Gliding behavior

Conjugate behavior occurs in TiC. In this case, at the cores of glide dislocations, the octahedral array of Ti-atoms changes to approximately hexagonal prismatic, so the coordination number of the C-atoms changes from eight to six. 

It may be apparent from studying the perovskite structure that it is likely to exhibit quite anisotropic plastic (hardness) behavior, and it does. The primary glide plane is (110) and the glide direction is (1-10). 

The observant reader will undoubtedly have noted that no evidence of any stereochemical nonrigidity (on the NMR time scale) has been obtained for any of the mononuclear complexes derived from OFCOT. However, the dinuclear complex 88 does exhibit fluxional behavior (151). If the solid-state structure of 88 were rigidly maintained in solution, the 19F-NMR spectrum should show eight resonances due to symmetry inequivalent fluorines. However, only four broad resonances are present in the 19F NMR spectrum at room temperature, indicative of a dynamic process that interconverts the two enantiomorphs of 88. Two mechanisms have been proposed for such interconversions in COT analogues a glide and a twitch (Scheme 3). The... 

The observed mircrostructures and rheological behavior are consistent with the suggestion by Durham, Goetze, and Blake (1977) that the dislocations glide essentially unhindered by other dislocations and that deformation is limited by the number of active dislocation sources. 

Two structures have been proposed for (Gly) I an antiparallel-chain pleated sheet (APPS) and a similar rippled sheet (APRS) (see Section III,B,1). These structures have different symmetries the APPS, with D2 symmetry, has twofold screw axes parallel to the a axis [C (a)] and the b axis [C (b)], and a twofold rotation axis parallel to the c axis [62(0)] the APRS, with C2h symmetry, has a twofold screw axis parallel to the b axis ( 2(6)], an inversion center, i, and a glide plane parallel to the ac plane, o-Sj. Once these symmetry elements are known, together with the number of atoms in the repeat, it is possible to determine a number of characteristics of the normal modes the symmetry classes, or species, to which they belong, depending on their behavior (character) with respect to the symmetry operations the numbers of normal modes in each symmetry species, both internal and lattice vibrations their IR and Raman activity and their dichroism in the IR. These are given in Table VII for both structures. 

Just as a gliding air-hockey puck models a reboimding gas particle, Figure 10.7 shows that marbles in a beaker model some behaviors of liquids. When liquids form puddles, interparticle forces maintain their volmne but not their shape. The particles of a liquid can slide past each other, but they are so close together that they don t move as straight or as smoothly as an air-hockey puck. When you try to walk across a crowded sidewalk, you can t move quickly in a straight line, either. 

According to figs. 10a and 10b, the stress exponents where calculated from the slope of the creep stress vs. strain rate curves. The n value for creep of the Ti5Si3 compound is n=3.0 0.2. This predicts a power law creep behavior based on viscous glide of dislocations sustained by diffusion... 

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