Disorder in solids

Materials that contain defects and impurities can exhibit some of the most scientifically interesting and economically important phenomena known. The nature of disorder in solids is a vast subject and so our discussion will necessarily be limited. The smallest degree of disorder that can be introduced into a perfect crystal is a point defect. Three common types of point defect are vacancies, interstitials and substitutionals. Vacancies form when an atom is missing from its expected lattice site. A common example is the Schottky defect, which is typically formed when one cation and one anion are removed from fhe bulk and placed on the surface. Schottky defects are common in the alkali halides. Interstitials are due to the presence of an atom in a location that is usually unoccupied. A... 

Catlow C R A 1994. An Introduction to Disorder in Solids, hi NATO ASl Series C 418 [Defects and Disorder in Cnfstalline and Amorphous Solids), pp. 1-23. 

Lennard-Jones, J., and A. Devonshire. 1939. Critical and Co-operative Phenomena IV. A Theory of Disorder in Solids and Liquids and the Process of Melting. Proc. R. Soc. London, Ser. A, Vol. 170, 464. 

V. F. Gantmakher, Electrons and Disorder in Solids (translated from Russian by L. I. Man), International Series of Monographs on Physics 130, Oxford University Press, New York, 2005, p. 225. 

Isotopic disorders (e.g. in solid chlorine atoms 35C1 and 37C1 isotopes can arise) and nuclear spin degeneracy (ortho and para hydrogen) are two rather less important factors which can also give rise to residual disorder in solids at 0 K. 

N. G. Parsonage and L. A. K. Staveley, Disorder in Solids (Oxford University Press, Oxford, 1978)... 

Figure 9.11. Generation of disorder in solids by a cascade of collisions (schematically).

The concepts of enthalpy (H) and entropy (S) are basic to the definitions of Gibbs free energy, chemical potential, and the equilibrium constant (K ), and allow us to predict the effect of temperature on G and Kg. We will also see that entropy is a measure of the state of order-disorder in solids and solid solutions, and helps explain the stabilities of aqueous complexes. 

In this review, we attempt to present the subject of solid mesophases of polymers mainly in relation to structural aspects emerging from diffraction experiments. The relationships between the structure and properties of these materials are analyzed and related to the amount and kind of disorder present in the crystals. The study of disorder in solid mesophases, indeed, allows a deep comprehension of phenomena subtending their chemical and physical properties. 

Entropy generally inaeases with incaeasing temperature. Further, the entropies of the phases of a given substance follow the order Ssoua < liquid < Sg s- This ordering fits in nicely with our picture of the relative degrees of disorder in solids, liquids, and gases. — (Section 11.1)... 

The empirical phase of the development of solid electrolyte fuel cells was overcome only after many general advances in research on solids. These included development of X-ray structure analysis, new knowledge on the ion conduction of solids from the measurements of transport numbers by Tubandt (first detection of unipolar conduction by anions), the establishment of the theory of disorder in solids by Frenkel, Schottky, Wagner and Jost, and the development of isotope methods for the investigation of diffusion processes in solids. 

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