六偏磷酸盐对KDP晶体快速生长及光学性能的影响研究

Effects of hexametaphosphate on rapid growth and optical properties of KDP crystals

在掺杂不同浓度的六偏磷酸盐溶液中,利用"点籽晶"快速生长法生长了KDP晶体,生长速度约20 mm/d。研究了六偏磷酸盐对快速生长的KDP晶体的生长及光学性能的影响,并与传统慢速生长的晶体进行了对比。实验表明,溶液中掺杂少量六偏磷酸盐就会显著降低生长溶液的稳定性,抑制晶体的生长,生长的晶体容易出现包藏、添晶、粉碎性裂纹等缺陷;生长的晶体光学质量也明显下降,例如晶体内部的光散射加重,激光损伤阈值降低;相比传统生长法生长的晶体,同等浓度的六偏磷酸盐对"点籽晶"快速生长法生长的晶体影响更为严重。结合KDP的晶体结构和六偏磷酸盐的分子特点,对其影响机理进行了讨论。

By altering the concentration of hexametaphosphate in the growth solution,a series of KDP crystals were grown by “point seed”rapid growth method at the growth rates about 20 mm/d.Effects of hexametaphos-phate on the rapid growth and optical properties of these as-grown KDP crystals were investigated,comparing with those crystals grown by the traditional temperature lowering method.The results indicated that,the sta-bility of growth solution was decreased greatly and the growth of crystal faces was inhibited significantly in the presence of a small amount of hexametaphosphate.At the same time,many macro defects occurred easily such as mother liquid inclusions,parasite crystals and crushing cracks.Furthermore,due to the presence of hexamet-aphosphate,the light scattering in KDP crystals was aggravated markedly and the laser damage threshold was decreased greatly.The crystal grown by “point seed”rapid growth was affected more severely than that by tra-ditional growth method,in the same concentration of hexametaphosphate.The impact mechanism was also ana-lyzed combining with the structure of KDP crystals and chemical characteristics of hexametaphosphate mole-cules.