Anisotropy etching of synthetic diamond single crystals by Pr6O11 powder

Abstract

The work aims to explore the anisotropic etching of synthetic diamond single crystal by rare earth oxide. Under the protection of nitrogen, synthetic diamond single crystals were etched by Pr6O11 powder at 750-950℃. The surface morphology, phase composition and etching mechanism of different crystal surfaces of diamond single crystal after etching were characterized and analyzed by means of scanning electron microscopy, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy, and the changes of diamond properties before and after etching were characterized by surface roughness, single particle compressive strength and impact toughness. The results show that the etching degree and morphology of {100} faces and {111} faces of diamond by Pr6O11 are different. When the temperature is 750℃, Pr6O11 etches slightly diamond crystals. The etching intensifies with the increase of etching temperature, moreover the etching degree of diamond {111} faces is more serious than that of {100} faces. The morphologies of the etching pits of diamond {111} faces change from triangular etching pits to layered triangular ones, and {100} faces change from slight quadrilateral to honeycomb-like etching pits. The maximum etching depth of {100} face increases from 1.12 μm to 12.54 μm, while the maximum etching depth of {111} face increases from 0.3 μm to 2.11 mm. The compressive strength of single diamond particle decreases from 576.25 N of unetched diamond to the smallest value of 530.06 N, and the impact toughness decreases from 92.94 J/cm2to 88.53 J/cm2. The etching mechanism of diamond single crystal by Pr6O11 is catalytic graphitization before 885℃, and the catalytic graphitization and oxidation after 885℃.

Keywords

• diamond single crystal
• pr6o11
• anisotropic etching
• etching mechanism
• property