Changes in the functional chemical compositions of surface and structural defects of diamonds, due to the nonthermal influence of nanosecond high voltage pulses

Abstract

Fourier transform infrared spectroscopy (FTIR), analytical electron and atomic force microscopy, and physicochemical examination of the structure and properties of mineral surfaces are used to study changes in the structural defects, functional and chemical compositions, and surface electrical properties and hydrophobicity of diamond surfaces exposed to nonthermal nanosecond high-voltage pulse treatment. The degradation of secondary mineral phase films, their peeling from the diamond surfaces, the growth of crystal hydrophobicity, and an increase in the number of B2 defects were observed after 50 s of treatment with electric pulses. Lengthening the period of irradiation (the dose) to 150 s resulted in oxidation of the diamond surfaces by products of water–air medium radiolytic decomposition, which led to the production of hydroxyl and/or carbonyl groups on the crystal surfaces, a further shift of the diamond electrokinetic and electrostatic potential into the region of negative values, and deterioration of the diamond’s hydrophobic properties.