Thermodynamic Basis of Crystal Growth: P-T-X Phase Equilibrium and Non-Stoichiometry

ISBN-13: 9783540412465 / Angielski / Twarda / 2001 / 251 str.

Jacob Greenberg

Opis

It is particularly symptomatic that a volume concerning P-T-X phase equilibrium should appear in the Materials Science Series. Entering the 21st century, progress in modern electronics is increasingly becoming associated with devices based not only on silicon but also on chemical compounds. These include both semiconduc- tors and, in the last 15 years, multinary oxides with high-To superconductor properties. The critical role of chemical processes in the technologies of these materials is quite evident, and in recent years has stimulated vigorous research activity in the physical chemistry of materials, resulting in a renaissance of this field. The leading role in these efforts belongs to thermodynamics, in particular, computer modeling of chemical processes, phase equilibrium, and controlled synthesis of inorganic materials with preliminary fixed stoichiometric composition. Especially important contributions have been made regarding non- stoichiometry and our understanding of the crucial relationship between composition and properties of the materials since the development of the vapor pressure scanning approach to the phenomenon of non-stoichiometry. This method of the in situ investigation of the crystal composition directly at high temperatures 3 4 proved to be of an unparalleled precision of 10- _10 at. % and made it possible to obtain in an analytical form functional dependences of the crystal composition on temperature, pressure, and composition of the crystallizing matrix for crystals with sub-O. l at. % range of existence.

Recenzje

"We recommend this book to any physicist concerned with phase diagrams and to any materials scientist concerned with semiconducting compounds."

--Physicalia

Spis treści

1 Thermodynamic Fundamentals.- 2 Experimental Methods of Investigating P-T-X Phase Equilibrium.- 3 Experimental Data on P-T-X Phase Diagrams and Non-stoichiometry.- Conclusion.- References.

Blurb

The properties of some inorganic materials (semiconductors, and high-Tc superconductors, in particular) are strongly dependent on the composition of the crystal, whereas the homogeneity range, or the maximum non-stoichiometry of the solid, is very often less than the precision of the conventional analytical methods (roughly 0.1 at.%). Consequently, new and more sensitive methods must be developed to probe the non-stoichiometry. For many types of materials vapor pressure scanning can be such a technique. This method was developed by the author, and it is a way of determining the composition of the solid, X, at the measured temperature, T, and pressure, P, with an unparalleled accuracy of up to 10-4 at.% at high temperatures (up to 1200° C). Along with the results obtained by the author and his colleagues, P-T-X diagrams of other important materials (e.g. III-V, IV-VI semiconductors) are also discussed. The exposition is in two parts. In the first one a geometrical thermodynamic approach is used for a step-by-step presentation of P-T-X diagrams of binary systems. The types of diagrams most frequently encountered in materials science are discussed. The composition of crystals grown from various matrices is presented in conjunction with the P-T-X diagrams. In the second part examples of systems which have been recently experimentally studied are given. Throughout the book emphasis is placed on the Phase Rule argument of universal solubility. This is where this book differs from the other (quite scarce) texts on P-T-X phase diagrams. This book will be of interest to the wide community of materials scientists, and to university lecturers and their students.