Perfection of quartz and its connection to crystal growth.

The perfection of cultured quartz and its connection to growth processes is reviewed. The principal macroscopic imperfection, ;creative flawing', is shown to be the hydrothermal crystal growth analog of dendritic growth and can be eliminated by the proper choice of growth direction and manipulation of conditions to minimize the effects of diffusion. Acoustic loss (1/Q) is proportional to the infrared absorption at the OH stretch frequency and is most likely due to a small (a few hundred molecules) number of aggregates of H(2)O, although lesser quantities of OH, which charge-compensate Al(+3) and Fe(+3) at Si(+4) sites, are also present. Techniques for preparing cultured quartz with Q equivalent to the best natural quartz are now routine. Radiation hardness is discussed in terms of impurity content. Impurity-decorated dislocations are shown to be the most probable cause of latent etch channels. Dislocations propagate from the seed but may be initiated by particulate inclusions and/or lattice parameter mismatch between the growth and the seed. Dislocation-free material can be grown by seed selection and procedures that eliminate inclusions.