Growth of high quality nonlinear optical crystal 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST)

We have grown organic nonlinear optical 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystals by using slow cooling method. X-ray diffraction (XRD) indicates the dependence of the crystallinity of DAST crystal to the growth conditions with the best rocking curve as narrow as 15.8 arcsec full width at half-maximum (FWHM). Although X-ray projection topography indicates the existence of growth striations and planar defects along the direction of a-axis. This crystal is in fact excellent in quality for an organic crystal. Vickers hardness as high as 49 was obtained and is found to increase with the decrease of the FWHM of XRD rocking curve.