Statistical Theories of Binary Ordering
Order–disorder phenomena in alloys and magnetic crystals can be analyzed by statistical theories, assuming that the lattice structure plays no significant role. Lattice vibrations and symmetry are therefore implicit in thermodynamic functions in these theories. Restricted in mean-field accuracy, the statistical theory has only limited access to experimental details, for which a different approach is needed beyond the probability concept. In ordering processes, the lattice stability is an important issue, but statistical theories cannot deal with symmetry changes. Nevertheless, in this chapter, we review existing theories because the probability concept is still useful for simplifying the problem. Characterized by a random process, statistical theories are valid in some aspects of ordering processes, leaving symmetry-related problems to different studies.