Micro-twin structures

the regularly spaced twinning operation to the HCP lattice produces a new type of structure having trigonal prism interstices in the region of the 

Compounds with micro-twin structure derived from 

Next we discuss the micro-twin structure derived from a CCP lattice. Using the hexagonal expression, the CCP structure is composed of layer stacking... ABCABC. .. along the Ch(, -axis (= The ortho-hexagonal 

In Fig. 2.73 is shown the structure of CrB, which is a typical example of (1, IjccpCCrP B ). The compound YOOD has an anti-CrB type structure as expressed by (1, l)ccpY O OP D, where half of the prismatic sites are occupied by Y. Table 2.3 shows some examples of micro-twin structure related to CCP. 

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We shall discuss first the micro-twin structure derived from an HCP lattice. Figure 2.54(a) shows a projection of HCP on (OOI)hcp. In Fig. 2.54(b) the ortho-hexagonal axes c<,, ) are shown as well as the usual hexagonal... 

It is convenient to draw micro-twin structures derived from the micro-twinning of a CCP lattice projected on the normal plane to the pillars of the trigonal prisms. Let us consider a twin structure derived from a NaCl-type structure, in which both anions and cations have a CCP arrangement. Figure 2.67 shows the structure of a NaCl-type (a) is projected on (OOl)Naci and (b) on (110). It can be easily shown that the twin plane (203) ,j in the ortho-hexagonal expression corresponds to the (113) plane in the cubic one. Figure 2.68 shows a twin structure of NaCl-type,... 

We shall now present studies relating to the micro-twin structure performed by B. G. Hyde, who is a main proposer of the concepts of shear and micro-twin structures. One study is on the mineral humite family,the composition of which is generally expressed by nMg2SiO4-Mg(OH)2 (this has to be altered to nMg2SiO4-Mg(OH, F)2, because (OH) is often replaced by F in the minerals). In Table 2.4, the mineral name, together with the compositions and micro-twin structures proposed by the authors, are collected, the space group is Pmcn (orthorhombic) for n = odd and... 

Minerals ofhumite family with micro-twin structure ... 

White and Hyde extended their observations to the manganohumite family (Mg is replaced by Mn in humite) and leucophoenicite 3Mn2SiO4-Mn(OH)2 and obtained fruitful results from the viewpoint of the micro-twin structure. 

The structures described in this chapter, especially on micro-twin structure, are referred to in Inorganic crystal structures by B. G. Hyde and S. Andersson. ... 

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