Formation of gaseous cavity defect during growth of Nd:YAG single crystals

In this research, formation of gaseous cavity defect in 1 at%Nd:YAG single crystal grown by the Czochralski technique has been studied. Growth atmosphere pressure and crystal rotation rate were optimized in order to prevent the defect formation. The microstructure of the defect was characterized using scanning electron microscopy (SEM) and wavelength dispersive spectroscopy (WDS) analyses. The stresses induced by the gaseous cavity were also investigated by parallel plane polariscope. The results show that the growth atmosphere pressure has a more significant influence on defect formation compared to the crystal rotation rate. In addition, decreasing the growth atmosphere pressure leads to growth of the crystals with no gaseous cavity defect. The results also show that Nd concentration varies around the defect making these areas useless for solid-state lasers application.

► Formation of gaseous cavity defect in Nd:YAG single crystal was investigated.
► Growth atmosphere pressure is an important parameter for avoiding cavity formation.
► Changing of rotation rate is not effective in preventing cavity formation.
► Beside the defect area, large areas around this defect have low optical quality.
► Fluctuation of Nd concentration occurs in the vicinity of the defect.