The Effect Of EDTMPA On The Growth And Property Of KDP Crystal

Potassium dihydrogen phosphate（KH₂PO₄,KDP）crystal is an excellent nonlinear optical crystal.It has many nonlinear optical effects and is widely used in industry.Therefore,how to grow large-scale and high-quality KDP crystals quickly has become a popular focus.According to previous studies,it is known that impurities in the growth solution is one of the reasons that affect the growth and properties of KDP crystal.Therefore,in this article,EDTMPA（ethylenediamine tetramethylene phosphonic acid）,a kind of organic complexing agent,is doped in the solution to reduce a kind of impurity ions,aiming to reduce or eliminate the influence of such impurity ions on the growth and properties of KDP crystal.The effect of different doping concentration on the growth and properties of KDP crystal was analyzed.The specific research contents and conclusions are as follows:（1）The pure KDP crystal and KDP crystals grown from solutions with 200 ppm,400 ppm,600 ppm and 800 ppm EDTMPA doped were obtained by the method of point seed rapid growth technique.It is found that the growth rate in the pyramidal faces and prismatic face are both changed.（2）Through powder X-ray diffraction（XRD）experiment,it is found that the characteristic peaks of the XRD patterns of the crystals grown from doped solutions are the same as those of the pure crystal,and there are no other characteristic peaks,in addition,the peak positions do not change,which indicate that EDTMPA additives have no effect on the single crystal structure of KDP crystal and no other crystal phase is generated.（3）Through FT-IR test,it is found that the absorption peaks of KDP crystals grown from EDTMPA doped solutions are the same as that of pure KDP crystal with no other absorption peak,which indicates that the EDTMPA additives do not enter into the KDP crystal.（4）According to the UV-vis-NIR transmission spectrum,EDTMPA additives have little effect on the optical parameters of KDP crystal in the visible and NIR region,but it will change the optical parameters of KDP crystal in the UV region:when the doping concentration is low,the UV transmittance of the crystal is decreased,the refractive index,extinction coefficient,optical conductivity and electrical conductivity are improved;with the high the EDTMPA concentrations,the UV transmittance of the crystal is arisen,and the refractive index,extinction coefficient,optical conductivity and electrical conductivity are decreased.（5）According to the TG-DSC curve of KDP crystals,EDTMPA additives have no obvious effect on the initial reaction temperature and endothermic peak of KDP crystal,and the weight loss of KDP crystals grown from solutions containing EDTMPA are decreased.（6）The dislocation density of crystals with 200 ppm and 400 ppm additives are higher than that of pure KDP crystal,while the dislocation density of crystals with 600ppm and 800 ppm additives are lower than that of pure KDP crystal.（7）From the single pulse irradiation damage experiment,it is shown that the laser damage threshold of KDP crystals grown from solutions containing EDTMPA are decreased.