Mass Transport and Heat Transfer

Abstract

Macroscopic mass and heat transport play a central role in crystal growth processes. Before “molecules proceed from a position in the fluid medium, just outside the crystal-fluid interface, to their (relatively) permanent resting place in the crystal surface” [5.1], i.e., before molecules are “attached” to the crystal, they must typically be transported in the fluid over macroscopic distances towards the interface. This transport can be either fast or slow compared to the attachment kinetics. Then the rate with which a crystal grows is limited by interfacial kinetics or by the macroscopic transport, respectively. Interfacial growth mechanisms and their kinetics are the subject of later chapters. In this chapter we concern ourselves with the macroscopic transport part of crystal growth processes. Emphasis is put on the fundamentals of the various transport modes, their distinction and interplay. The general concepts obtained will then be applied to more specialized configurations and geometries in the later chapters on segregation, morphological stability, and growth from melts, vapors and solutions.