Interaction between diamond surface and molten alkali metals

Abstract

It has not been studied what interaction exists between diamond surfaces and molten alkali metals. We encapsulated diamond single crystals with alkali metals (Li, Na, K) with Ar gas in Nb tubes and heated. We found that etching with Li happens from 600°C and (001) surface is etched most. We further studied the electronic interaction by measuring the fluorescence of NV^- centers. Only K induced the decrease of the fluorescence intensity. With the aid of DFT calculation, it is concluded band bending to the upper side is responsible.