Materials kinetics thermodynamics

Improvement in metal hydride hydrogen storage has been slow in achieving the targets needed for several applications. But slow, steady progress is foreseen as material processing in the nano-range improves the kinetics, thermodynamics, and capacity of the metal hydride systems so that they become acceptable for some applications perhaps for stationary systems. 

In this course we will need to use material from thermodynamics, heat transfer, mass transfer, fluid mechanics, and especially chemical kinetics. We assume that the student has had some exposure to these topics, but we will attempt to define concepts when needed so that those unfamiliar with particular topics can still use them here. 

Bruno, J., Casas, I., Cera, E., Swing, R. C., Finch, R. C. Werme, L. O. 1995. The assessment of the long-term evolution of the spent nuclear fuel matrix by kinetic, thermodynamic and spectroscopic studies of uranium minerals. Materials Research Society Symposium Proceedings, 353, 633-639. 

In the study of materials science, two broad topics are traditionally distinguished thermodynamics and kinetics. Thermodynamics is the study of equilibrium states in which state variables of a system do not change with time, and kinetics is the study of the rates at which systems that are out of equilibrium change under the influence of various forces. The presence of the word dynamics in the term thermodynamics is therefore misleading but is retained for historical reasons. 

Because of the importance of microstructure on dielectric and ferroelectric properties, the transformation pathway associated with conversion of the amorphous film into the crystalline state has been studied extensively. The basic mechanism involved is one of nucleation and growth, although the formation of intermediate phases that can impact the thermodynamic driving forces associated with the transformation frequently occurs. " Another key aspect of CSD films is that crystallization occurs well below the melting point of the materials. Therefore, compared to standard mixed-oxide processing of bulk materials, the thermodynamic driving forces associated with the transformation are much greater and the kinetics of mass transport are much less. 

Solid-state electrochemistry is an important and rapidly developing scientific field that integrates many aspects of classical electrochemical science and engineering, materials science, solid-state chemistry and physics, heterogeneous catalysis, and other areas of physical chemistry. This field comprises - but is not limited to - the electrochemistry of solid materials, the thermodynamics and kinetics of electrochemical reactions involving at least one solid phase, and also the transport of ions and electrons in solids and interactions between solid, liquid and/or gaseous phases, whenever these processes are essentially determined by the properties of solids and are relevant to the electrochemical reactions. The range of applications includes many types of batteries and fuel cells, a variety of sensors and analytical appliances, electrochemical pumps and compressors, ceramic membranes with ionic or mixed ionic-electronic conductivity, solid-state electrolyzers and electrocatalytic reactors, the synthesis of new materials with improved properties and corrosion protection, supercapacitors, and electrochromic and memory devices. 

W. Weppner, Solid State Electrochemical Methods for the Characterization of the Kinetics, Thermodynamics and Phase Equilibria of Lithium Battery Materials, in C. JuUen, Z. Stoynov (Eds.), Materials for Lithium-Ion Batteries, Kluwer Academic Publishers, Dordrecht, NL, 2000, p. 451. 

The ORR catalysts are used in either acidic or basic electrolyte solutions, and when they are used in either acidic or alkaline fuel cells in the presence of high oxidizing oxygen, electrochemical stabilities of both the catalysts and their support materials are very important for their practiced applications. In the presence of O2, the potential of electrode coated with a catalyst (or the catalyst s potential) will be higher than 1.2 V vs RHE. This potential is higher than the oxidation potentials of almost all metal and carbon materials, or in other words, almost all metal and carbon materials are thermodynamically unstable in the sense of electrochemistry. However, due to the slow kinetics of the oxidation process, or the oxidation product is less soluble, the carbon and Pt-based materials can still be used as ORR catalysts for fuel cells even at acidic or basic environment and high temperatures such as 70-80 °C. 

The most common thermodynamic quantities that we will encounter in our exploration of materials kinetics are enthalpy (//), entropy (5), and Gibbs free energy (G). Usually we are concerned with quantifying the changes in these thermodynamic functions (i.e., AH, AS, AG) during a process of reaction rather than the absolute values. Changes in thermodynamic functions are always calculated as final state - initial state. 

Revision of Material on Thermodynamics and Kinetics For the eighth edition, we completely revised all the thermodynamics data used in the book, making sure that it is accurate and up-to-date. Also, the discussion of entropy in Chapter 19 was rewritten to present entropy as a measure of the dispersal of energy. 

Recent studies have resulted in significant advances in the understanding of the thermodynamics of drying hygroscopic materials, kinetics of drying, evaporation... 

Rong-zu Hu (1938-) Chin, chem., thermodynamics of energetic materials, kinetics of exothermic decompositions Rouquerol Jean ( 1937-) Fr. chem., microcalorimetry, adsorption, co-inventor of sample controlled thermal analysis Rowland Henry Augustus (1848—1901) Amer. phys., gave mechanical equivalent of heat and of the ohm, studied magnetic action due to electric convection (book Elements of Physics 1900)... 

The only practical way of achieving complete chemical conversion of the raw material without thermodynamic or kinetic limitations is to carry out the chemical processes with recycling of the unreacted raw material. 

Transition-metal nanophases are intrinsically unstable materials (the thermodynamic minimum appears always to correspond to the bulk metal) that we can handle, store and use for technological applications exclusively in case the kinetics of their undesired degradation reactions are sufficiently slow. In aiming to slow down the rate of NP side reactions, a large number of investigations have been conducted to determine how the correct stabilization of metal NPs can be achieved. 

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