Size and nitrogen inhomogeneity in detonation and laser synthesized primary nanodiamond particles revealed via salt-assisted deaggregation

Detonation nanodiamonds (DND), their properties and deaggregation remain an active field of research. Here we innovated the salt-assisted ultrasonic deaggregation (SAUD) by employing NaHCO3 (a milling agent with relatively low solubility) followed by dialysis (a purification step) and processed two DND and one laser-synthesized (LND) commercial powders. The obtained ND colloids were separated to single-digit supernatant with the yield of 57–65% and sediment fractions by centrifugation and analyzed separately. By thermal analysis we evidenced chemical sensitization of the SAUD-processed DNDs manifested by significantly lower combustion temperatures. By correlation of spectroscopic, microscopic, and thermal analysis techniques we revealed a size and shape inhomogeneity of primary DND particles, also affecting strength of aggregation. By elemental analysis of the fractions we also show that nitrogen content is systematically higher in the smaller primary DND particles. Those features are inherent to all the three ND samples. The provided analyses highlight the need for better understanding of relations between detonation synthesis parameters and properties of the synthesized DNDs in terms of DND primary particle size, aggregation and nitrogen incorporation. [Display omitted] •Size, shape and nitrogen inhomogeneity in detonation nanodiamond revealed by salt-assisted ultrasonic deaggregation (SAUD).•Smaller primary DND particles (4-5 nm) have higher nitrogen content, are less faceted, and are released by SAUD.•Larger primary DND particles (> 10 nm) have lower nitrogen content, are well faceted and, remain aggregated after SAUD.•Facets-driven electrostatic interactions and the liquid-phase sintering are both involved during DND synthesis.•The results evidence a compositional and kinetic inhomogeneity in the reaction zone during detonation synthesis.