Crystallographic shear rutile

An interesting feature to note with regard to crystallographic shear is that even very slightly reduced rutile (e.g. TiO, 997) shows the presence of cs planes. In slowly cooled samples of Ti02 with 0.0 < x 0.01, pairs of cs planes precipitate and separate subsequently (Blanchin et al, 1984). When 0 < x 0.0035, novel 100 platelet defects... 

The simplest member of a shear structure derived from rutile is that found for Tis09 where n = 5. A block of the structure is shown in Figure 15. Here, edge and comer-sharing TiOe blocks of the ratile type, five octahedra thick, are joined by face sharing to similar five unit blocks. As the level of reduction decreases, the size of the ratile block increases but the crystallographic shear remains the same. 

Crystallographic Shear (C5) Phases.—The CS phases are the best-known group of materials which appear to be intolerant of point-defect populations. There are three major families those based upon tungsten trioxide, WO3, upon rutile, Ti02, and upon niobium pentoxide, Nb205. These and other less studied systems have been described in some considerable detail in two previous review articles in this series and elsewhere and the fundamental principles underlying their structures will not be repeated here. In this section some of the results found in the tungsten trioxide and rutile-related systems will be outlined. Older results, covered in the earlier reviews, will merely be sketched in where relevant, and emphasis will be upon newer data or else on a re-examination of earlier results from the point of view of this article. 

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