Study On The Solution Stability And The Nucleation Characteristic Of L-Arginine Doped ZTS Crystals

Zinc tris(thiourea) sulphate （Zn[CS(NH2)2]3SO4）single crystal, one kind oforganic-metal coordination compound, as a new non-linear optical material（sNLO）hashigh optical non-linearity, high laser damage threshold, low angular sensitivity and wideoptical transparency in the entire visible. So ZTS crystal can be widely used intype-Ⅱ secondary harmonic generation and frequency conversion of high-power lasers.In addition, ZTS crystal has some other significant advantages, for example, the lowprices of raw material, stable physicochemical properties, high mechanical strength andso on. With more and more researches on ZTS crystals, there will be higher applicationprospects.Though the growth of ZTS crystal has been undertaken by many researchers, theemphasis focus on the crystals growth and performance analysis in different growthconditions, including kinds of organic and inorganic additives, influence of solution pHand so on. ZTS crystals can be grown from aqueous sulution, so the effect of solutionenvironment on the crystal growth process and crystal queality is obvious. However,there is little detailed investigation on the sulution stability and the thermodynamic andkinetic of ZTS. So the experiments of the solution stability, crystals growth and qualitydetecting, doped with different molar concentration of L-arginine, were carried out inthis thesis. The nucleation parameters for pure and L-arginine mixed ZTS solution at30℃, which are essential for optimizing the growth parameters in order to grow bulkcrystals, has been estimated. The effect of L-arginine on the ZTS crystals quality hasbeen presented through the dislocation etching pits and the IR spectrum, which alsocombined with the solution stability. The main works can be summarized as follows:①The raw materials were synthesized from zinc sulfate and thiourea.②The solubility of ZTS in water were measured, and the solubility curves aregiven. The measurements were made from25℃to40℃in steps5℃or less.Yet thesolubility and solubility-temperature coefficient in water was relatively low, so it hadbetter to grow ZTS crystal by combining method of slow-cooling and vaporing.③The metastable zone width and induction period of ZTS solution doped withdifferent molar concentration of L-arginine were presented. It is found the metastablezone width and induction period of ZTS solution increased with the increase of dopingconcentration, which enhanced the solution stability. ④Based on the classical nucleation theory, the thermodynamic and kineticparameters of nucleation were calculated from the induction period data. The resultsshow that there is a significant variation in the interfacial tension, critical free energy ofnucleus, number of molecules in the critical nucleus and radius of critical nucleus due tothe increase of L-arginine in ZTS solution.⑤The dislocation etching pits on the (100) plane of growth ZTS crystals wereevaluated by dislocation etching and optical microscopy technique. The results indicatethat lower dislocation density can be achieved at concentration of1.5mol%L-arginine,so can get the high quality ZTS crystal at a optimized condition.⑥The incorporation of L-arginine into ZTS crystal was confirmed by fouriertransformed infrared spectra(FT-IR) study.