Development Of Micro-pulling-down Equipment And Crystal Growth

Micro-pulling-down method is a novel crystal growth technology. This method has the following characteristics:The usage of materials is very few in each time thus greatly reduced the cost of new materials exploration, reduced costs of exploration of new materials; It need less crucible materials, for example small size of platinum and iridium crucibles; Fiber diameter from micron to millimeter scale is adjustable and the interface of optical fiber crystal is controllable; GGG, LuAG, YAG and other oxide crystals can be grown at high temperature. As the technology is relatively new developed, the commercialization of the equipment has not reached large-scale production level. Therefore, most of the international research institutes used self-made or cooperatively developed micro pulling down equipment to do research on crystal growth. Based on directional solidification principle, for the low temperature oxide crystal growth characteristics, micro pulling down equipment has been successfully designed and developed in cooperation with the business, and the equipment has been applied to the crystal growth on oxide fibers.BGO (Bi4Ge3O12) and BSO (Bi4Si3O12) crystals are two important scintillators. BGO is a well konwn oxide scintillation crystal which has the advantages of colorless, transparent, can prevent radiation ability, high scintillation efficiency, strong anti-radiation ability and hard to deliquescence, etc.It is a comprehensive performance excellent scintillation materials. BSO is also a kind of scintillation crystal with the characteristics of fast decay and high intensity of radiation. Considering BGO and BSO has the same crystal structure and close melting point, it is expected that the mixture of BGO and BSO may result in novel scintillation crystals, that is Bi4(Ge1-xSix)3O12 (BGSO) mixed crystals. BGSO fiber crystals with x=0,0.05,0.10 and 0.15 have been grown in the furnace. The growth parameters were optimized and BGSO up to 195mm in length was obtained. The XRD patterns and emission spectra have measured and the results showed that the lattice parameter decrease linearly with the increase of Si contents while the main emission peak move to short wave with the increase of Si contents.