Spinel Plasmonic Metal Oxide Nanocrystals, The Role of Antisite Occupation and Faceting on the Observed Plasmon Properties

Plasmonic metals have been a rich area of research for over two decades, exhibiting shape and size dependent extinction spectra. In n-doped wide band gap metal oxide semiconductors, a plasmon feature (w_p) is observed due to the introduction of carriers. In these plasmonic semiconducotr nanocrystals (PSNC), the plasmon frequency and spectral shape are correlated with the number of free carriers (n) at the Fermi level, the carrier effective mass (m*), and the faceting of the metal oxide nanocrystal. The stability of the free carrier in these materials is impacted by the nature of the surface passivation. Solid state NMR, high field EPR , and optical techniques allow the free carrier to be probed, the carrier mass measured, and the impact of faceting and surface interfaces to be evaluated. In the presentation, the role of surface, shape, faceting magneto-optical and synthetic approaches to address fundamental questions in classical oxygen vaccancy PSNCs WO_3-x , and spinel antisite PSNCs CdSn₂O₄ will be explored.