Influence of supersaturation on step evolution behavior of high concentration Fe3+ poisoned KDP crystal

Abstract

Abstract A series of potassium dihydrogen phosphate (KDP) crystals and Fe3+ doped KDP crystals were grown by “point seed” technique at different supersaturation. The prismatic faces growth rate of KDP crystals were measured by laser polarization interference system. The surface morphology of growth steps on {1 0 0} face were comparatively researched by atomic force microscope (AFM) systematically. The results showed that the crystal growth rate increased with the rise of supersaturation. It was interesting that the growth rate of KDP crystals in Fe3+ doped solution was faster than in un-doped solution when the supersaturation exceed 6.54%. The step bunching and slope both first increased then reduced and then rise, it shaped like “N”. The average step width of steps had a trend of first decreased then increased with the rise of supersaturation. The result of inductively coupled plasma (ICP) emission shown that the Fe3+ content increased with the rise of supersaturation. The X-ray diffraction (XRD) pattern suggested that the crystal structure had not changed after doping Fe3+.