Controlling Infrared Plasmon Resonances in Inverse-Spinel Cadmium Stannate Nanocrystals via Site-Selective Cation-Exchange Reactions

Abstract

Doped metal oxide nanocrystals (NCs) exhibit tunable localized surface plasmon resonances (LSPRs) in the infrared spectral region. Compared to the binary oxides commonly studied, plasmonic NCs derived from ternary oxides remain far less explored primarily due to the difficulty of controlling NC phase-purity and stoichiometry. Here, we report the synthesis of inverse spinel-type cadmium stannate (Cd2SnO4) NCs, for which cation-exchange reactions were developed to tailor their composition and LSPR properties. X-ray absorption spectroscopy studies revealed that the inequivalent tetrahedrally and octahedrally coordinated Cd2+ can be selectively exchanged for Cu+ and In3+ ions, respectively, enabling broadband tunable LSPR and Cu-mediated cation-exchange with lanthanide ions that are otherwise difficult to incorporate. Our work paves the way for systematic compositional engineering to accelerate the design of complex metal oxide NCs with emerging plasmonic, electronic, and magnetic properties.

Promoting 2D Material Photodetectors by Optical Antennas beyond Noble Metals

“…[ 154 ] As a consequence, non‐metal heteroatom‐doped semiconductor plasmonic nanostructures have garnered extensive research enthusiasm in recent years in the context of their advantage in large‐scale applications enabled by their competitive material cost. Thus far, a vast number of highly compelling doped semiconductor‐based plasmonic nanomaterials have emerged such as indium tin oxide (ITO), [ 155 ] STO, [ 154 ] Te‐doped Si, [ 78 ] H‐doped MoO 3 , [ 156 ] F and In co‐doped CdO, [ 157 ] Al‐doped ZnO, [ 158 ] H‐doped MoO 3 , [ 159 ] Ga 2 FeO 4 , [ 160 ] Cu/In‐doped Cd 2 SnO 4 , [ 161 ] and so on. Compared with classical metal optical antennas, semiconductor‐based optical antennas have exhibited distinct advantages.…”

Recent advances in nanostructured substrates for surface-enhanced infrared absorption spectroscopy

“…Currently, there are also some materials that are expected to become reliable SEIRA-active substrates by adjusting the LSPR frequency to the MIR region. For example, Zhong et al prepared cadmium stannate nanocrystals (Cd 2 SnO 4 NCs) with an inverse spinel-type crystal structure [189]. The composition of the nanomaterials and LSPR frequencies were transformed by introducing equivalent dopants by cation exchange reaction (selective exchange of Cd 2+ to Cu + and In 3+ ).…”

Observing Metallic Carriers in Highly Faceted Plasmonic Cd2SnO4 Inverse Spinel Nanocrystals

“…Not surprisingly, the development of plasmonic semiconductor nanocrystals (PSNCs) using wide bandgap (E g ), metal oxide (MO x ) semiconductors is beginning to replace noble nanometals for plasmonics research, reflecting their lower cost, high carrier densities (n >10 19 cm −3 ), transparency DOI: 10.1002/adom.202400388 in the visible spectral region, and the possession of a tunable localized surface plasmon resonance (LSPR) frequency. [7][8][9][10][11] MO x PSNCs are an important class of n-type plasmonic materials shown to exhibit high conductivity and mobility in thin films and form the basis of transparent conducting oxide industrial technology. [12][13][14][15][16][17] The LSPR frequencies of MO x PSNCs are predictable using dielectric modeling of the carrier effective mass (m * ), carrier density (n), band parabolicity, and degree of compensation centers arising from lattice defects.…”

“…CTO is nonmagnetic with carrier densities on the order of 10 19 -10 20 cm −3 and carrier effective masses ranging from 0.33 to 0.028m * /m e , depending on synthetic conditions. [7,[35][36][37][38][39][40] CTO has been of interest since the 1970s, following reports that thin film CTO is a potential transparent conducting oxide competitive with the well-known Sn:In 2 O 3 . [39][40][41] In thin film CTO, it was unclear whether the observed carriers were attributable to V O , typically observed in n-type MO x s, or antisite formation from the nonstoichiometric Sn to Cd ratio.…”