Device for adjusting radial thermal gradient in crucible of crystal-growing furnace

The invention relates to a device for adjusting radial thermal gradient in a crucible of a crystal-growing furnace, which comprises a platinum reflecting cover and a fireproof insulating cover, wherein the platinum reflecting cover is covered on the upper end of the crucible and is provided with a first central through hole; the fireproof insulating cover is covered on the upper surface of the platinum reflecting cover and is provided with a second central through hole; the diameter of the first central through hole is 1/9-5/9 of the inner diameter of the crucible; the diameter of the second central through hole is 2-5mm larger than the diameter of the first central through hole; and the upper surface of the fireproof insulating cover (3) is a plane surface. The invention has the advantages that the platinum reflecting cover of the device can play a role of a reflecting screen, can effectively adjust the radial thermal gradient in the crucible in the crystal-growing furnace and simultaneously also can play a role of reducing volatilization of the components, the grown crystals have no defects of scattering particles, inclusion, growth stripes and the like, and the utilization ratio of the crystals is greatly improved. The device of the invention is suitable for the growth of various functional crystals of BBO, CBO, KTP and the like, especially the growth of CBO crystals.