Selective Control of Oxidation Resistance of Diamond by Dopings.

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 ((CHO)B, Si(OCH), N, and CO(NH)), attributed to their direct impurity incorporation, or modified gas chemistry. B and Si dopings can improve the oxidation resistance, but the addition of N 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.