Solid state, description

Cartensen JT, Li Wan Po A. The stale of water in drug decomposition in the moist solid state. Description and modeling. Ini J Pharm 1992 83 87-94. 

Indeed, it is a typical nanoscale problem, since locating up to 4,500 iron centers and their associated oxide and hydroxide oxygen atoms is not really feasible, while a powder pattern for such a small portion of an iron(III) oxyhydroxide mineral (which is probably also disordered) is not going to give much information on the detailed structure either, i.e., it lies between the molecular and solid-state descriptions. 

Unlike the solid state, the liquid state cannot be characterized by a static description. In a liquid, bonds break and refomi continuously as a fiinction of time. The quantum states in the liquid are similar to those in amorphous solids in the sense that the system is also disordered. The liquid state can be quantified only by considering some ensemble averaging and using statistical measures. For example, consider an elemental liquid. Just as for amorphous solids, one can ask what is the distribution of atoms at a given distance from a reference atom on average, i.e. the radial distribution function or the pair correlation function can also be defined for a liquid. In scattering experiments on liquids, a structure factor is measured. The radial distribution fiinction, g r), is related to the stnicture factor, S q), by... 

NMR basic principles and progress specialised monograph giving detailed descriptions of specific areas of solid state NMR. 

The fluid mechanics origins of shock-compression science are reflected in the early literature, which builds upon fluid mechanics concepts and is more concerned with basic issues of wave propagation than solid state materials properties. Indeed, mechanical wave measurements, upon which much of shock-compression science is built, give no direct information on defects. This fluids bias has led to a situation in which there appears to be no published terse description of shock-compressed solids comparable to Kormer s for the perfect lattice. Davison and Graham described the situation as an elastic fluid approximation. A description of shock-compressed solids in terms of the benign shock paradigm might perhaps be stated as ... 

Given the advanced state of wave-profile detectors, it seems safe to recognize that the descriptions given by such an apparatus provide a necessary, but overly restricted, picture. As is described in later chapters of this book, shock-compressed matter displays a far more complex face when probed with electrical, magnetic, or optical techniques and when chemical changes are considered. It appears that realistic descriptive pictures require probing matter with a full array of modern probes. The recovery experiment in which samples are preserved for post-shock analysis appears critical for the development of a more detailed defective solid scientific description. 

Conventional physical descriptions of materials in the solid state are concerned with solids in which properties are controlled or substantially influenced by the crystal lattice. When defects are treated in typical solid state studies, they are considered to modify and cause local perturbations to bonding controlled by lattice properties. In these cases, defect concentrations are typically low and usually characterized as either point, linear, or higher-order defects, which are seldom encountered together. 

It is indeed a distressing prospect to contemplate the complications introduced by chemical changes into an otherwise orderly physical description. The chemical complications are intimately intertwined with the mechanical and physical effects, which are already understood to be more complex than present theory indicates. As the questions addressed in solid state chemistry are quite different from those addressed in prior work, new approaches are required to develop a scientific understanding of the field. 

Shock-compressed solids and shock-compression processes have been described in this book from a perspective of solid state physics and solid state chemistry. This viewpoint has been developed independently from the traditional emphasis on mechanical deformation as determined from measurements of shock and particle velocities, or from time-resolved wave profiles. The physical and chemical studies show that the mechanical descriptions provide an overly restrictive basis for identifying and quantifying shock processes in solids. These equations of state or strength investigations are certainly necessary to the description of shock-compressed matter, and are of great value, but they are not sufficient to develop a fundamental understanding of the processes. 

Shock-induced solid state chemistry represents the most complex fundamental problem ever encountered in shock-compression science. All the mechanical and physical complications of other work are present, yet the additional chemical complications are added. Indeed, all mechanical, physical, and chemical aspects of the problem are intimately intertwined. Chemical investigations promise to provide a description of shock compression that differs considerably from that to which we have become accustomed. Nevertheless, a full description of the process requires contributions from a number... 

Following the general trend of looldng for a molecular description of the properties of matter, self-diffusion in liquids has become a key quantity for interpretation and modeling of transport in liquids [5]. Self-diffusion coefficients can be combined with other data, such as viscosities, electrical conductivities, densities, etc., in order to evaluate and improve solvodynamic models such as the Stokes-Einstein type [6-9]. From temperature-dependent measurements, activation energies can be calculated by the Arrhenius or the Vogel-Tamman-Fulcher equation (VTF), in order to evaluate models that treat the diffusion process similarly to diffusion in the solid state with jump or hole models [1, 2, 7]. 

Models for description of liquids should provide us with an understanding of the dynamic behavior of the molecules, and thus of the routes of chemical reactions in the liquids. While it is often relatively easy to describe the molecular structure and dynamics of the gaseous or the solid state, this is not true for the liquid state. Molecules in liquids can perform vibrations, rotations, and translations. A successful model often used for the description of molecular rotational processes in liquids is the rotational diffusion model, in which it is assumed that the molecules rotate by small angular steps about the molecular rotation axes. One quantity to describe the rotational speed of molecules is the reorientational correlation time T, which is a measure for the average time elapsed when a molecule has rotated through an angle of the order of 1 radian, or approximately 60°. It is indirectly proportional to the velocity of rotational motion. 

These limitations, most urgently felt in solid state theory, have stimulated the search for alternative approaches to the many-body problem of an interacting electron system as found in solids, surfaces, interfaces, and molecular systems. Today, local density functional (LDF) theory (3-4) and its generalization to spin polarized systems (5-6) are known to provide accurate descriptions of the electronic and magnetic structures as well as other ground state properties such as bond distances and force constants in bulk solids and surfaces. 

Here we briefly summarize some major results of solid state theory that are relevant for understanding the behavior of adsorption on surfaces. For a more detailed description please consult excellent books such as S. Elliot, The Physics and Chemistry of Solids (1998), Wiley Sons, New York N. Ashcroft and N.D Mermin, Solid... 

Solid solutions are very common among structurally related compounds. Just as metallic elements of similar structure and atomic properties form alloys, certain chemical compounds can be combined to produce derivative solid solutions, which may permit realization of properties not found in either of the precursors. The combinations of binary compounds with common anion or common cation element, such as the isovalent alloys of IV-VI, III-V, II-VI, or I-VII members, are of considerable scientific and technological interest as their solid-state properties (e.g., electric and optical such as type of conductivity, current carrier density, band gap) modulate regularly over a wide range through variations in composition. A general descriptive scheme for such alloys is as follows [41]. 

It is probably true that many of the descriptions of physical and solid state reaction mechanisms now existing in the literature are only partially correct. It would appear that part of the frontier of knowledge for Chemistry of The Solid State wiU lie in measurement of physical and chemical properties of inorgcuiic compounds as a function of purity. 

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