Formation of new growth spirals due to impact with a rod on the (010) face of KAP

Abstract

We performed contacting experiments on the (010) face of potassium hydrogen phthalate (KAP) crystals, using an advanced in situ microscopic technique. This allowed us to observe directly the impact and the effects on the crystal surface induced by the impact. Some seconds to minutes after most collisions, new growth spirals appeared in the vicinity of the contacted area. The number of new growth spirals varied and turned out to be independent of contact energy covered by our experiments, the severeness of the damage and the surface structure. The origin of the new growth spirals can be twofold: (a) inactive screw dislocations are activated, (b) new (active) screw dislocations are formed. The formation of new growth spirals could also be a combination of these two processes.