Quantum-confined GaN nanoparticles synthesized via liquid-ammonia-in-oil-microemulsions

Gyger, Fabian; Bockstaller, Pascal; Gröger, Henriette; Gerthsen, D.; Feldmann, Claus

doi:10.1039/c4cc00180j

Cited by 14 publications

(28 citation statements)

References 23 publications

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“…[104] Moreover,MEs using ionic liquids as the polar droplet phase have been described recently. [104,107] Their potential and current limitations are discussed in the following. As an additional restriction, the presence of small amounts of water cannot very often be excluded.…”

Section: Hydrogen Peroxide and Liquid Ammonia Based Microemulsionsmentioning

confidence: 99%

Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles

Wolf

Feldmann

2016

Angew Chem Int Ed

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Microemulsions (MEs) are ideal for obtaining high-quality inorganic nanoparticles. As thermodynamically stable systems with a nanometer-sized droplet phase that serves as a nanoreactor, MEs have obvious advantages for the synthesis of nanoparticles. MEs also have disadvantages, such as their complexity as multicomponent systems, the low amount of obtainable nanoparticles, their limited thermal stability, the fact that hydrolyzable or oxidizable compounds are often excluded from synthesis, the partly elaborate separation of nanoparticles, as well as the removal of surface-adhered surfactants subsequent to synthesis. This Review presents some strategies to further expand the options of ME-based synthesis of inorganic nanoparticles. This comprises the crystallization of nanoparticles in "high-temperature MEs", the synthesis of hollow nanospheres, the use of hydrogen peroxide or liquid ammonia as the polar droplet phase, and the synthesis of base metals and nitrides in MEs.

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Section: Hydrogen Peroxide and Liquid Ammonia Based Microemulsionsmentioning

confidence: 99%

Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles

Wolf

Feldmann

2016

Angew Chem Int Ed

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“…The large blue shift on the PL emission implies strong quantum confinement effects in GaN-NCs due to ultrasmall NCs generation (i.e., smaller than the doubled exciton Bohr radius for GaN (Ramvall et al 1998) using fs PLA (Miyamura et al 2002;Mazumder and Hector 2008). Gyger et al (2014) observed blue shift of 1.1 eV in PL spectra of 3-4 nm size GaN-NCs compared to band gap energy of bulk GaN. When GaN crystals become clusters, there are several effects which may change the band gap according to some theoretical studies and calculations (Brus 1986;Kayanuma 1988;Yoffe 2002;Dimos et al 2012).…”

Section: Resultsmentioning

confidence: 99%

“…Development of GaN-based blue light emission devices (e.g., light-emitting diodes and laser diodes) (Nakamura et al 1991(Nakamura et al , 1996Denbaars 1997) accelerated the research on GaN. By limiting the size of a material to smaller than the doubled exciton Bohr radius, the material starts showing novel optical and structural properties like blue shift in optical absorption and PL spectra in comparison with the band gap emission of bulk material (Ramvall et al 1998;Gyger et al 2014). Crystalline GaN quantum dots provide enhanced carrier confinement-induced blue shift (Leppert et al 1998;Mićić et al 1999;Klimov et al 2000;Preschilla et al 2000;Miyamura et al 2002) and allow one to design core-shell nanostructures (Reiss et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Hexagonal nanocrystalline GaN with the size of 2-3 nm was generated by Borsella et al (2001) via sequential Ga and N ions implantation into crystalline and amorphous dielectrics tracked by annealing of the samples GaN in flowing ammonia gas at 900°C. Recently, quantum-confined cubic GaN nanoparticles with the size of 3-4 nm have been synthesized by Gyger et al (2014) via liquid-ammonia-in-oil-microemulsions. Laser ablation method is also a promising technique to generate a wide variety of metal and semiconductor nanoparticles (Yang 2012;Alkis et al 2012;Zeng et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…A number of nanocrystalline GaN studies were reported through some grown techniques (Mićić et al 1999;Borsella et al 2001;Miyamura et al 2002;Zhuang et al 2013;Gyger et al 2014). GaN quantum dots were grown by Miyamura et al (2002) through low-pressure metalorganic chemical vapor deposition.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

et al. 2016

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We demonstrate the synthesis of GaN nanocrystals (NCs) with the sizes of less than the doubled exciton Bohr radius leading quantum confinement effects via a single-step technique. The generation of colloidal GaN nanoparticles (NPs) in organic solution through nanosecond (ns) and femtosecond (fs) pulsed laser ablation (PLA) of GaN powder was carried out. Ns PLA in ethanol and polymer matrix resulted in amorphous GaN-NPs with the size distribution of 12.4 ± 7.0 and 6.4 ± 2.3 nm, respectively, whereas fs PLA in ethanol produced colloidal GaN-NCs with spherical shape within 4.2 ± 1.9 nm particle size distribution. XRD and selected area electron diffraction analysis of the product via fs PLA revealed that GaN-NCs are in wurtzite structure. Moreover, X-ray photoelectron spectroscopy measurements also confirm the presence of GaN nanomaterials. The colloidal GaN-NCs solution exhibits strong blue shift in the absorption spectrum compared to that of the GaN-NPs via ns PLA in ethanol. Furthermore, the photoluminescence emission behavior of fs PLA-generated GaN-NCs in the 295-400 nm wavelength range is observed with a peak position located at 305 nm showing a strong blue shift with respect to the bulk GaN.

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Mikroemulsionen: neue Möglichkeiten zur Erweiterung der Synthese anorganischer Nanopartikel

Wolf

Feldmann

2016

Angewandte Chemie

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Mikroemulsionen (ME) sind ideal, um hochwertige anorganische Nanopartikel zu erhalten. Als thermodynamisch stabile Systeme mit einer Phase aus Nanometer‐großen Tröpfchen, die als Nanoreaktoren dienen, bieten sie für die Nanopartikelsynthese eine Reihe an Vorteilen. ME haben aber auch Nachteile, z. B. ihre Komplexität als Mehrkomponentensysteme, die geringe erhältliche Nanopartikelmenge, die begrenzte thermische Stabilität, der häufige Ausschluss hydrolysierbarer oder oxidierbarer Verbindungen von der Synthese, die partiell sehr aufwendige Abtrennung der Nanopartikel sowie die Entfernung Oberflächen‐gebundener Tenside nach der Synthese. Dieser Aufsatz soll einige Strategien zur Erweiterung der ME‐basierten Synthese anorganischer Nanopartikel aufzeigen. Dazu zählen die Kristallisation von Nanopartikeln mittels “Hochtemperatur‐ME”, die Synthese nanoskaliger Hohlkugeln, die Verwendung von H2O2 oder flüssigem NH3 als polare Tröpfchenphasen sowie die Synthese von unedlen Metallen und Nitriden in ME.

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Quantum-confined GaN nanoparticles synthesized via liquid-ammonia-in-oil-microemulsions

Cited by 14 publications

References 23 publications

Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles

Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles

Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

Mikroemulsionen: neue Möglichkeiten zur Erweiterung der Synthese anorganischer Nanopartikel

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