2.2.11 Noble metals

Mehrer, H.; Stolica, N.; Stolwijk, N. A.

doi:10.1007/10390457_20

Cited by 8 publications

(3 citation statements)

References 27 publications

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“…D 0 is the pre-exponential factor, and E is the activation energy as appearing in refs and . Based on the literature values, the diffusion coefficients of Sn and Cd at 180 °C in the NCs studied were calculated to be ∼3.4 × 10 2 and ∼8.2 × 10 3 nm 2 s –1 , respectively.…”

mentioning

confidence: 99%

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Jang

Yanover

Capek

et al. 2016

J. Phys. Chem. Lett.

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Controlling the synthesis of narrow band gap semiconductor nanocrystals (NCs) with a high-quality surface is of prime importance for scientific and technological interests. This Letter presents facile solution-phase syntheses of SnTe NCs and their corresponding core/shell heterostructures. Here, we synthesized monodisperse and highly crystalline SnTe NCs by employing an inexpensive, nontoxic precursor, SnCl2, the reactivity of which was enhanced by adding a reducing agent, 1,2-hexadecanediol. Moreover, we developed a synthesis procedure for the formation of SnTe-based core/shell NCs by combining the cation exchange and the Kirkendall effect. The cation exchange of Sn(2+) by Cd(2+) at the surface allowed primarily the formation of SnTe/CdTe core/shell NCs. Further continuation of the reaction promoted an intensive diffusion of the Cd(2+) ions, which via the Kirkendall effect led to the formation of the inverted CdTe/SnTe core/shell NCs.

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mentioning

confidence: 99%

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Jang

Yanover

Capek

et al. 2016

J. Phys. Chem. Lett.

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“…The diffusion coefficient ( D ) and diffusion length ( L ) at two reaction temperatures (i.e., 50 and 140 °C) were estimated by employing the Arrhenius equation (eq ) and the root-mean-square distance (eq ), respectively. − The diffusion coefficient and length values are given in Table . D 0 , E , k , T , and t are the pre-exponential factor, activation energy, Boltzmann constant, temperature, and time, respectively. Self-diffusion constants ( D 0 and E ) were adopted from ref and are supplied in Table S1 in the Supporting Information. Since these values are typically reported in the literature at high temperature ranges, extrapolation was performed for the working temperatures in the present case …”

Section: Resultsmentioning

confidence: 99%

Kirkendall Effect: Main Growth Mechanism for a New SnTe/PbTe/SnO₂ Nano-Heterostructure

et al. 2018

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Attention to semiconductor nanostructures with a narrow band gap energy and low production cost has increased in recent years, due to practical demands for use in various optoelectronics and communication devices. Colloidal nanostructures from the IV–VI semiconductors, such as lead and tin chalcogenides, seem to be the most suitable materials platform; however, their poor chemical and spectral stability has impeded practical applications. The present work explored the mechanism for formation of new nanostructures, SnTe/PbTe/SnO2, with a core/shell/shell heterostructure architecture. The preparation involved a single-step post-treatment for the preprepared SnTe cores, which simultaneously generated two different consecutive shells. The process followed a remarkable Kirkendall effect, where Sn ions diffused to the exterior surface from a region below the surface and left a ringlike vacancy area. Then Pb ions diffused inward and created a PbTe shell, filling the Sn-deficient region. Finally, the ejected Sn ions at the exterior surface underwent oxidation and formed a disordered SnO2 layer. These intriguing processes were corroborated by a theoretical estimation of the relative diffusion length of the individual elements at the reaction temperature. The nanostructures which were comprised of low-toxicity elements were endowed with optical tunability and chemical stability, which lasted more than one month at ambient conditions.

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“…The formation process was further corroborated by a theoretical calculation, employing a diffusion coefficient ( D ) and diffusion distance ( L ). Those values can be estimated by using an Arrhenius relation (eq ) and the root-mean-square distance (eq ), respectively: − …”

Section: Kirkendall Effectmentioning

confidence: 99%

Recent Advances in Colloidal IV–VI Core/Shell Heterostructured Nanocrystals

et al. 2018

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Colloidal nanocrystals (NCs) have been at the forefront of scientific research and technological applications since their emergence in the 1980s. The limitations of single component NCs and the growing demand for wide electronic tunability switched the attention to core/shell nanoheterostructures (NHs). The NHs consist of at least two semiconductor compounds, exhibiting improved surface passivation of the cores and surplus electronic tunability beyond that gained by size confinement. Several synthetic approaches have been developed through the years for the formation of core/shell structures. This article discusses two recent synthetic approaches, cation exchange and the Kirkendall effect, for the preparation of core/shell NHs, focusing on IV–VI semiconductor compounds. Both cation exchange and the Kirkendall effect are postsynthetic routes which offer an indirect way to synthesize complex core/shell NHs, that are difficult to synthesize by other methods. Overall, the produced core/shell NCs show enhanced optical properties and improved chemical sustainability with respect to the corresponding pure cores.

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2.2.11 Noble metals

Cited by 8 publications

References 27 publications

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Kirkendall Effect: Main Growth Mechanism for a New SnTe/PbTe/SnO₂ Nano-Heterostructure

Recent Advances in Colloidal IV–VI Core/Shell Heterostructured Nanocrystals

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2.2.11 Noble metals

Cited by 8 publications

References 27 publications

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Kirkendall Effect: Main Growth Mechanism for a New SnTe/PbTe/SnO2 Nano-Heterostructure

Recent Advances in Colloidal IV–VI Core/Shell Heterostructured Nanocrystals

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Kirkendall Effect: Main Growth Mechanism for a New SnTe/PbTe/SnO₂ Nano-Heterostructure