Growth defects in cultured quartz: a microscopic investigation

In some crystals, various types of defects are observed which can limit the performances of piezoelectric devices. Two distinct modes of water incorporation have been recognized, namely molecular water (tiny fluid inclusions with diameters down to 30 AA) and isolated point defects like the so-called 4H/sub Si/ defects. The equilibrium concentration of this latter type of defects is extremely low at the usual T and P conditions of growth, but a supersaturation can occur for relatively large growth rates. The equilibrium concentration was determined as a function of T and P, and the diffusivity coefficient of the corresponding water species as a function of temperature was tentatively estimated.<>