Problems of Bi_4Ge_3O_12 and Li_2B_4O_7 single crystal growth by crusibleless vawriant of AHP method

摘要

The application of the crucibless method for the grwoth of dielectric crstal from the melt is studied. This method is a variant of crystal growth in an axial heat flux close to the pahse interface (AHP method). A special AHP-heater placed in the melt close to hte growing crystal allowed the creation of a phlanar interface over practically the whole cross section. This scheme gave an opportunity to cotnrol the temeprature gradient in the melt close to the interaece over a wide range (from 10 up to 200 K/cm). Problems of crystal growth: holding o the melt laeyr with the rqueired thickness by surface tension forces; supply of charge to the AHP-heater and feeding melt to the growing crystal; adjustment of crystallizer are considered. The conditions of morphologicla instabiltiy of the interface are found for LBO crystal. It was determined that crystallographic direcion of facets boudnign the cells is the same as those forming the crystal habitus.