Observing Metallic Carriers in Highly Faceted Plasmonic Cd2SnO4 Inverse Spinel Nanocrystals

Correlating data from optical, structural, and theoretical methods allows the properties of highly faceted Cd2SnO4 (CTO) inverted spinel plasmonic semiconductor nanocrystals (PSNCs) to be fully evaluated. The use of Sn(II) in the colloidal reaction for CTO results in reproducible octahedral PSNCs with an aspect ratio of 1.30. Correlating extinction spectra with magnetic circular dichroism yields a carrier density (n = 5.19 × 1019 cm−3) and carrier effective mass (m* = 0.022me) respectively. 113Cd and 119Sn solid‐state NMR experiments show clear evidence of metallic‐like carriers in CTO NCs based upon the observation of Knight shifts. These data suggest that carrier formation in CTO arises from Sn antisite occupation of octahedral Cd sites (SnCd). From a broader perspective, the results point to wide‐bandgap spinels as being an important but understudied class of plasmonic PSNCs. Metallic behavior is observed for carriers in highly faceted, octahedron‐shaped Cd2SnO4 (CTO) plasmonic semiconductor nanocrystals. The carriers in CTO arise from antisite occupation (SnCd). Consistent with metallic character, a short wavelength infrared plasmon, strong 113Cd and 119Sn NMR Knight shift, and a carrier effective mass of 0.022me is observed.