Process and apparatus for producing single crystals

摘要

Single crystal production apparatus comprises a crucible with an interspace between a seed channel and a reduced cross-section portion (11) of a crystal seed (9). Apparatus for single crystal production comprises a crucible with a first portion and a smaller cross-section seed channel-forming second portion (6). A crystal seed (9), having a first portion (10) and a smaller cross-section second portion (11), is positioned in the seed channel (6) such that its second portion (11) faces the first crucible portion and an interspace exists between the inner wall of the seed channel and at least the second seed portion (11) so that the latter stands free in the seed channel. Independent claims are also included for the following: (i) single crystal production using the above apparatus, in which only the interspace is filled with a liquid oxidic melt (14) such as B2O3; and (ii) single crystal production using a thermal shock resistant crystal seed having a dislocation density of 10000-100000/cm<2>.