Morphology twinning

The morphology, twinning, and optical orientation of gismondine were studied by [80N1]. 

Fig. 5. Silver haUde grain morphologies for (a) cubic, precipitated in an environment having a silver ion concentration, [Ag" ], of ca 2.5 x 10 mol/L (b) octahedral, ca 6.0 x 10 mol/L and (c) tabular microcrystals, ca 1.0 x 10 ° mol/L. A cross section of a tabular grain revealing double parallel twin planes...

The tensile properties of the extruded blends and composites are presented in Table 2. Compared to the neat PP, a clear reinforcement was achieved after twin-screw blending. The reinforcing effect was even more pronounced with the higher take-up speed (H), evidently due to the extremely fibrillar morphology, as seen in Fig. 3. 

Huneault, M. A., Shi, Z. H., and Utracki, L. A., Development of polymer blend morphology during compounding in a twin-screw extruder. Part IV A new computational model with coalescence. Polym. Eng. Sci. 35(1), 115-127 (1995). 

The water and A1 contents decrease while the amount of M cations per unit cell of zeolite increases. For Li and Na,the morphology consists of clusters of polycrystalline aggregates. Better outlined single crystals are observed for K and Rb and additional pronounced twinning appears for (Cs)ZSM-5 (Figure 10). 

By means of our experimental method (twin+single crystal kinetics) steady state growth morphology can be predicted as a function of supersaturation and temperature. 

The basic morphologies of lepidocrocite are lath-like or tabular. No example of twinning has been reported. Macrocrystalline lepidocrocite in the form of tabular crystals has 010 as the predominant form (Fig. 4.13). Other massive varieties of lepidocrocite include micaceous and fibrous textures and aggregated scales. 

The commonest habits for hematite crystals are rhombohedral, platy and rounded (Fig. 4.19). The plates vary in thickness and can be round, hexagonal or of irregular shape. Under hydrothermal conditions, these three morphologies predominate successively as the temperature decreases (Rosier, 1983). The principal forms are given in Table 4.1. Hematite twins on the 001 and the 102 planes. The crystal structure of hematite has a less directional effect on crystal habit than does that of goethite and for this reason, the habit of hematite is readily modified. A variety of morphologies has been synthesized, but in most cases, the crystal faces that enclose the crystals have not been identified. 

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