Giant dielectric permittivity of detonation-produced nanodiamond is caused by water

Abstract

We show that small (≤4%) amounts of water which detonation-produced nano-diamond powder always adsorbs spontaneously from air can increase its dielectric permittivity (ε) at low frequencies from single digits to over 10¹⁹, by far the highest value observed for any system including ferroelectrics. Conversely, traces of DND drastically affect the physical properties of water, increasing its ε from ∼80 to over 10⁶ and altering sound velocity. The effect is due to proton-releasing functional groups on the diamond surface interacting with the adsorbed water monolayer, hence it does not occur in hydrogen-free DND. The observed giant dielectric permittivity makes DND a prospective material for high-performance capacitors for use in microelectronics, and for the development of large-scale capacitance-based energy-storage devices urgently demanded in the quest for green energy technology. The results are also relevant for biomedical applications of DND and for understanding the enigmatic surface conductivity of diamond and electrical spectroscopy of porous rocks, which is important in geology.