Mitigation of subsurface damage in potassium dihydrogen phosphate (KDP) crystals with a novel abrasive-free jet process

Abstract

This study presents a novel abrasive-free jet process that can be used to mitigate the lattice misaligned structure induced by mechanical stresses in potassium dihydrogen phosphate (KDP) crystal subsurface. This method makes use of a thermodynamically and kinetically stable ionic liquid microemulsion that contains nanometer range water droplets evenly dispersed in the non-aqueous carrier liquid. The sprayed out nanoscale droplets remove material through microscale dissolution without introducing new residual stress. Grazing incidence X-ray diffraction was used to evaluate the subsurface structure and to validate the mitigating performance. The experimental results show that the novel mitigation method can effectively reduce the thickness of the deformed layer, as well as reduce the surface roughness. This approach ultimately provides a potential path to extend the lifetime of highly valuable and difficult to grow large KDP crystals.