In Situ Intrinsic Self-Healing of Low Toxic Cs₂ZnX₄ (X = Cl, Br) Metal Halide Nanoparticles

This study reports on the intrinsic and fast self-healing ability of all inorganic, low-toxic Cs₂ZnX₄ (X = Cl, Br) metal halide nanoparticles (NPs) when subjected to local heating by electron beam irradiation in high-resolution transmission electron microscopy (HR-TEM). The local heating induces the creation of nanoshells (NSs) following the template of the corresponding NPs, which are subsequently healed back to their original state within several minutes. Energy dispersive spectroscopy (EDS) and fast Fourier transform (FFT) analysis reveal that the composition, phase, and crystallographic structure of the original NPs are restored during the self-healing process, with a thin crystalline layer observed at the bottom of the NSs acting as the healing template. The inelastic scattering of the electron beam energy generates local heat that causes rapid atomic displacement, resulting in atomic mobility that lowers the density of the material and leads to NS formation. A unique insitu TEM heating stage measurement demonstrates the appearance of identical damage and self-healing to those induced by the electron beam. The NPs exhibit excellent stability under ambient conditions for up to a month, making them suitable for self-healing scintillators and other optoelectronic applications that require atomic-scale stability and healing.