Particle coherent

In supported catalysts there is evidence that particle morphology is affected by the nature of the support, and by the methods of preparation and pretreatment. Coalescence and reconstruction of clean particles should be extremely rapid. The fact that in many cases small particles in contact do not combine into a single coherent particle suggests that the surface of supported metal particles may be relatively highly contaminated. When this occurs it must affect catalytic properties and correlations between activity and structure. 

The precipitate in a Ce-Co-Cu-Fe sample was identified by Leamy and Green (1973) as very small (10 nm), coherent particles of 2-17 phase. Hofer (1970) reported for Sm-Co-Cu alloys a separation into a SmCo5 phase with some Cu in solution and a Co-modified SmCu5 phase. This was said to come about by spinodal decomposition around the composition of SmCo3Cu2 where the coercive force... 

PRESERVATION OF LOCAL COHERENCE Particles in a solid Molecules Supercond. Atoms in... 

Fig. 1.11. Coherent and semi-coherent particles. The symbol L in subfigure (b) denotes inserted half-planes of the lattice. The edge where such a half-plane ends is called an edge dislocation. This will be discussed in section 6.2...

Depending in the crystal structure of the two phases, the interface between them may adopt different structures If the crystal structures and the crystal orientation of both phases are identical and the lattice constants do not differ too much, the particles of the second phase will be coherent i. e., the lattice planes of the matrix continue within the particle (see figure 1.11(a)). If the lattice structure and orientation are identical, but the lattice constants differ strongly, the particles will be semi-coherent because some lattice planes of the matrix continue inside the particle but others do not (figure 1.11(b)). Generally, the crystal lattice is distorted near to the coherent or semi-coherent particle. If the lattice structure of both phases or the lattice orientation differ, the particles are incoherent the lattice planes of particle and matrix have no relation at all (figure 1.12). 

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