Plasmon Responses in the Sodium Tungsten Bronzes

Tegg, Levi; Cuskelly, Dylan; Keast, V. J.

doi:10.1007/s11468-017-0528-y

Cited by 29 publications

(37 citation statements)

References 58 publications

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“…The other peak at ω ≈ 6.5 eV arises from the interband transition in the UV, as seen in figure 5. EELS have been measured experimentally on these materials, and has been presented in previous work from this research group [69] and from others [66,70]. In brief, excellent qualitative agreement has been observed between calculated and observed EELS, particularly in the visible frequency range.…”

Section: Electronic Structure and Optical Propertiesmentioning

confidence: 52%

“…With reference to figure 5, it can be seen that an increase in the band gap for any given stoichiometry is unlikely to reduce the quality of any plasmon resonance, though it may slightly increase the frequency. As discussed, EELS has been performed on the samples fabricated in this work, and it was shown that there is strong agreement between calculation and experiment, especially in the frequencies of bulk and surface plasmons [69]. This suggests that although the bandgap has been underestimated, these calculations are sufficiently accurate to describe the free-electron contribution to the optical properties.…”

Section: Electronic Structure and Optical Propertiesmentioning

confidence: 54%

“…It is the free-electron character of the bronzes which leads to the broad spectrum of colours observed in the sodium tungsten bronze series [68]. increases with increasing Na content, approximately following ωBP √x  √N [69]. The x = 0.000 curve, corresponding to WO3, does not have a bulk plasmon peak, which is expected given its semiconductor character.…”

Section: Electronic Structure and Optical Propertiesmentioning

confidence: 96%

See 2 more Smart Citations

The sodium tungsten bronzes as plasmonic materials: fabrication, calculation and characterization

Tegg

Cuskelly

Keast

2017

Mater. Res. Express

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The tungsten bronzes are non-stoichiometric transition metal oxides of the form MxWO3, where 0 ≤ x ≤ 1, and M is a dopant ion, most commonly an alkali metal. In this work, the sodium tungsten bronzes (NaxWO3) are investigated as materials for plasmonic applications. The bronzes were fabricated with a solid state reaction, the dielectric function calculated using density functional theory (DFT) and the nanoparticle responses calculated with the boundary element method (BEM). The results were compared to Au and Ag, the materials most widely used in plasmonic applications. It was shown that for x > 0.5, the solid state fabrication method produces cube-shaped particles of diameter ≥ 1 μm, whose bulk optical properties are well described by a free-electron model and a rigid band structure. The addition of Na into the lattice increases the free electron density, increasing the bulk plasma frequency. Nanoparticle plasmon resonances are found to be highly tunable, and generally at a lower frequency than Au or Ag, and so sodium tungsten bronzes are predicted to be well suited to biomedical or chemical sensing applications.

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Section: Electronic Structure and Optical Propertiesmentioning

confidence: 52%

Section: Electronic Structure and Optical Propertiesmentioning

confidence: 54%

Section: Electronic Structure and Optical Propertiesmentioning

confidence: 96%

See 1 more Smart Citation

The sodium tungsten bronzes as plasmonic materials: fabrication, calculation and characterization

Tegg

Cuskelly

Keast

2017

Mater. Res. Express

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“…For example, a figure‐of‐merit based on the real part of the resistivity correctly indicates that this material is inferior to Au and slightly inferior to ZrN for applications in metamaterial structures, whereas an examination of ε 2 would indicate the opposite . The alkali tungsten oxides, named the tungsten bronzes due to their yellow and metallic luster, are low‐cost, corrosion resistant metallic oxides with low values of ε 2 in the visible region, making them an attractive proposition for plasmonic applications . Other conductive oxides should also be considered.…”

Section: Compounds Between Metals and Nonmetalsmentioning

confidence: 99%

The Quest for Zero Loss: Unconventional Materials for Plasmonics

2019

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There has been an ongoing quest to optimize the materials used to build plasmonic devices: first the elements were investigated, then alloys and intermetallic compounds, later semiconductors were considered, and, most recently, there has been interest in using more exotic materials such as topological insulators and conducting oxides. The quality of the plasmon resonances in these materials is closely correlated with their structure and properties. In general gold and silver are the most commonly specified materials for these applications but they do have weaknesses. Here, it is shown how, in specific circumstances, the selection of certain other materials might be more useful. Candidate alternatives include TixN, VO2, Al, Cu, Al‐doped ZnO, and Cu–Al alloys. The relative merits of these choices and the many pitfalls and subtle problems that arise are discussed, and a frank perspective on the field is provided.

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“…The origin of the strong NIR absorption in reduced tungsten oxides and tungsten bronze nanoparticles has been attributed to localized surface plasmon resonance (LSPR) of free electrons and polaronic excitation of trapped electrons. [6][7][8][9][10][11][12][13][14][15][16] In Cs-doped HTB (Cs-HTB), recent analyses indicate that W-5d orbitals in the lower conduction band are occupied by the free and trapped electrons originating from Cs + and oxygen vacancies (V O ), respectively. 17,18,40 The V O s have been analyzed to play a major role in the LSPR and polaronic excitation.…”

Section: Introductionmentioning

confidence: 99%