Study on the formation mechanism of asymmetric growth hillocks on pyramidal faces of KDP crystals

Abstract

The pyramidal face ({1 0 1} face) is one of the main growth faces of KDP crystals. The structure of growth hillocks grown on the pyramidal face has an important influence on the growth and properties of KDP crystals. Herein, the growth hillocks on the pyramidal faces of KDP crystals with rapid growth technology were investigated using an atomic force microscope (AFM). The results show that the morphology of growth hillocks on different pyramidal faces is related to crystal symmetry. The step orientation on vicinal sectors will have some deviation from the direction of theoretical PBC direction, which is caused by a kinked step. In order to explain the formation of asymmetric growth hillocks on the pyramidal faces of KDP crystals, facing steps on vicinal sectors are constructed. It was found that the difference in adsorption energy between the facing steps caused by the hydrogen bonds is the main reason for the formation of asymmetric growth hillock. On this basis, the corresponding relationship between the morphology of the growth hillocks grown on the pyramidal face of the KDP crystals and the face index was further clarified. Finally, the growth hillocks on the pyramidal face are divided into four types.