Solid solution classification

The situation in the solid state is generally more complex. Several examples of binary systems were seen in which, in the solid state, a number of phases (intermediate and terminal) are formed. See for instance Figs 2.18-2.21. Both stoichiometric phases (compounds) and variable composition phases (solid solutions) may be considered and, as for their structures, both fully ordered or more or less completely disordered phases. This variety of types is characteristic for the solid alloys. After a few comments on liquid alloys, particular attention will therefore be dedicated in the following paragraphs to the description and classification of solid intermetallic phases. 

Clear-liquor advance from what is called a double draw-off crystallizer is simply the removal of mother liquor without simultaneous removal of crystals. The primary action in classified-fines removal is preferential withdrawal from the crystallizer of crystals of a size below some specified value this may be coupled with the dissolution of the crystals removed as fines and the return of the resulting solution to the crystallizer. Classified-product removal is carried out to remove preferentially those crystals of a size larger than some specified value. In the following discussion, the effects of each of these selective removal functions on crystal size distributions will be described in terms of the population density function n. Only the ideal solid-liquid classification devices will be examined. It is convenient in the analyses to define flow rates in terms of clear liquor. Necessarily, then, the population density function is defined on a clear-liquor basis. 

Even with such a classification, some difficulty arises in assigning certain defect solids to one class or another. There can be no dispute that defects of the Schottky and Frenkel type in stoicheiometric crystals are thermal in origin there can equally be no dispute that the stoicheiometric dual-valency compounds are biograpliical, but the situation with regard to non-stoicheiometric compounds and anomalous solid solutions of various types is by no means as clear. Various authors have stated that non-stoicheiometric compounds are biographical in type this is incorrect, as the departure from stoicheiometry (or inversely the range of existence of a non-stoicheiometric phase) is a function of temperature which tends to zero as For example, zinc oxide... 

Scorr, K. M. 1987. Solid solution in, and classification of, gossan-derived members ol the alunite-jarosite family, northwest Queensland, Australia, Am. Mineral. 72 178-87,... 

Although the geometrical picture of interstitial structures presented above provides a convenient basis for their classification, and is, indeed, the origin of the very name by which they are known, it must not be assumed that these structures can be regarded simply as interstitial solid solutions in the crystal structure of the parent metal. There are many reasons for this view, among which the following may be mentioned ... 

In this section the results on high-spin iron(II) systems are presented before those on iron(III). The latter dominate, and are ordered approximately as follows the major structural classes of Fe203/M203 solid solutions, MFe03 perovskites, MFe03 orthoferrites, M3FesOi2 garnets and other iron(III) oxides approximately in the periodic table classification of the second metal. Any quaternary oxides are included with the most appropriate ternary system. 

The RbH2P0/,-NH/.H >P0/ -H20 system. The solubility In this system has been measured only at 298 K (5). There are legitimate questions about the analytical procedures used in this work and the results must be considered to be questionable. There Is considerable scatter in the data, which are plotted on Figure 1. It appears that one series of solid solutions is formed. Figure 1 shows that they b nog to Type I in the Roozeboom classification (9). 

Fig. 2.4 Classification scheme for binary titanium alloy phase diagrams—an alternative to the scheme in Fig. 2.3. a and P are hep and bcc solid-solution alloys, respectively, and Y represents an intermetallic compound [Mol65, p. 154].

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