BaY_2F_8 crystal growth and quality improvement

Title: BaY_2F_8 crystal growth and quality improvementAuthors: WEI Xiao-pingDegree-granting units: Tianjin UniversityKeywords: crystal growth;; temperature gradient;; crystal cracking;; ion polarizationSummary:

With the development of laser technology, laser crystal study more and more attention. BaY2F8 single crystal substrate as a fine crystal, because of its low refractive index, low voice and easy-to-energy ion doping sub-features are also highly concerned about the domestic and foreign researchers. Its different doping can produce different wavelengths of light, Neodymium magnets made of different applications of lasers. Pure BaY2F8 crystal growth process, the crystallization characteristics and physical properties of various rare earth or transition metal would doped BaY2F8 Preparation of single crystals have a good reference and guide, so the growth of single crystal is very pure BaY2F8 necessary, but also has practical significance. However, the preparation of single crystals at home and abroad on BaY2F8, mostly using Czochralski method, and the crystal size is not large, while the use of the temperature gradient may be prepared by a large single crystal. This selection of the temperature gradient method was successfully prepared single crystals of pure BaY2F8. Crystal diameter 10mm, length 40mm, good quality.

In this paper, theoretical analysis of bonding single crystal of pure BaY2F8 compared Er: BaY2F8 single crystal easy to crack reason. Er ions to form single crystals of Y ions into BaY2F8 position, which became a key part of the FY F-Er bond. As the ionic polarization of the reasons, F-Er bond stronger than the FY key, so that it can withstand greater thermal stress, and therefore the growth of macro-defect single crystal of pure BaY2F8, we need to grow Er: BaY2F8 based on single crystal improve the process.

Based on the repeated practice, this paper put forward the following to improve the crystal quality of the method:

1 small temperature gradient crystal growth.

Small temperature gradient, can reduce the thermal stress in the crystal, the crystal cracking and prevent cracks.

(2) selection of better quality, less volatile material made of graphite crucible.

Evaporation crucible serious http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php cause of graphite into the molten raw materials, and a crystal growth. However, due to the carbon atoms and all atoms in the crystal BaY2F8 the size difference is large, it will cause lattice distortion, the crystal quality. Use good quality materials to do the crucible, can effectively avoid this problem.

3 to improve the radial temperature field.

We obtained experimental radial temperature field is convex interface, it is easy for the growth of crystal bubbles and clouds, so we should try to make the radial temperature field level.Degree Year: 2010