The Study On Growth And Characterization Of High Quality DKDP Crystal By Point Seed

The grown solution of DKDP crystal was synthesized firstly, then the relationship between concentrations of metal ion impurities and critical supersaturation was discussed by the measurement of metal ion impurity concentrations. By studing the relationship of overheating temperature, overheating time and solution stability, the result shows overheating can decrease the number of molecule cluster and the probability of nucleation in the solution. The growth solution was adjacent to the most stability in virtue of the overheating time beyond 20 hours and overheating temperature beyond 15*C of the saturation temperature of DKDP crystal growth solution. The research of Gibbs free energy, critical nucleus radius, nucleation rate of homogeneous nucleation' and heterogeneous nucleation shows that the main reason decreasing solution stability is heterogeneous nucleation.Some DKDP single crystals have been grown by temperature falling method on the Z-cut point seed (5mmX 5mmX 3mm) in DKDP metastable crystal phase district. The high quality DKDP crystal growth conditions of the falling temperature speed of 0. 5-3癈/day, the growth temperature range of 48-23 癈 and the pD=4.0-4. 2 have been achieved in glass crystallizer of 250ml in volume, the growth rates reach to 3mm/day in both the [100] and [001] directions. The DKDP crystal with dimensions of 34'mmX 36mmX 45mm and weight of 99g was successfully grown with the growth rate of 4. 5 mm/day in glass crystallizer of 1000ml in volume. The growth mechanism of DKDP crystal was described by the formation, diffusion and adsorption of growth unit of DKDP crystal. The method of increasing the growth rate was discussed. The reason of the formations of monoclinic crystals and inclusion in growth system was discussed in detail, then the method of the prevention to form monoclinic crystals and inclusion was putforward.The UV-VIS transmission spectra and concentrations of metal ion impurities in different part of DKDP crystal was measured. The results show concentrations of metal ion impurities on the (100) face is higher than that on the (110) face and absorption on the (100) face is bigger than that on the (110) face. By analyzing the difference on (lOO)and (110) face in the structure of DKDP crystal, the different of UV-VIS transmission spectra and the different of concentrations of metal impurities in different part of DKDP crystal was explained.The results of property test of DKDP crystal grown on a point seed show that laser damage threshold is about 5GW/cm2 ,?half-wave voltage is about 4Kv, extinction ratio is about 1600: l.The obvious difference of DKDP crystals is not found between traditional technique and point seed growth technique. The point seed growth techniques of high quality DKDP crystal in all directions have these features of fast growth rate, high utilization ratio and low growth cost.