Excited carrier dynamics of α-Cr2O3/α-Fe2O3 core-shell nanostructures

In this work alpha-Cr2O3/R-Fe2O3 core-shell polycrystalline nanostructures were synthesized by using R-Cr2O3 nanoparticles as seed crystals during aqueous nucleation. The formation of alpha-Fe2O3 polycrystallites on R-Cr2O3 surfaces was confirmed by X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray analysis. The excited-state relaxation dynamics of as-grown core-shell structures and pure R-Fe2O3 particles of the same size were measured with femtosecond transient absorption spectroscopy. The results show the carrier lifetimes decay within a few picoseconds regardless of sample. This is likely due to fast recombination/ trapping of carriers to defects and iron d-states.