Preparation and Properties of Low-Absorption Sapphire Crystal by Modified Kyropoulos Method.

In order to meet the demand for low-absorption sapphire crystal materials in important national defense projects in China, a self-produced crystal growth apparatus is developed in this study and the successful growth of low-absorption sapphire crystal can be achieved. The as-obtained crystal exhibits excellent transparency in the ultraviolet, visible, and near to midinfrared wavelength ranges. The transmittance is above 83% as the wavelength in the range of 250 nm to 400 nm, while the transmittance is above 85% as the wavelength in the range of 400 nm to 4 200 nm. On the basis of the characterization tests conducted on different regions of the crystal, the average dislocation density of crystal can be determined as 253. 19 cm-2. The rocking curve shows symmetrical and sharp peaks with a full width at half maximum of 14". In addition, it is worth noting that the light absorption coefficient of crystal is (23.3 -30.4) x 10-6 cm-1 at the wavelength of 1 064 nm, indicating that the impurity elements inside the crystal can be effectively controlled. Accordingly, the outstanding optical properties crystal can be applied in high-energy laser systems, space camera lenses and other relevant fields. [ABSTRACT FROM AUTHOR]