Characterization of synthetic quartz crystals grown from cylindrical seedsproduced by ultrasonic machining

The potential of ultrasonic machining is investigated as a tool to produce seed crystals for hydrothermal growth of synthetic quartz with required sur face finish and unconventional geometries. For this purpose, cylindrical se eds with 5, 10 and 18 mm diameter were obtained along the optic axis of a Z -bar using a conventional ultrasonic machining process with abrasive partic les ranging from 6 to 50 mum. The topography of seed surfaces was character ized by surface profilometry and scanning electron microscopy. Later, synth etic crystals were grown in a standardized hydrothermal growth condition us ing NaOH solution. The characterization of as-grown crystals was performed by double-crystal Xray topography with Laue geometry. Based on X-ray topogr aphic images, it was observed that the density of dislocations, nucleated a t the early stage of the growth period, increases with increasing roughness of the seed-crystal surface. (C) 2001 Elsevier Science B.V. All rights res erved.