Structural Characterization of Colloidal Ag<sub>2</sub>Se Nanocrystals

Buschmann, V.; Tendeloo, G. Van; Monnoyer, Ph.; Nagy, J. B.

doi:10.1021/la9713210

Cited by 27 publications

(14 citation statements)

References 9 publications

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“…For small nanoprisms (~50 nm) expansion of the Ag 2 S tips is not observable under TEM (Figure 3A, M), consistent with a previous report, 45 which might be due to the instability of silver chalcogenides under the electron beam. 52 However, when we characterized the nanoprisms with AFM, both small (<100 nm) and large nanoparticles (~200 nm) showed a larger height profile at the tips indicating the Ag 2 S phase expansion (Figure 3G-L). parts for the small size (<100 nm) nanoprisms.…”

Section: Iii: High S X 2− Concentrationmentioning

confidence: 95%

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

et al. 2016

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Recently, Ag-Ag2S hybrid nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag-Ag2S nanostructures can be synthesized via sulfidation of as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties. In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag-Ag2S nanoprisms during the sulfidation of Ag precursors. The previously observed red-shifted extinction of the Ag-Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that sulfidation can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag-Ag2S nanoprisms, we find that, depending on the reaction conditions, sulfidation occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)-anisotropic shell(Ag2S) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2S at the prism tips and Ag2S shell thickness around the prism.

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Section: Iii: High S X 2− Concentrationmentioning

confidence: 95%

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

et al. 2016

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“…Ag 2 Se is a narrow‐band gap semiconductor that can exhibit phase‐dependent superionic Ag + conductivity and giant magnetoresistance [82–85] . In the bulk, Ag 2 Se crystallizes in a low‐symmetry orthorhombic phase up to ∼135 °C, whereupon it undergoes a first‐order phase transition to the superionic conducting body‐centered cubic phase [86–88] . However, for nanocrystals, a third phase of Ag 2 Se with tetragonal lattice parameters is also known to form at relatively low temperatures [14–16,89,90] .…”

Section: Syntheses Of Colloidal Semiconductor Nanocrystals With Metasmentioning

confidence: 99%

“…Thermodynamically, the cubic phase of Ag 2 Se is stable above T >135 °C [86–88] . However, this superionic conducting phase can be kinetically trapped at lower temperatures, and has even been observed at room temperature [138] .…”

Section: Properties and Applications Of Semiconductor Nanocrystals Wimentioning

confidence: 99%

Polymorphic Metastability in Colloidal Semiconductor Nanocrystals

Tappan

Brutchey

2020

ChemNanoMat

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Metastable polymorphs of inorganic solids often possess material properties not present in the corresponding thermodynamic polymorphs, making them targets for the development of new functional materials. In contrast with isolating metastable bulk materials, syntheses of metastable polymorphs on the nanoscale are aided by fast non‐equilibrium reaction kinetics and the favorable thermodynamic influence of surface energies, giving rise to greater ease of access to metastable high‐temperature polymorphs and, in some cases, new polymorphs that do not exist in the bulk. The syntheses of metastable semiconductor nanocrystals are of interest for their potentially unique optoelectronic and physicochemical properties. However, in many material systems, synthesizing nanocrystalline products away from thermodynamic equilibrium in a predictable manner remains an outstanding challenge. This review outlines direct synthetic methodologies that have been developed to enable control over the nucleation and growth of metastable polymorphs of semiconductor nanocrystals by tailoring reaction conditions, precursor kinetics, ligand and surface effects, and other synthetic levers. The case studies reviewed herein expound on the direct syntheses of metastable ZnSe, Cu2SnSe3, CuInSe2, Ag2Se, and AgInSe2 nanocrystals, and although there remain numerous examples of metastable nanocrystal syntheses outside of these metal chalcogenide systems, the concepts discussed are of general utility to the field of metastable nanocrystal syntheses as a whole. Explicit examples in which new functional properties are afforded by metastable polymorphs of the aforementioned material systems are presented within the context of applications for solar cells, photonics, and optical sensing. Finally, the factors that affect the kinetic persistence of metastable nanocrystalline polymorphs are discussed at length for these material systems.

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“…In this context, a variety of synthesis methods have been developed to prepare nanocrystalline silver selenide (Ag 2 Se) because this promising A I 2 B VI semiconductor can be used to make solar cells, 8 magnetic field sensors, 9 solidstate electrochemical sensors, 10 and optical filters. 11 Prevalent synthesis methods include the use of microwave radiation, 12 sonochemical force, 13 microemulsion mixing, 14 and electrochemical potential 15 to drive the decomposition of selenium and/ or silver compounds to form Ag 2 Se. To promote the growth of specific, desirable nanocrystalline morphology, various molecular precursors, additives, and surfactants are introduced.…”

Section: Introductionmentioning

confidence: 99%

Using Elemental Se and Ag to Grow Pure Ag₂Se Dendrites/Dendritic-Films of Highly Oriented (001) Nanocrystals

Zheng

Shui

et al. 2008

J. Phys. Chem. C

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A clean, facile route of using only common bulk selenium (Se) powder and silver (Ag) foil in a simple solvothermal process is developed to synthesize a film of silver selenide (Ag 2 Se) dendrites of highly oriented (001) nanocrystals. The simple process takes ∼10 h at 160°C in a common alcohol such as methanol or ethanol in an autoclave, and the reaction time is shorter than in many prevalent methods. The adoption of elemental Se and Ag (foil) in the synthesis eases the control of the purity of the product, simplifies the reaction steps, and reduces the costs, as the synthesis does not require Se and Ag compounds, and also requires no chemical additives other than an alcohol as solvent. The results support a mechanism of dissolution of the bulk-like Se powder in the solvothermal process, transport of solvated Se to react with Ag, nucleation of Ag 2 Se nanocrystals, surface-mediated, solvation-assisted surface diffusion of Ag 2 Se nanocrystals, and diffusionlimited aggregation of the Ag 2 Se nanocrystals through oriented attachment for the growth of dendrites having highly oriented (001) nanocrystals. The clean, relative facile route is practical for the fabrication of Ag 2 Se crystals/films with hierarchically ordered nanostructures for future applications in solar cell devices. More importantly, the same concept can be adopted for the synthesis of other nanomaterials with bulk elemental reactants with no reliance on chemical compounds or additives.

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Structural Characterization of Colloidal Ag₂Se Nanocrystals

Cited by 27 publications

References 9 publications

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Polymorphic Metastability in Colloidal Semiconductor Nanocrystals

Using Elemental Se and Ag to Grow Pure Ag₂Se Dendrites/Dendritic-Films of Highly Oriented (001) Nanocrystals

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Structural Characterization of Colloidal Ag2Se Nanocrystals

Cited by 27 publications

References 9 publications

Ag–Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Ag–Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Polymorphic Metastability in Colloidal Semiconductor Nanocrystals

Using Elemental Se and Ag to Grow Pure Ag2Se Dendrites/Dendritic-Films of Highly Oriented (001) Nanocrystals

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Structural Characterization of Colloidal Ag₂Se Nanocrystals

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Ag–Ag₂S Hybrid Nanoprisms: Structural versus Plasmonic Evolution

Using Elemental Se and Ag to Grow Pure Ag₂Se Dendrites/Dendritic-Films of Highly Oriented (001) Nanocrystals