The Ph Value Of Kdp Crystal Growth

KH₂PO₄ (abbr.KDP)crystal is a kind of non-linear optical material with excellentperformance. It is easy to be grown larger than other crystals. KDP crystals areusually grown by temperature cooling method in solution under condition ofcomparatively low temperature. So the growth process and morphology of crystals areeasy to be observed. At the same time, it also provides a good model for crystalgrowth study. On the basis of doing crystal growth experiment, our work can besummarized as follows:1) The conception and theoretic calculation about metastable zone and inductionperiod of KDP crystals solution were introduced. On the base, solubility and solutionstability experiments were carried out. The solubility curves of KDP were measuredwith different pH values. Metastable zone and induction period of KDP crystal werealso measured. The experiment results were explained by the theory of solutionstability.2) The ideal shape of KDP crystal was decided by the direction and distribution ofchemical bonds in KDP crystal. The influence of different growth condition andimpurity on growth habit was also relevant to these. In this thesis, the influence of pHvalue on KDP crystal habits was discussed by carrying out KDP growth experimentsin solutions with different pH values. Without adding any additives to growth solution,three-dimension growth of KDP crystal was realized by modifying the pH value ofsolution. The influence of acetic acid on KDP crystallization habits was analyzed bycomparing KDP crystallization morphology in acetic acid and in ethanol solution,respectively.3) Chemical etching method was chosen to study the dislocation of KDP crystal.The distribution characteristics and density of dislocation etching pits were observedand analyzed by the optical microscopy. It was found that most etching pits lined, pHvalue had great influence on dislocation density of KDP crystal. The samples of KDPcrystals grown from the solution with low pH value had more dislocation density. Thetransmittance of KDP crystals taken from different parts of samples was tested. Theresult showed that there was no direct correlation between dislocation density andKDP crystal transmittance.