Selective Control of Oxidation Resistance of Diamond by Dopings.

Abstract

A method based on the density functional theory calculations is proposed for predicting the influences of dopants on the diamond oxidation, by evaluating the O adsorption energy, chemical bond weakening related to desorption, and probable products. It is proven by verification tests that oxidation resistances of the diamond materials can be indeed selectively controlled (e.g., -36 to 54.3% for diamond films, -36.5 to 45.1% for diamond grits) by adding various doping sources ((CH3O)3B, Si(OC2H5)4, N2, and CO(NH2)2), attributed to their direct impurity incorporation, or modified gas chemistry. B and Si dopings can improve the oxidation resistance, but the addition of N2 or urea plays an opposite role. Reactive ion etching and chemomechanical polishing tests are also accomplished, further demonstrating the influences of dopings on oxidation-related processes. This study paves the way for enhancing the efficiencies of the ultraprecision machining and micro-nano machining on the diamonds. Most importantly, the proposed prediction method can be potentially used in similar cases with other dopants and in other materials.