Study On The Growth And Properties Of DKDP Crystals With Low Oeuterated Lervel

Inertial Confinement Fusion(ICF)is a kind of heat nuclear explosion that can be controlled in the laboratory,which will be one of the most promising methods for generating environmentally safe energy in the future.In the long term,the ICF has a practical applied prospect in overcoming the shortage of energy of human Bing,which attracts the attention of the world.The important optical element of high power laser in ICF is the frequency conversion crystal.The requirement of laser frequency conversion crystal is large size,with high laser damage threshold.Although so far a large number of the new type linear optical crystal constantly emerge,only the potassium dihydrogen phosphate(KH2P04,KDP)and the potassium dihydrogen phosphate deuterium(K(H1-XDX)2PO4,DKDP)kind of crystal can satisfy the requirement of ICF engineering of crystal materials throughout the existing nonlinear nonlinear optical materials.The return wavelength of 12-DKDP crystal is located at the band of 1.05?m,which can support the high efficiency double frequency of the 1.05 m laser with the bandwidth greater than 20nm(10mm of crystal light length).At present,the growth and properties of KDP and DKDP was investigated widely in the world,but those studies are rarely conducted in the K(H1-XDX)2PO4 with low deuterium content.Thereforein this work,we systematically study on the structure,spectra,optical properties and high-temperature transition of K(H 1-XDX)2PO4 with low deuterated level.The main contents of this paper are as follows:1.Refractive indices of K(H1-XDX)2PO4 crystals,in which the range of x was from 0.1 to 0.18,was measured in the visible region by vertical incidence method.The results showed that the refractive index and birefringence decreased with the increasing of deuterium content in K(H1-XDX)2PO4 crystals.A linear equation and a Sellmeier equation were used to match the refractive index of K(H1-XDX)2PO4 crystal with deuterium content and wavelength respectively,permitting the interpolation with experimental data.Refractive indices of deuterated KDP crystal with arbitrary at varying wavelength can be can be calculated by the fitting formula,providing a way to calculating the nonlinear optical coefficient of the K(H1-XDX)2PO4 crystals such as phase matching angle.2.The effect of the deuterium content on the crystal spectra of K(H1-XDX)2PO4 were studied by using transmission spectrum,the infrared spectrum and Raman spectrum.The transmission efficiency of the infrared band increase with the increase of the deuterium content,no absorption are observed in all crystals,at 355nm in the UV region,there are some absorption which are not sensitive to the deuterium content.With the increase of the deuterium content in crystal,the infrared cutoff of crystal is redshifted.At the same time,this reveal that the hydrogen modes and the deuterium modes are essentially independent with each other.The infrared absorption peaks of the infrared absorption peak and the O-H/D key of the crystal are gradually moving towards the high wave segment with the increase of the deuterium content in the crystal,and the relation between the crystal deuterium content and the vibration peak displacement is obtained by linear fitting.Two Raman peaks,arise mainly from internal vibration modes of the po4 clusters in K(H1-XDX)2PO4.The red-shift of the vibration mode occurs with the increase of deuterium content in the K(H1-XDX)2PO4 crystal,which is linear dependent on the deuterium content of the crystal.3.Optical properties of K(H1-XDX)2PO4 were measured by laser damage threshold.The test results show that the optical quality of K(H1-XDX)2PO4 crystal decreases with the increase of deuterium content in the range of 10%to 20%.After annealing,the laser damage threshold of the crystals are 1.3?1.4 times of the damage threshold of the crystals which did not anneal.It is proved that annealing treatment is a efficient way to improve damage resistance.There is little difference in the increase of the laser damage threshold with the different deuterium content crystal after annealing treatment.4.Measurement of heating treatment,differential thermal analysis and thermogravimetric analysis(DTA-TG),dielectric constant and infrared spectrum were used to study high temperature transition in K(H1-XDX)2PO4 crystals.The result of TG demonstrate that the onset of thermal decompositions at 482K-487k,at the same time,the result of DTA shows that the starting point of the endothermic phenomenon of K(H1-XDX)2PO4 crystals was lower 3?5K than the temperature which crystals began to Weightlessness.Heating treatment shows the high-temperature transition point of K(H1-XDX)2PO4(x=0.1,0.12,0.14,0.16,0.18)are about at 441K,446K,451K,464k,469K which the crystal change from transparent to opaque.Measurements of dielectric constants shows the existence of two kinds of phase transitions Tp and Tl,the Tp is dependent on a change in hydrogen/deuterium bond,and this temperature drops with the increase of deuterium content of the crystals.By measuring the infrared spectrum of the crystal,the results shows infrared spectrum of 10%DKDP crystal after 469k heating are basically as same as the infrared spectrum measured in room temperature,and after heating with 487k two new characteristic peak appear in the crystal infrared spectrum.