METHOD OF GROWING LITHIUM TRIBOLATE CRYSTAL (OPTIONS) Russian patent published in 2019 - IPC C30B9/12 C30B17/00 C30B27/02 C30B15/14 C30B15/22 C30B15/36 C30B29/22 G02F1/355 G02F1/37 

FIELD: chemistry.

SUBSTANCE: invention relates to the field of obtaining a crystal of lithium triborate LiB₃O₅ (LBO), that is a highly efficient non-linear optical material used for passive frequency conversion of laser radiation. Method of growing a lithium triborate crystal involves loading the initial charge into a growth crucible, melting it and homogenizing it, bringing the point with the lowest temperature on the solution-melt surface to the center of the crucible, introduction of an oriented seed crystal in contact with the surface of the solution-melt in the center of the crucible, the search for an equilibrium temperature and the subsequent crystal growth with a decrease in temperature in the three-zone growth furnace, its middle and lower zones consist of eight heating elements, switching over time of which provides control of convective flows in the melt. Crystal is grown by lowering the temperature in the lower zone relative to the middle and upper zones, thus, so that at the end of the growth cycle, the temperature interval of lowering the lower zone increased by 5–10 %. At that in the first embodiment, the expansion is carried out with an increase in the process of increasing the shutdown time of 2, 3, 6 and 7 heating elements of the middle and lower zones, located along the crystallographic direction "b", from 5 to 7 seconds and from 20 to 23 seconds, respectively, while simultaneously decreasing the turn-off time of 1, 4, 5 and 8 heating elements of the middle and lower zones, located along the crystallographic direction "a", with 5 to 3 seconds and from 20 to 17 seconds, respectively. According to the second variant, the growth of the crystal is carried out when the shutdown time 5 and 8 of the heating elements of the lower zone changes from 30 to 35 seconds during the growth process, 6 and 7 from 30 to 37 seconds, 1 and 4 from 30 to 27 seconds and 2 and 3 from 30 to 23 seconds. According to the third variant, the growth of the crystal is carried out with an increase in the growth process of the turn-off time of 1, 8, 4 and 5 heating elements of the middle and lower zones, located along the crystallographic direction "a", from 6 to 11 seconds and from 30 to 37 seconds, respectively, and at the same time reducing the turn-off time 2, 3, 6 and 7 of the heating elements of the middle and lower zones, located along the crystallographic direction "b", from 6 to 1 second and from 30 to 23 seconds, respectively.

EFFECT: achieved technical result: the creation in the process of crystal growth dynamically changing, asymmetric thermal fields by controlling the heat flow in the melt from the heating elements of the growth furnace and obtaining LBO crystals of the required size in the specified crystallographic directions, providing the possibility of manufacturing nonlinear optical elements of increased size for various types of conversion of laser radiation.

3 cl, 11 dwg, 5 ex, 2 tbl