Research On The Raw Material Preparation And Growth Of DAST Crystals

THz technology was widely used in many areas,such as health care and military detection,because of its high penetrating and good security.Organic nonlinear optical crystal 4-di-methylamino-N-methyl-4-stilbazolium tosylate(DAST)was concerned in THz area due to its high nonlinear coefficient and electro-optic coefficient.In this paper,two methods for preparing DAST materials as THz radiation source were investigated.The products were investigated by elemental analysis,fourier transform infrared spectrum and nuclear magnetic resonance.The results demonstrated that the product was DAST.The diffraction peaks of the crystal planes were confirmed by XRD.High purity DAST materials for crystal growth were obtained by purification.The growth of DAST crystal was carried out and DAST crystals with dimention of 5×5×3mm~3 and 15×12×2mm~3 were grown by SNM method.The surface morphology of DAST crystal was observed by the microscope and the growth mechanism were described.The differences between DAST and DAST·H2O were also described in this paper.The mechanical,thermal and optical properties of DAST crystal were tested in this thesis.Vickers hardness of(001)face and(110)face was tested and the Meyer Index of DAST crystal was calculated.The melting point of DAST crystal was 258℃ by the TG and DTA analysis.The light transmission properties of DAST crystal was measured by optical transmittance spectra.The internal defects of DAST crystal was observed by synchrotron radiation topography and the reasons of defects were analyzed.