Enhancement of growth rate for BSO crystals by improving thermal conditions

Effects of various thermal conditions on growth of single crystal of Bi12SiO20 (BSO) with a floating zone method were systematically investigated. The following are the main results: (1) Change of heating source from an infrared heater to a CO2-laser system could have increased the temperature gradient in the grown crystal near the solid-liquid interface about 3 to 4 times, which gives rise to a dramatic increase of the critical transparent growth rate more than 3 times. (2) A single crystal seed with high thermal conductivity (e.g., Al2O3) can dramatically increase the critical transparent growth rates. (3) For a source rod of the multi-sintered powder rod, an increase of growth rate from 18.8 mm/h to 100 mm/h can decrease the diameter fluctuation of the grown crystal from 2~3%/cm to less than 0.5%/cm.