Photothermal effects during nanodiamond synthesis from a carbon aerogel in a laser-heated diamond anvil cell

Abstract

Nanodiamonds have emerged as promising materials for quantum computing, biolabeling, and sensing due to their ability to host color centers with remarkable photostability and long spincoherence times at room temperature. Recently, a bottom-up, high-pressure, high-temperature (HPHT) approach was demonstrated for growing nanodiamonds with color centers from amorphous carbon precursors in a laser-heated diamond anvil cell (LH-DAC) that was supported by a near-hydrostatic noble gas pressure medium. However, a detailed understanding of the photothermal heating and its effect on diamond growth, including the phase conversion conditions and the temperature-dependence of color center formation, has not been reported. In this work, we measure blackbody radiation during LH-DAC synthesis of nanodiamond from carbon aerogel to examine these temperature-dependent effects. Blackbody temperature measurements suggest that nanodiamond growth can occur at 16.3 GPa and 1800 K. We use Mie theory and analytical heat transport to develop a predictive photothermal heating model. This model demonstrates that melting the noble gas pressure medium during laser heating decreases the local thermal conductivity to drive a high spatial resolution of phase conversion to diamond. Finally, we observe a temperature-dependent formation of nitrogen vacancy centers and interpret this phenomenon in the context of HPHT carbon vacancy diffusion using CBΩ theory.

High-pressure, high-temperature molecular doping of nanodiamond

“…Unlike ion implantation, which requires annealing to drive vacancy diffusion to activate incorporated heteroatoms, optically active color centers form immediately upon HPHT conversion to diamond. Theoretical and experimental results show that, at these pressures, subnanometer sp 3 carbon grains nucleate at each aerogel grain’s core and diamond growth with simultaneous Ostwald ripening continues radially ( 15 , 41 , 42 ). The production of homogeneously distributed defects suggests that, as the diamond lattice forms around the heteroatomic silicon and nitrogen atoms, the lowest-energy color center structure forms immediately.…”

Facile diamond synthesis from lower diamondoids

“…The results also elucidate the basic properties and mechanistic pathways that affect the facile (hydro)carbon-to-diamond conversion, including the diamond-like structures and bonding, as well as quaternary carbon atoms that enable a swift conversion. The facile synthesis of diamond suggests a promising use of diamondoids for investigating light-emitting defects in diamonds, which is of interest in the fields ranging from quantum technologies to biological sciences (30)(31)(32). Doped or functionalized with targeted defect elements, these energy-and time-efficient precursors can lead to better understanding and discovery of color center-containing diamonds.…”

Quantum Point Defects for Solid‐State Laser Refrigeration

“…Recently it has been demonstrated that color centers can be introduced within diamond materials using a wide range of molecular precursors including silicic acid (SiOH 4 ), [ 165,199 ] tetraethylorthosilicate (Si(OCH 2 CH 3 ) 4 ), [ 138 ] and also a mixture of naphthalene (C 10 H 8 ) with tetrakis(trimethylsilyl)silane (C 12 H 36 Si 5 ). [ 200 ] A range of different HPHT techniques may be used including a laser‐heated diamond anvil‐cell (DAC), [ 138,165,199 ] a multi‐anvil press , [ 201 ] a toroid press, [ 200 ] and more recently a resistively‐heated DAC followed by ion‐irradiation and thermal annealing. [ 202 ] HPHT techniques have also been demonstrated to incorporate noble‐gas point defects within nanodiamond materials.…”