scholarly journals Effects of Zr Addition on Thermodynamic and Kinetic Properties of Liquid Mg-6Zn-xZr Alloys

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 607
Author(s):  
Ye Yuan ◽  
Yuan Huang ◽  
Qiang Wei
Keyword(s):  
Diffusion Coefficients ◽  
Formation Enthalpy ◽  
Ternary Alloys ◽  
Kinetic Properties ◽  
Free Energies ◽  
Zr Addition ◽  
Data Points ◽  
Thermodynamic Effects ◽  
Kinetic Effects ◽  
Mixing Enthalpies

Mg-6Zn-xZr (ZK60) alloys are precipitation strengthened by Mg-Zn intermetallics. Therefore, it is important to investigate the thermodynamic and kinetic effects of Zr addition on formations of these reinforcement phases (Mg7Zn3, MgZn2, and MgZn) in Mg-6Zn-xZr melts. Because it is difficult to gain thermodynamic and kinetic data in melts by experiment, obtaining these data points still depends on a theoretical calculation. Based on the Miedema formation enthalpy model and the Chou model, the thermodynamic properties (the mixing enthalpies, the Gibbs free energies, and the component activities) of Mg-6Zn-xZr ternary alloys and their constitutive binary alloys are calculated. The thermodynamic effects of Zr addition on formations of Mg7Zn3, MgZn2, and MgZn are predicted. Using a ternary model for predicting diffusion coefficients, the diffusion coefficients of Zn and Zr in liquid Mg-6Zn-xZr alloys are calculated and the kinetic effects of Zr addition on the diffusion coefficient of Zn is discussed. The results show that the Zr addition can hinder the formations of Mg7Zn3, MgZn2, and MgZn inter-metallics in thermodynamics and kinetics.

Estimation of Li-Ion Diffusion Coefficients in C60 Coated Si Thin Film Anodes Using Electrochemical Techniques

2012 ◽  
Vol 326-328 ◽  
pp. 87-92 ◽  
Author(s):  
Arenst Andreas Arie ◽  
Joong Kee Lee
Keyword(s):  
Thin Films ◽  
Diffusion Coefficients ◽  
Electrochemical Impedance ◽  
Silicon Film ◽  
Electrochemical Techniques ◽  
Lithium Ion ◽  
Chemical Vapor ◽  
Film Coating ◽  
Kinetic Properties ◽  
Silicon Thin Films

C60coated Si thin films were prepared sequentially by a plasma enhanced chemical vapor deposition and a plasma assisted thermal evaporation technique. The films were then utilized as anode materials for lithium ion batteries. The diffusion coefficients of Li-ions in the film electrodes were then estimated by typical electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. The diffusion coefficients determined by both methods were found to be consistent each other. The diffusion coefficient of coated samples was obviously higher than that of bare silicon thin films, indicated that the kinetic properties of lithium ion transport in silicon film electrodes were enhanced by the C60film coating on its surface.

Some thermodynamic and kinetic properties of H2SO4–H3PO4–H2O–Fe(III) system

2021 ◽  
pp. 1-9
Author(s):  
Ya.G. Avdeev ◽  
Keyword(s):  
Diffusion Coefficients ◽  
Arrhenius Equation ◽  
Platinum Electrode ◽  
Molar Fraction ◽  
Redox Couple ◽  
Kinetic Properties ◽  
Cyclic Voltammogram ◽  
Electrode Potentials ◽  
Half Wave ◽  
Sulfate Complexes

The values of the electrode potentials of the redox couple Fe(III) / Fe(II) and the half-wave potentials of the reactions Fe3+ + e– = Fe2+ и Fe2+ — e– = Fe3+ on the cyclic voltammogram of a platinum electrode in acid solutions containing Fe(III) salts have been measured to characterize the oxidizing ability of the H2SO4—H3PO4—H2O—Fe(III) system. The values of these experimentally obtained parameters are close. A decrease in the oxidizing ability of H2SO4 and H3PO4 mixtures containing Fe(III) with an increase in the molar fraction of H3PO4 in them occurs due to the formation of Fe(III) complexes with phosphate anions which are inferior to their hydrate and sulfate complexes in the oxidizing ability. The temperature coefficients of the electrode potential (dE / dt) of the redox couple Fe(III) / Fe(II) in the H2SO4—H2O, H2SO4—H3PO4—H2O and H3PO4–H2O systems were determined experimentally. The diffusion coefficients of Fe(III) in the studied solutions were calculated based on the Randles—Shevchik equation. The temperature dependence of the diffusion coefficients of Fe(III) cations is satisfactorily described by the Arrhenius equation. The parameters of this equation are calculated.

Dependence of Shape and Geometry of Microelectrodes in Manipulating Polarizable Particles like DNA through Electro-kinetic Effects

2016 ◽  
Vol 66 (4) ◽  
pp. 307 ◽  
Author(s):  
Sudarshan Ghonge ◽  
Souri Banerjee
Keyword(s):  
Aqueous Solution ◽  
Electric Field ◽  
Kinetic Properties ◽  
Molecular Wire ◽  
Dna Molecules ◽  
Electro Osmosis ◽  
Patterned Electrodes ◽  
Kinetic Effects

<p>Recently electro-kinetics, namely AC electro-osmosis and dielectrophoresis have been judiciously utilised to manipulate movement of polarizable particles like DNA suspended in aqueous solution and placed between electrically fed microelectrodes. Researchers around the globe have tried to fabricate electrodes of different geometries to understand how electric field owing to sharpness of the electrodes has influenced the aforementioned electro-kinetic properties. In this review, we have presented a chronological development indesign of patterned electrodes used to align and trap DNA molecules in and around the electrodes. We have examined the pros and the cons of such geometry of the set of the micro-electrodes and also tried to provide a solution in terms of shape and sharpness of the electrode that would facilitate DNA molecules to bridge between the electrodes for further application of conducting DNA as molecular wire. </p>

Studies on the iodide–triiodide equilibrium

1977 ◽  
Vol 55 (5) ◽  
pp. 792-797 ◽  
Author(s):  
Robert L. Benoit ◽  
Michael F. Wilson ◽  
Sing-Yeung Lam
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Gas Phase ◽  
Formation Enthalpy ◽  
Aprotic Solvents ◽  
Free Energies ◽  
Potentiometric Measurements ◽  
Cast Doubt ◽  
Transfer Parameters ◽  
The Enthalpy Of Formation

The solvent effect on the iodide–triiodide equilibrium has been investigated by means of calorimetric and potentiometric measurements. The aprotic solvents studied were nitromethane, nitrobenzene, sulfolane, acetonitrile, propylene carbonate, acetophenone, dimethylformamide, dimethylsulfoxide, and o-dichlorobenzene. The resulting enthalpy and free energy changes imply that the variations of the enthalpies and free energies of transfer of the iodide and triiodide ions probably are small and that there is an important non-coulombic contribution to these transfer parameters. Values were obtained for the enthalpy of formation of two solid triiodides, which together with values for other triiodides, cast doubt on reported calculated lattice enthalpies of triiodides and formation enthalpy of I3− ion in the gas phase. This latter formation enthalpy is found to be, from our solution data, more negative than −22 kcal mol−1.

scholarly journals Determination of Grain Boundary Diffusion Coefficients in C-Regime by Hwang-Balluffi Method: Silver Diffusion in Pd

2009 ◽  
Vol 289-292 ◽  
pp. 763-767 ◽  
Author(s):  
Z. Balogh ◽  
Z. Erdélyi ◽  
Dezső L. Beke ◽  
Alain Portavoce ◽  
Christophe Girardeaux ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Controlled Processes ◽  
Diffusion Controlled ◽  
Arrhenius Function ◽  
Data Points ◽  
Accumulation Kinetics

Diffusion controlled processes play a crucial role in the degradation of technical materials. At low temperatures the most significant of them is the diffusion along grain boundaries. In thin film geometry one of the best methods for determining the grain boundary (GB) diffusion coefficient of an impurity element is the Hwang-Balluffi method, in which a surface sensitive technique is used to follow the surface accumulation kinetics. Results of grain boundary diffusion measurements, carried out in our laboratory by this method in three different materials systems (Ag/Pd, Ag/Cu and Au/Ni) are reviewed. In case of Ag diffusion along Pd GBs the surface accumulation was followed by AES method. The data points can be well fitted by an Arrhenius function with an activation energy Q=0.99eV

scholarly journals A Role for DPPX Modulating External TEA Sensitivity of Kv4 Channels

2008 ◽  
Vol 131 (5) ◽  
pp. 455-471 ◽  
Author(s):  
Olaia Colinas ◽  
Francisco D. Pérez-Carretero ◽  
José R. López-López ◽  
M. Teresa Pérez-García
Keyword(s):  
Kinetic Properties ◽  
Scaffolding Proteins ◽  
Physiological Properties ◽  
Kv4 Channels ◽  
Voltage Dependent ◽  
Oxygen Sensitive ◽  
K Current ◽  
Chemoreceptor Cells ◽  
Heterologous Expression Systems ◽  
Kinetic Effects

Shal-type (Kv4) channels are expressed in a large variety of tissues, where they contribute to transient voltage-dependent K+ currents. Kv4 are the molecular correlate of the A-type current of neurons (ISA), the fast component of ITO current in the heart, and also of the oxygen-sensitive K+ current (KO2) in rabbit carotid body (CB) chemoreceptor cells. The enormous degree of variability in the physiological properties of Kv4-mediated currents can be attributable to the complexity of their regulation together with the large number of ancillary subunits and scaffolding proteins that associate with Kv4 proteins to modify their trafficking and their kinetic properties. Among those, KChIPs and DPPX proteins have been demonstrated to be integral components of ISA and ITO currents, as their coexpression with Kv4 subunits recapitulates the kinetics of native currents. Here, we explore the presence and functional contribution of DPPX to KO2 currents in rabbit CB chemoreceptor cells by using DPPX functional knockdown with siRNA. Additionally, we investigate if the presence of DPPX endows Kv4 channels with new pharmacological properties, as we have observed anomalous tetraethylammonium (TEA) sensitivity in the native KO2 currents. DPPX association with Kv4 channels induced an increased TEA sensitivity both in heterologous expression systems and in CB chemoreceptor cells. Moreover, TEA application to Kv4-DPPX heteromultimers leads to marked kinetic effects that could be explained by an augmented closed-state inactivation. Our data suggest that DPPX proteins are integral components of KO2 currents, and that their association with Kv4 subunits modulate the pharmacological profile of the heteromultimers.

Phase Field Simulation of Coarsening Kinetics in Al-Sc and Al-Sc-Zr Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
H. Zapolsky ◽  
J. Boisse ◽  
R. Patte ◽  
N. Lecoq
Keyword(s):  
Phase Field ◽  
Diffusion Coefficients ◽  
Three Dimensional ◽  
Ternary Alloys ◽  
Simulation Results ◽  
Coarsening Kinetics ◽  
Two Phases ◽  
Kinetics Of ◽  
Good Agreement ◽  
Zr Alloys

AbstractThe coarsening kinetics of γ’ precipitates in binary and ternary Al3Sc1-xZrx alloys is studied by using the two- and three-dimensional phase-field simulations. Our focus is on the influence of diffusion coefficients of Sc and Zr atoms on the transformation path kinetics from disordered f.c.c. matrix to two phases equilibrium state with γ’ precipitates and f.c.c. disordered matrix. Our simulation results demonstrate that in the case of binary alloys taking into account the concentration dependence of the mobility of atoms decreases the coarsening rate. In the case of ternary alloys we show that the Al3Sc particles precipitate first following by appearance of a Zr-rich shell. Our simulations results are in good agreement with experimental observations.

Thermochemistry in the system Cu–In–S at 723 K

1994 ◽  
Vol 9 (1) ◽  
pp. 125-131 ◽  
Author(s):  
H. Migge ◽  
J. Grzanna
Keyword(s):  
Thin Film ◽  
Free Energy ◽  
Solar Cells ◽  
Formation Enthalpy ◽  
Thin Film Solar Cells ◽  
Free Energies ◽  
Base Materials ◽  
Gibbs Triangle ◽  
Standard Formation Enthalpy ◽  
New Literature

A thermochemical analysis is performed in the system Cu-In-S at 723 K. Free energies of In6,S7, In417S583, “In2S3”, Cu951In49, and CuIn5S8 have been estimated, the numerical values (kJ/mol) of which are −1285, −97 780, −481.1, −31 680, and −1444. The free energy (kJ/mol) of CuInS2 is calculated from the relation G° = (-306.1 ± 54.4) + 0.5092T −1.397 10−5T2 −0.09468T In T + 268.2T−1, which is obtained from published assessed standard formation enthalpy and specific heat and entropy data. The free energy of the Cu-In melt is taken from very new literature. A consistent set of data is used for the calculation of a tentative Gibbs triangle as well as of the corresponding predominance area diagram. The Gibbs triangle is calculated with the program thermo, the algorithm of which is given. The results are in agreement with the results of published measurements, also for the equilibria which involve the melt. The compound CuInS2, one of the possible base materials for thin film solar cells, is shown to equilibrate with most of the compounds of the system. Predictions are made how to prepare CuInS2 from Cu-In alloys and H2S/H2 gas mixtures. However, more experiments are necessary to establish the data, the experiments, and/or the results of the calculations.

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