添加剂EDTA对KDP晶体快速生长的影响研究

Influence of EDTA additive on rapid growth of KDP crystal

在添加不同浓度（0～5×10-3）EDTA 的KDP饱和溶液中,采用“点籽晶”快速生长技术生长了KDP晶体,生长速度约20 mm/d.研究了不同浓度的EDTA对KDP晶体快速生长的影响.实验发现,随着溶液中EDTA添加量的增加,KDP 晶体（100）面的生长速度是先增加经过一个最大值然后减小；晶体宏观外形高宽比则是先减小经过一个最小值然后增加.在溶液中添加适量浓度的EDTA（5×10-5～5×10-4）可以有效地提高生长溶液的稳定性；而过量的添加 ED-TA（＞1×10-3）反而会破坏溶液的稳定性,当溶液中EDTA浓度增至5×10-3时,溶液甚至发生“雪崩”,晶体出现母液包藏、添晶和粉碎性裂纹等缺陷.结合KDP的晶体结构和EDTA的分子特点,对其影响机理进行了讨论.

KDP crystals were grown from aqueous solutions,added with different concentrations of EDTA （0-5×10-3 ）,by “point seed”rapid growth technique.The growth rates up to about 20 mm/d.Effects of different concentrations of EDTA-additive on the rapid growth of KDP crystal were investigated.It was found that,with increasing the concentration of EDTA in solution,the growth rate for （100）face of KDP crystal firstly in-creased and then decreased,passing through a maximum;while the aspect ratio of macroscopic shape of these as-grown crystals firstly decreased and then increased,passing through a minimum.Appropriate amount of ED-TA （5×10-5-5×10-4）doped in growth solution enhanced the stability of growth solution,but excess addition of EDTA （〉1 × 1 0-3 ）had the adverse effect.When the concentration of EDTA in solution increased to 5 × 10-3 ,“avalanche”even occurred in solution and many macro defects of crystal appeared,such as mother liquid inclusions,parasite crystals and crushing cracks.The impact mechanism was also analyzed combining with the structure of KDP crystal and chemical characteristic of EDTA molecule.