Strain annealing of SiC nanoparticles revealed through Bragg coherent diffraction imaging for quantum technologies

The crystalline strain properties of nanoparticles have broad implications in a number of emerging fields, including quantum and biological sensing in which heterogeneous internal strain fields are detrimental to performance. Here we used synchrotron-based Bragg coherent x-ray diffraction imaging (BCDI) to measure three-dimensional lattice strain fields within individual 3C-SiC nanoparticles, a candidate host material for quantum sensing, as a function of temperature during and after annealing up to ${900}^{\phantom{\rule{0.16em}{0ex}}\ensuremath{\circ}}\mathrm{C}$. We observed pronounced homogenization of the initial strain field at temperatures above ${500}^{\phantom{\rule{0.16em}{0ex}}\ensuremath{\circ}}\mathrm{C}$, and we find that the surface layers and central volumes of the nanoparticles reduce strain at similar rates, suggesting a uniform healing mechanism. Thus, we attribute the observed strain homogenization to activation of mobile point defects that annihilate and improve the overall quality of the crystal lattice. This work also establishes the feasibility of performing BCDI at high temperatures (up to ${900}^{\phantom{\rule{0.16em}{0ex}}\ensuremath{\circ}}\mathrm{C}$) to map structural hystereses relevant to the processing of quantum nanomaterials.