REGIME, HYDRAULIC GLIDE CONTROL
At intermediate temperatures, the regime that prevails is known as hydraulic glide control regime. At such higher temperature compared to that of the intrinsic regime, the Peierls barriergets lowred because of the presence of water. This allows the dislocation to move without being hindered. Presence of water therefore facilitates the movement of dislocations through nucleation and propagation of kinks since the temperature is optimum. Water also takes part in aiding the nucleation of kinks and to some extent their propagation. A steady state or constant strain rate creep is therefore difficult to be achieved during the hydraulic glide controlled regime.
Plastic deformation generally takes place by intracrystalline slip which in turn depends upon the temperature, Coble Creep, Nabarro Herring Creep and glide controlled creep and finally by deformation induced twinning. The dislocation moves with the help of all or some of these mechanisms. If the movement of the dislocation is hampered by an energy barrier known as Peierls barrier. This regime which is generally a low temperature regime is known as intrinsic regime. At low to moderate temperature, the Peierls barrier of quartz is very high. Despite the fact that water content may be high, in this regime quartz remains very strong and does not deform plastically.
REGIME, RECOVERY CONTROLLED
This is the regime at very high temperatures. Peierls barrier is almost absent if water is available in sufficient quantities. Transmission electron microscope studies of synthetic quartz points to te fact that at low temperatures the dislocations are generally straight and lie along simple crystallographic directions but under high temperature regime, the dislocations are commonly curved in the form of dislocation loops with many such loops which do not lie in a single plane. The dislocations may also "climb" at high temperature and twinning may become a common feature.