| Zdroj: |
Ward-O'Brien, B, Mcnaughter, P, Cai, R, Chattopadhyay, A, Flitcroft, J, Smith, C, Binks, D, Skelton, J, Haigh, S & Lewis, D 2022, ' Quantum Confined High Entropy Lanthanide Oxysulfide Colloidal Nanocrystals ', Nano Letters, pp. 8045–8051 . https://doi.org/10.1021/acs.nanolett.2c01596 |
| Popis: |
We have synthesized the first reported example of quantum confined high entropy (HE) nanoparticles, using the lanthanide oxysulfide, Ln2SO2, system as the host phase for a equimolar mixture of Pr, Nd, Gd, Dy and Er. A uniform HE phase was achieved via the simultaneous thermolysis of a mixture of lanthanide dithiocarbamate precursors in solution. This was confirmed by powder X-ray diffraction and high-resolution scanning transmission electron microscopy, with energy dispersive X-ray spectroscopic mapping confirming the uniform distribution of the lanthanides throughout the particles. The nanoparticle dispersion displayed a significant blue shift in the absorption and photoluminescence spectra relative to our previously reported bulk sample with the same composition, with an absorption edge at 330 nm and a λmax at 410 nm compared to the absorption edge at 500 nm and a λmax at 450 nm in the bulk, which is indicative of quantum confinement. We support this postulate with experimental and theoretical analysis of the band gap energy as a function of strain and surface effects (ligand binding) and calculation of the Bohr exciton radius for the end member compounds. |
