Abstract: The formation mechanism of main defects in TeO2 single crystals grown by Czochralski technique and the effects of growth parameters on defects have been studied in this paper.The results showed that the cracking in TeO2 single crystal is mainly related to the temperature gradient.To avoid the crystal being cracked and to decrease the dislocation density,the crystal can be grown under temperature gradient of 20-25℃/cm.And the incorporation of gas inclusions into the crystal is due to the pulling rate and the seed rotation rate.The crystal without bubbles can be obtained when a rotation rate of 15-18r/min and a pulling rate of 0.55mm/h are employed,which can lead a concave solid-liquid interface.The reason for growth steps in crystal can be explained by the instability of temperature and growth speed during growth process.

Key words: The formation mechanism of main defects in TeO2 single crystals grown by Czochralski technique and the effects of growth parameters on defects have been studied in this paper.The results showed that the cracking in TeO2 single crystal is mainly related to the temperature gradient.To avoid the crystal being cracked and to decrease the dislocation density,the crystal can be grown under temperature gradient of 20-25℃/cm.And the incorporation of gas inclusions into the crystal is due to the pulling rate and the seed rotation rate.The crystal without bubbles can be obtained when a rotation rate of 15-18r/min and a pulling rate of 0.55mm/h are employed,which can lead a concave solid-liquid interface.The reason for growth steps in crystal can be explained by the instability of temperature and growth speed during growth process.