constants from initial rate data and rate laws
- Using half-life to determine first-order behavior with respect to a reactant
This document discusses phase diagrams and related concepts. It begins by asking questions about what equilibrium state and phases result from mixing two elements at a given composition and temperature. It then provides information on phase diagrams, including how they are constructed using cooling curve data from mixtures at different compositions. It discusses rules for determining phase information like number, composition, and amounts from a phase diagram given temperature and composition. Finally, it gives examples of an isomorphous system and eutectic system phase diagram.
Deactivation Modeling through Separable Kinetics of Coking On Ni/CZ Catalyst ...IOSR Journals
Abstract : Steam methane reforming (SMR) is a very significant technique to produce hydrogen from fossil fuels. In this particular work, nickel is used as the active metal and ceria-zirconia (CZ) bi-metallic oxide is used as the support. The foremost challenge to this process is sooting or coking over the catalyst surface and blocking the active sites. For the economic viability of the catalyst, it is very significant to make it coke deposition resistant. This is the reason that the kinetic modeling of the deactivation is very important. Therefore, this paper is aimed to model the deactivation and activity of the catalyst. A rate model of the deactivation process is also developed using separable kinetics. A comparison with commercial catalyst is also reported to show that the Ni/CZ catalyst is much more stable towards the coking. Keywords –Coking, Deactivation, Methane, Separable kinetics, Steam reforming.
Multi-Element Determination of Cu, Mn, and Se using Electrothermal Atomic Abs...IOSR Journals
Simultaneous multi-element graphite furnace atomic absorption spectrometer (SIMAA 6000) is used to get a new multi-element determinations methodology for Cu, Mn, and Se. Firstly, the optimum conditions for single-element mode are determined (which include: pyrolysis and atomization temperatures). Secondly, the optimum conditions for multi-element mode are also determined. The conditions in the two modes have been compared in terms of the characteristic masses, detection limits and pyrolysis and atomization temperatures. The effect of the matrix on the determination has been studied using urine standard sample from Seronorm (LOT 0511545). The accuracy of the developing methods has been confirmed by analysis different biological reference materials. Simultaneous multi-element GF-AAS offers a rapid, low cost and sensitive method for the analysis of trace elements
The document discusses barium perovskites as potential humidity sensing materials. Three key points:
1) Samples of BaMO3 (M=Ti, Zr, Hf, Sn) were prepared via wet chemical synthesis or solid state reaction and tested for their electrical response to humidity.
2) All samples showed an increase in capacitance and conductivity with increasing humidity, indicating interaction between water vapor and the crystal surfaces. Sensitivity was highest at low frequencies and decreased with increasing humidity.
3) Time response to humidity changes was typically 10-100 seconds for intermediate humidity levels. Response time was influenced by the amount of mesopores in the material, with shorter response times associated with less mesoporous
The document discusses phase diagrams, including:
1) Phase diagrams show the phases present in a material at different temperatures and compositions.
2) Binary eutectic systems have a specific eutectic composition that results in the lowest melting temperature. At the eutectic point, the liquid phase transforms directly into two solid phases upon cooling.
3) The copper-silver phase diagram is a binary eutectic system. It has a eutectic point at 779°C and 71.9% silver composition, where the liquid transforms into solid copper and silver phases.
Influence of Trapping on the Recombination Dynamics in Disordered Organic Sem...disorderedmatter
This document summarizes research on the influence of trapping on recombination dynamics in disordered organic semiconductors. Photo-CELIV measurements on annealed P3HT:PCBM blends show that recombination follows reduced Langevin behavior with an order greater than 2, indicating the influence of traps. Analysis fitting the continuity equation to the experimental data supports reduced Langevin recombination over monomolecular or standard Langevin models. The high recombination order is attributed to the influence of trapping on recombination dynamics in these materials.
The document summarizes the synthesis and characterization of bivalent metal chelates of 1,2-naphthoquinone dioxime. Transition metal chelates of the type M[NQO]2 where M=Hg, Cd, Zn, Pb and Ag(NQO) were synthesized. The chelates were characterized using techniques such as elemental analysis, FTIR, electronic spectra, NMR, thermogravimetry, differential scanning calorimetry and electron microscopy. Metal chelates of mercury, lead, zinc and cadmium were found to be octahedral while silver chelate was assigned as square planar. The ligand and metal chelates were screened for antimicrobial
This document presents the theory and simulation of EPR spectra of Cu2+ ions in Cd2(NH4)2(SO4)3 single crystals at different temperatures ranging from 15-180K. The author derives an expression for the derivative line shape function of the EPR spectra accounting for the orthorhombic Jahn-Teller effect of Cu2+. Computer simulation is performed by fitting the line shape function to the observed spectra. The simulation shows excellent agreement and allows extraction of spectroscopic parameters like g-values and hyperfine coupling constants. Analysis of the temperature-dependent spectra provides insight into the Jahn-Teller splitting and dynamics of Cu2+ in this system.
In situ XAFS studies of carbon supported Pt and PtNi(1:1) catalysts for the o...qjia
it\'s a presentation for APS Meeting In Iowa. It mainly introduces our work of rationalizing the superior reactivity of certain commercial alloy nanocatalysts by probing their physical and chemical properties through x-ray experiments and theoretical model simulation.
This document discusses studies of technetium speciation using NMR and EXAFS/XANES spectroscopy during pyrometallurgical reprocessing of spent nuclear fuel. Technetium can form various oxides, oxychlorides, and chlorides of varying volatility depending on processing conditions. NMR was used to characterize technetium metal and EXAFS was used to study technetium halides and complexes. Preliminary results showed EXAFS could distinguish Tc(IV) bromide but further work is needed to characterize lower oxidation states and clusters. The goal is to understand technetium behavior to prevent accumulation and gas releases during reprocessing.
IB Chemistry on Redox Titration, Biological Oxygen Demand and Redox.Lawrence kok
This document provides information on redox titration and calculating the percentage of components in samples. It discusses using potassium permanganate or dichromate to determine the amount of iron in iron pills through redox reactions. An example calculation is shown for finding 91.4% iron in an iron tablet by titrating a solution of the crushed tablet with KMnO4 and calculating the moles of Fe2+. The document also outlines calculations for determining the concentration of hypochlorite in bleach by iodometric titration with thiosulfate and finding 38.4% copper in a brass sample through redox titration.
This document summarizes a benchmark analysis of start-up physics tests performed at the High Temperature Engineering Test Reactor (HTTR). The analysis evaluated cold critical configurations, excess reactivity measurements, shutdown margins, axial reaction rates, and isothermal temperature coefficients. Some challenges included limitations in available public data and conflicting reported values. Overall, there was generally good agreement between benchmark measurements and calculations, though calculations were approximately 2% higher, likely due to uncertainties in graphite composition and cross sections. Completed benchmarks from this analysis will be published in the International Handbook of Evaluated Reactor Physics Benchmark Experiments.
1. The document discusses phase diagrams and thermodynamics of mixing.
2. It explains how phase diagrams can be used to determine the number and types of phases present, the composition of each phase, and the amount of each phase at a given temperature and composition.
3. Binary eutectic and eutectoid systems allow for a range of microstructures depending on the cooling rate, and alloying generally increases strength but decreases ductility due to solid solution strengthening.
The document discusses MOCVD (Metalorganic Chemical Vapor Deposition) technology and material growth. It covers the MOCVD growth system including the reactor, gas handling system, and exhaust system. It also discusses metalorganic compound sources, gas phase and surface reactions during growth, characterization techniques for grown materials, and MOCVD growth of GaN and related materials.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how LDA+U can describe Mott insulators, charge order, spin order, orbital order, and phase transitions. Applications included Fe3O4, KCuF3, Pr1-xCaxMnO3, and LaCoO3. It also introduces the dynamical mean-field theory (DMFT) method, which goes beyond LDA+U by including dynamical correlations. DMFT maps the lattice problem to an effective impurity problem, which can be solved using techniques like quantum Monte Carlo. The document outlines the DMFT self-consistency cycle and implementation of QMC as an impurity solver.
The document discusses Sm-Co permanent magnets, including their properties, manufacturing process, temperature compensated and high temperature grades. It describes the microstructure and thermal stability of Sm-Co magnets. Various applications are mentioned that benefit from Sm-Co magnets' high maximum operating temperatures, corrosion resistance and straight-line demagnetization curves, such as traveling wave tubes, ion propulsion systems and medical devices.
This document discusses opportunities for using nanotechnology to improve energy applications. It notes that nanomaterials have increased surface areas and unique interface and size effects that can be exploited. Examples highlighted include using nanostructures to improve photovoltaics, hydrogen storage, and thermoelectric devices. Challenges include developing scalable synthesis methods and understanding multiscale transport phenomena. Overall, the document argues that nanoscience research has potential to transform energy technologies by manipulating energy carriers at the nanoscale and linking structures to functions.
Master Thesis Total Oxidation Over Cu Based Catalystsalbotamor
The evolution in the oxidation state of Cu and Ce in a benchmark catalyst is studied
under different conditions: temperature programmed reduction with propane and hydrogen,
and isothermal reduction with propane and hydrogen.
Analytical methods used involve operando X-ray absorption spectroscopy (XAS) in
transmission mode at the Cu K edge and Ce LIII edge, as well as online mass spectrometry
(MS) at the outlet of the reactor.
Researchers produced magnesium, magnesium oxide (MgO), and magnesium hydride (MgH2) nanostructures using rapid thermal processing (RTP) to evaluate it as a scalable synthesis method. Electron energy loss spectroscopy (EELS) and X-ray energy dispersive spectroscopy (EDS) confirmed the presence of MgO and possibly MgH2 in the samples. The temperature and atmosphere during RTP affected the morphology and composition of the resulting nanostructures. Higher temperatures produced nanostructures with well-defined facets, while longer hold times allowed structures to fully form. Future work will optimize shape, composition reproducibility, and determine the growth mechanism.
This document summarizes research on thermochemical materials for heat storage. It compares different heat storage systems and discusses the principle and selection of thermochemical heat storage (THSS) materials. The characteristics of SrBr2 and MgSO4 hydrates are described based on thermal analysis. Composites of these materials with activated carbon and expanded natural graphite were manufactured and tested through multiple cycles. The composites showed stable performance over cycles but challenges remain around material stability and geometry changes during cycling. Overall, the research aims to develop low-cost thermochemical materials for seasonal heat storage applications.
This document discusses phase diagrams and related concepts. It begins by asking questions about what equilibrium state and phases result from mixing two elements at a given composition and temperature. It then provides information on phase diagrams, including how they are constructed using cooling curve data from mixtures at different compositions. It discusses rules for determining phase information like number, composition, and amounts from a phase diagram given temperature and composition. Finally, it gives examples of an isomorphous system and eutectic system phase diagram.
Deactivation Modeling through Separable Kinetics of Coking On Ni/CZ Catalyst ...IOSR Journals
Abstract : Steam methane reforming (SMR) is a very significant technique to produce hydrogen from fossil fuels. In this particular work, nickel is used as the active metal and ceria-zirconia (CZ) bi-metallic oxide is used as the support. The foremost challenge to this process is sooting or coking over the catalyst surface and blocking the active sites. For the economic viability of the catalyst, it is very significant to make it coke deposition resistant. This is the reason that the kinetic modeling of the deactivation is very important. Therefore, this paper is aimed to model the deactivation and activity of the catalyst. A rate model of the deactivation process is also developed using separable kinetics. A comparison with commercial catalyst is also reported to show that the Ni/CZ catalyst is much more stable towards the coking. Keywords –Coking, Deactivation, Methane, Separable kinetics, Steam reforming.
Multi-Element Determination of Cu, Mn, and Se using Electrothermal Atomic Abs...IOSR Journals
Simultaneous multi-element graphite furnace atomic absorption spectrometer (SIMAA 6000) is used to get a new multi-element determinations methodology for Cu, Mn, and Se. Firstly, the optimum conditions for single-element mode are determined (which include: pyrolysis and atomization temperatures). Secondly, the optimum conditions for multi-element mode are also determined. The conditions in the two modes have been compared in terms of the characteristic masses, detection limits and pyrolysis and atomization temperatures. The effect of the matrix on the determination has been studied using urine standard sample from Seronorm (LOT 0511545). The accuracy of the developing methods has been confirmed by analysis different biological reference materials. Simultaneous multi-element GF-AAS offers a rapid, low cost and sensitive method for the analysis of trace elements
The document discusses barium perovskites as potential humidity sensing materials. Three key points:
1) Samples of BaMO3 (M=Ti, Zr, Hf, Sn) were prepared via wet chemical synthesis or solid state reaction and tested for their electrical response to humidity.
2) All samples showed an increase in capacitance and conductivity with increasing humidity, indicating interaction between water vapor and the crystal surfaces. Sensitivity was highest at low frequencies and decreased with increasing humidity.
3) Time response to humidity changes was typically 10-100 seconds for intermediate humidity levels. Response time was influenced by the amount of mesopores in the material, with shorter response times associated with less mesoporous
The document discusses phase diagrams, including:
1) Phase diagrams show the phases present in a material at different temperatures and compositions.
2) Binary eutectic systems have a specific eutectic composition that results in the lowest melting temperature. At the eutectic point, the liquid phase transforms directly into two solid phases upon cooling.
3) The copper-silver phase diagram is a binary eutectic system. It has a eutectic point at 779°C and 71.9% silver composition, where the liquid transforms into solid copper and silver phases.
Influence of Trapping on the Recombination Dynamics in Disordered Organic Sem...disorderedmatter
This document summarizes research on the influence of trapping on recombination dynamics in disordered organic semiconductors. Photo-CELIV measurements on annealed P3HT:PCBM blends show that recombination follows reduced Langevin behavior with an order greater than 2, indicating the influence of traps. Analysis fitting the continuity equation to the experimental data supports reduced Langevin recombination over monomolecular or standard Langevin models. The high recombination order is attributed to the influence of trapping on recombination dynamics in these materials.
The document summarizes the synthesis and characterization of bivalent metal chelates of 1,2-naphthoquinone dioxime. Transition metal chelates of the type M[NQO]2 where M=Hg, Cd, Zn, Pb and Ag(NQO) were synthesized. The chelates were characterized using techniques such as elemental analysis, FTIR, electronic spectra, NMR, thermogravimetry, differential scanning calorimetry and electron microscopy. Metal chelates of mercury, lead, zinc and cadmium were found to be octahedral while silver chelate was assigned as square planar. The ligand and metal chelates were screened for antimicrobial
This document presents the theory and simulation of EPR spectra of Cu2+ ions in Cd2(NH4)2(SO4)3 single crystals at different temperatures ranging from 15-180K. The author derives an expression for the derivative line shape function of the EPR spectra accounting for the orthorhombic Jahn-Teller effect of Cu2+. Computer simulation is performed by fitting the line shape function to the observed spectra. The simulation shows excellent agreement and allows extraction of spectroscopic parameters like g-values and hyperfine coupling constants. Analysis of the temperature-dependent spectra provides insight into the Jahn-Teller splitting and dynamics of Cu2+ in this system.
In situ XAFS studies of carbon supported Pt and PtNi(1:1) catalysts for the o...qjia
it\'s a presentation for APS Meeting In Iowa. It mainly introduces our work of rationalizing the superior reactivity of certain commercial alloy nanocatalysts by probing their physical and chemical properties through x-ray experiments and theoretical model simulation.
This document discusses studies of technetium speciation using NMR and EXAFS/XANES spectroscopy during pyrometallurgical reprocessing of spent nuclear fuel. Technetium can form various oxides, oxychlorides, and chlorides of varying volatility depending on processing conditions. NMR was used to characterize technetium metal and EXAFS was used to study technetium halides and complexes. Preliminary results showed EXAFS could distinguish Tc(IV) bromide but further work is needed to characterize lower oxidation states and clusters. The goal is to understand technetium behavior to prevent accumulation and gas releases during reprocessing.
IB Chemistry on Redox Titration, Biological Oxygen Demand and Redox.Lawrence kok
This document provides information on redox titration and calculating the percentage of components in samples. It discusses using potassium permanganate or dichromate to determine the amount of iron in iron pills through redox reactions. An example calculation is shown for finding 91.4% iron in an iron tablet by titrating a solution of the crushed tablet with KMnO4 and calculating the moles of Fe2+. The document also outlines calculations for determining the concentration of hypochlorite in bleach by iodometric titration with thiosulfate and finding 38.4% copper in a brass sample through redox titration.
This document summarizes a benchmark analysis of start-up physics tests performed at the High Temperature Engineering Test Reactor (HTTR). The analysis evaluated cold critical configurations, excess reactivity measurements, shutdown margins, axial reaction rates, and isothermal temperature coefficients. Some challenges included limitations in available public data and conflicting reported values. Overall, there was generally good agreement between benchmark measurements and calculations, though calculations were approximately 2% higher, likely due to uncertainties in graphite composition and cross sections. Completed benchmarks from this analysis will be published in the International Handbook of Evaluated Reactor Physics Benchmark Experiments.
1. The document discusses phase diagrams and thermodynamics of mixing.
2. It explains how phase diagrams can be used to determine the number and types of phases present, the composition of each phase, and the amount of each phase at a given temperature and composition.
3. Binary eutectic and eutectoid systems allow for a range of microstructures depending on the cooling rate, and alloying generally increases strength but decreases ductility due to solid solution strengthening.
The document discusses MOCVD (Metalorganic Chemical Vapor Deposition) technology and material growth. It covers the MOCVD growth system including the reactor, gas handling system, and exhaust system. It also discusses metalorganic compound sources, gas phase and surface reactions during growth, characterization techniques for grown materials, and MOCVD growth of GaN and related materials.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how LDA+U can describe Mott insulators, charge order, spin order, orbital order, and phase transitions. Applications included Fe3O4, KCuF3, Pr1-xCaxMnO3, and LaCoO3. It also introduces the dynamical mean-field theory (DMFT) method, which goes beyond LDA+U by including dynamical correlations. DMFT maps the lattice problem to an effective impurity problem, which can be solved using techniques like quantum Monte Carlo. The document outlines the DMFT self-consistency cycle and implementation of QMC as an impurity solver.
The document discusses Sm-Co permanent magnets, including their properties, manufacturing process, temperature compensated and high temperature grades. It describes the microstructure and thermal stability of Sm-Co magnets. Various applications are mentioned that benefit from Sm-Co magnets' high maximum operating temperatures, corrosion resistance and straight-line demagnetization curves, such as traveling wave tubes, ion propulsion systems and medical devices.
This document discusses opportunities for using nanotechnology to improve energy applications. It notes that nanomaterials have increased surface areas and unique interface and size effects that can be exploited. Examples highlighted include using nanostructures to improve photovoltaics, hydrogen storage, and thermoelectric devices. Challenges include developing scalable synthesis methods and understanding multiscale transport phenomena. Overall, the document argues that nanoscience research has potential to transform energy technologies by manipulating energy carriers at the nanoscale and linking structures to functions.
Master Thesis Total Oxidation Over Cu Based Catalystsalbotamor
The evolution in the oxidation state of Cu and Ce in a benchmark catalyst is studied
under different conditions: temperature programmed reduction with propane and hydrogen,
and isothermal reduction with propane and hydrogen.
Analytical methods used involve operando X-ray absorption spectroscopy (XAS) in
transmission mode at the Cu K edge and Ce LIII edge, as well as online mass spectrometry
(MS) at the outlet of the reactor.
Researchers produced magnesium, magnesium oxide (MgO), and magnesium hydride (MgH2) nanostructures using rapid thermal processing (RTP) to evaluate it as a scalable synthesis method. Electron energy loss spectroscopy (EELS) and X-ray energy dispersive spectroscopy (EDS) confirmed the presence of MgO and possibly MgH2 in the samples. The temperature and atmosphere during RTP affected the morphology and composition of the resulting nanostructures. Higher temperatures produced nanostructures with well-defined facets, while longer hold times allowed structures to fully form. Future work will optimize shape, composition reproducibility, and determine the growth mechanism.
This document summarizes research on thermochemical materials for heat storage. It compares different heat storage systems and discusses the principle and selection of thermochemical heat storage (THSS) materials. The characteristics of SrBr2 and MgSO4 hydrates are described based on thermal analysis. Composites of these materials with activated carbon and expanded natural graphite were manufactured and tested through multiple cycles. The composites showed stable performance over cycles but challenges remain around material stability and geometry changes during cycling. Overall, the research aims to develop low-cost thermochemical materials for seasonal heat storage applications.
The document summarizes a workshop on limiting factors in high temperature electrolysis. It discusses environmental and resource concerns motivating hydrogen production from electrolysis. Renewable and nuclear energy could power electrolysis to produce hydrogen for storage or conversion to synthetic fuels. Key challenges include electrolyzer durability, thermodynamics, heat management, and costs. Large-scale electrolysis tests demonstrate feasibility but further advances are needed for commercialization.
1) Magnesium ion batteries have several advantages over lithium ion batteries including higher natural abundance, lower cost, and greater safety.
2) This document describes a high-voltage magnesium-sodium hybrid battery using a Na3V2(PO4)3 cathode and magnesium anode that achieves a voltage of 3.5 V and capacity retention of 80% over 50 cycles.
3) It also presents a new design for an aqueous magnesium ion battery using a LiVP cathode and PPMDA anode that achieves high voltage of 3 V and capacity retention of 80% over 100 cycles.
Thermal Modeling of Electron Beam Additive Manufacturing Process–Powder Sinte...Ninggang Shen
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Poznań ACE event - 19.06.2024 Team 24 Wrapup slidedeck
Thermo-Calc Workshop Madrid 2010
1. Seminar in Computational Thermodynamics & Kinetics
with Thermo-Calc Software
Madrid, 1-2 June, 2010
Computational Thermodynamics
applied to powder metallurgy
Dr. Tomás Gómez-Acebo
2. Outline
• The fundamentals: assessments
• Composition tuning of a high speed steel
• Development of master alloys for powder
metallurgy
• Life of Gas Turbine coatings
4. Thermodynamic assessment
• Review of literature
data:
– Phase diagram:
compositions, T, solu
bility…
– Chemical thermo:
, a, cp, H, …
– Crystallography
• Thermodynamic
model of each phase
• Reproduce
experimental data
The natural way of understanding thermodynamic models
5.
6.
7. Thermodynamic models: Gibbs energy
E
Gm xAg GAg x Zn GZn RT xAg ln xAg x Zn ln x Zn Gm
Gref (mechanical Sid (configurational
mixture) entropy)
Gid (ideal solution)
Excess Gibbs energy: Redlich-Kister polynomials
2
E 0 1 2
Gm xAg x Zn LAg,Zn LAg,Zn xAg x Zn LAg,Zn xAg x Zn
Each phase is modelled separatedly
9. COMPOSITION TUNING OF A
HIGH SPEED STEEL
V. Trabadelo, S. Giménez, T. Gómez-Acebo and I. Iturriza, “Critical assessment of
Computational Thermodynamics in the alloy design of PM high speed steels”.
Scripta Materialia, 53 (3) 287-292 (2005). doi:10.1016/j.scriptamat.2005.04.017
10. Sintering of high speed steels
• Complex chemistry:
– Fe-Cr-Mo-Co-V-W-C-N
– High C content: carbides
• Optimum Sintering Temperature (OST)
– Effect of C, N and
sintering atmosphere
– L+fcc+carbides
– Avoid cementite
– Liquid phase sintering
12. M35MHV: identification of the stable
phases
All phases in SSOL Only observed phases: L, bcc ( ),
Including gas, MC=(Mo,W)C fcc ( and MX), M6C, M3C, Fe2MoC ( )
13. M35MHV: effect of C and N
Fe–1.80C–4.0Cr–5.4Mo–5.5Co–0.035N–4.2V–
6.0W–0.06O, with C additions, sintered in
90N2-9H2-1CH4
100 ppm N 7000 ppm N
Narrow sintering window Wider sintering window
14. M42HVIG vs M35MHV
• New experimental HSS: M42HVIG
HSS C N* O* Cr Co Mo V W Si Fe
M35MHV 1.82 350 600 4.00 5.50 5.40 4.20 6.00 - Bal.
M42HVIG 1.48 221 484 4.08 8.50 10.1 5.29 - 0.41 Bal.
wt.-%, * ppm
• Reasonable to consider the same set of
phases, rejecting the remaining phases:
– L, bcc ( ), fcc ( and
MX), M6C, M3C, Fe2MoC ( )
15. M42HVIG with 1.1 wt.% N
Sintered in 90N2-9H2-1CH4
• Discrepancies in Solidus
temperature:
– Calculated: 1136 ºC
– Experimental: 1156 ºC
• Correct prediction of
microstructure (sintering at
OST=1210 ºC): carbides
Measured N: 1.14 wt.%
16. Change in carbide morphology with C
content
M42HVIG + 0.4% C M42HVIG + 0.7% C
• Higher C content -> change in morphology of
bright carbides
• Evolution from cubic M6C to hexagonal M2C
20. Why is M2C observed in M42HVIG and
not in M35MHV?
• Mo and W have a similar role in
HSS: formation of M6C carbide
• Equivalent Mo content:
M Mo
we (Mo) w(Mo) w( W )
MW
• Driving force for precipitation of
M2C at 1150 ºC
• Constant equivalent Mo:
we(Mo) = 10%
• High positive value: less stable
21. Conclusions
• For well-known systems: calculations with
few phases
• Computer-aided design of HSS: accurate
selection of phases involved
• Sintering behaviour of well-studied systems
should not be automatically extrapolated for
new compositions
22. DEVELOPMENT OF MASTER
ALLOYS FOR P/M
T. Gómez-Acebo, M. Sarasola and F. Castro, “Systematic search of low melting
point alloys in the Fe-Cr-Mn-Mo-C system”. Calphad, 27 (3) 325-334 (2003).
doi:10.1016/j.calphad.2003.12.001
23. Master alloys
• Pre-alloyed powders added to promote
densification
• In liquid phase sintering: liquid formation at
“low” temperatures
• Enhances diffusion of chemical elements
• Alloy design: systematic search of low
melting point alloys
• Study of liquidus surface, liquidus
monovariant lines
25. Ternary Al-Mg-Zn
Red arrow:
lowest eutectic
temperature
Liquidus surface: Two projections of the liquidus monovariant
projection onto the lines of the Al-Mg-Zn system onto
composition axis. temperature-composition planes. Minimum
liquidus temperature: 338 ºC for 3.97Al-
49.0Mg-47.0Zn (in wt-%).
26. Ternary Al-Mg-Zn
0
340ºC
HEAT FLOW (W/g)
-1 -phase
and
MgZn
-2
Mg
-3
250 300 350 400 450
T (ºC)
DSC analysis of an SEM micrograph of the Al-Mg-Zn
experimentally obtained alloy alloy with minimum liquidus
with composition close to that temperature, showing the
with minimum liquidus identified phases.
temperature.
27. Ternary Al-Cu-Mg
Projections of the liquidus monovariant lines.
Liquidus surface
0
Minimum liquidus temperature: 425 ºC for
428ºC
32.5Al-4.29Cu-63.2Mg (in wt-%).
HEAT FLOW (W/g)
-1
AlMg- hcp(Mg)
-2 Q-phase
-3
350 400 450 500
T (ºC)
DSC analysis alloy with
composition close to that with
minimum liquidus temperature.
28. Quaternary Al-Cu-Mg-Zn
Projections of the liquidus monovariant lines onto the temperature-
composition planes for part of the quaternary Al-Cu-Mg-Zn system. Cu
additions to the ternary do not reduce the liquidus temperature of the Al-Mg-
Zn eutectic.
31. Ternary Fe-Mn-C
DSC and TG analyses of an Optical micrograph of the C-Fe-Mn
experimentally obtained alloy with alloy with minimum liquidus
composition close to that with minimum temperature, showing eutectic
liquidus temperature structure of fcc+M3C.
32. Quinary C-Cr-Fe-Mn-Mo system
• Quaternary C-Fe-
Mn-Mo system.
• “1”: eutectic with
lowest T:
– 1309 K (1036 ºC)
– Fe-4C-21Mn-
10Mo
• Quinary C-Cr-Fe-Mn-Mo
system.
• Cr additions to the
quaternary do not
reduce the liquidus
temperature of the
eutectic.
33. Note on calculation of liquidus
monovariant lines in multicomponent
systems
• With Thermo-Calc, currently a 5-dimension diagram
can be calculated.
– The first two axis variables can be any property
considered as a condition (i.e. composition of two
components)
– The other axes have to be potentials (temperature
and activity of the other components).
• The calculation proceeds when the diagram is
calculated starting from an invariant point.
• Extremely sensitive to starting point of calculation.
34. Binary Mn-Ni
• Intermediate phases not included in databases
35. Conclusions
• Calculation like those presented here allow
the systematic search of liquid phases in the
whole composition range.
• Projections onto a temperature vs
composition plane allow easy identification of
multicomponent eutectic points.
• Experimentally obtained alloys in the Al-Mg-
Zn, Al-Cu-Mg and Fe-Mn-C ternary systems
have allowed verification of the theoretical
predictions for the eutectic temperatures.
36. LIFE ESTIMATION OF GAS
TURBINE OVERLAY COATINGS
T. Gómez-Acebo, B. Navarcorena and F. Castro, “Interdiffusion in multiphase, Al-
Co-Cr-Ni-Ti diffusion couples”. Journal of Phase Equilibria and Diffusion, 25 (3) 237-
251 (2004). http://dx.doi.org/10.1007/s11669-004-0112-y
37. Introduction
• GT blades: coatings of
oxidation-resistant alloys:
– MCrAlY: M=Ni,Co,Fe
– Pt-Aluminides
• Life of the coating: loss of
oxidation resistance
38. Introduction
• Coating: -fcc + -B2
– : bond coat (diffusion)
– : Al reservoir
• Loss of oxidation resistance: Al
– Oxidation: growth of oxide layer
– Spallation: loss of oxide layer
– Inward diffusion of Al
– Outward diffusion of Ni etc:
depletion of .
39. Objectives
• Diffusion in ternary and multicomponent Al-
Co-Cr-Ni-Ti alloys
• Review of thermodynamic and kinetic data
• Lifetime estimation of MCrAlY coatings
40. Materials and experimental procedure
Alloy Preparation Diffusion couples
• Mixture of high-purity metals: • Al-Co-Cr /
Al, Co, Cr, Ni, Ti. + /
• Uniaxially pressed at 400 MPa. • Al-Co-Ni / + ’
• Furnace melt at Tliq+200 K in Ar. • Al-Co-Cr-Ni + /
• Homogenisation 3h, 1100 ºC in • Al-Co-Cr-Ni-Ti + /
Ar. + / +Ni3Ti
• Diffusion annealing: 1100 ºC,
24-72 h
• Diffusion profiles: EDAX
41. Thermodynamic description
• TCNI1 database [N. Dupin and B. Sundman, "A thermodynamic
database for Ni-base superalloys", Scan. J. Metall., 30, 184-192
(2001)].
• All binaries assessed
• Assessed ternaries:
– Al-Co-Ni
– Al-Cr-Ni
– Al-Cr-Ti
– Al-Ni-Ti
– Cr-Ni-Ti
• Non-assessed ternaries:
– Al-Co-Cr
– Al-Co-Ti
– Co-Cr-Ni
– Co-Cr-Ti
– Co-Ni-Ti
42. Thermodynamic data of Al-Co-Cr
Calculations from
the three binaries
(no ternary
parameters)
Experimental data
[K. Ishikawa et al,
"Phase equilibria
and stability of the
BCC aluminide in
the Co-Cr-Al
system", Ber.
Bunsenges. Phys.
Chem., 102, 1206-
1210 (1998)].
Unrealistic data for
solvus line / +
43. Al-Co-Cr alloys
Co-5.0Al-25.7Cr
f =0.06 (meas.)
f =0.03 (calc.)
Co-6.0Al-27.9Cr
f =0.24 (meas.)
f =0.23 (calc.)
Calculations from the binaries
(no ternary parameters)
Good agreement for +
region Co-7.7Al-32.0Cr
GT29: a commercial MCrAlY f =0.59 (meas.)
coating: Co-6Al-29Cr-[0.5Y] f =0.51 (calc.)
44. Kinetic description
• Ni-database [C. E. Campbell, W. J. Boettinger, and U. R.
Kattner, "Development of a diffusion mobility database for Ni-
base superalloys", Acta Mat., 50, 775-792 (2002)].
• Assessed sub-systems:
– Al-Cr Non assessed sub-systems:
– Al-Ni • Al-Co
• Co-Cr
– Al-Ti
• Co-Ti
– Co-Ni • Cr-Ti
– Cr-Ni • Other ternary sub-systems
– Ni-Ti
– Al-Cr-Ni Diffusion only in -fcc phase
– Al-Ni-Ti
45. Kinetic description (fcc phase)
M i0 Qi 1 Qi*
• Atomic mobilities: Mi exp exp
RT RT RT RT
Qi* Qi RT ln( M i0 )
• Redlich-Kister polynomials:
Qi* x j Qi j xp x j k
Aipj ( x p x j )k
j p j p k
Ti Ni
• Accepted approximations: QAl QAl
Cr Cr
QCo Q Ni
Ti Co
QCo QCo
Ti Ni
QCr QCr
Al Co Ti Ni
QTi QTi QTi QTi
Cr Cr
QTi QAl
Ti Ni
Q Ni Q Ni
Co Fe
QAl 5QFe
46. Diffusion in Al-Co-Cr ( / couples)
C1: Co-4.2Al / Co-8.9Cr C2: Co-4.0Al / Co-14.1Cr
1100 ºC, 72 h 1100 ºC, 72 h
47. Diffusion in Al-Co-Cr ( + / couples)
C3: Co-8.2Al / Co-11.1Cr C4: Co-9.1Al / Co-17.0Cr C5:Co-10.0Al / Co-30.0Cr
1100 ºC, 72 h 1100 ºC, 72 h 1100 ºC, 72 h
48. Diffusion in Al-Co-Cr ( + / couples)
Original interface
C4: Co-9.1Al / Co-17.0Cr
Regression of phase + <
49. Diffusion in Al-Co-Ni ( / + ’ couples)
C6: Ni-5Al-30Co / Ni-10Al-23.3Co
1100 ºC, 48 h
> + ’
Original interface
50. Diffusion in Al-Co-Cr-Ni ( + / couples)
C9: Co-5Al-25.7Cr / Ni-6.5Al-40.8Co
1100 ºC, 72 h
+ <
C10: Co-6Al-27.9Cr / Ni-5.5Al-39.8Co
1100 ºC, 72 h
+ <
C11: Co-7.7Al-32Cr / Ni-5Al-38Co
1100 ºC, 72 h
+ <
55. Lifetime estimation of GT coatings
• Al loss is due to three factors:
– Interdiffusion
– Oxidation
– Spallation (only in discontinuous
operation)
• Highest rate: interdiffusion
• Possible criteria for lifetime estimation of the coating:
– Loss of phase in the coating
– Depletion of phase in the coating surface
– Depletion of Al in the coating surface: formation of a stable
oxide
56. Lifetime estimation of GT coatings
Depletion of -phase
1150
GT29 100/200 m 1100
Temperature (ºC)
1050
CMSX-4 4 mm 1000
950
900 100 m
200 m
850
1 month 1 year 10 years
800
1.E+05 1.E+06 1.E+07 1.E+08 1.E+09
time (s)
57. Conclusions
• Review of thermodynamic and kinetic data
– Al-Co-Cr: good predictions from the binaries
– Kinetic data needed for Co
• Analysis of the diffusion paths:
– Good prediction for Al
– Good prediction for depletion of -phase
– Other elements (Cr, Ni): not satisfactory
predictions
• Lifetime estimation of the coatings:
interdiffusion