Defects and impurities in colloidal Ga<sub>2</sub>O<sub>3</sub> nanocrystals: new opportunities for photonics and lighting

Nguyen, Khue Vu; Radovanovic, Pavle V.

doi:10.1139/cjc-2021-0203

Cited by 5 publications

(1 citation statement)

References 89 publications

(114 reference statements)

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“…5 nm, which is consistent with other samples synthesized by similar methods. ,, The Fe-rich (Ga/Fe = 1.4) and Ga-rich (Ga/Fe = 2.4) GFO NCs have very similar XRD patterns (Figure b), which are in excellent agreement with that for bulk Ga 2 FeO 4 having an inverse spinel crystal structure (vertical lines in Figure b). In the ideal structure and stoichiometry, oxygen ions form a cubic close-packed lattice in which all Fe 2+ and one half of the Ga 3+ cations occupy octahedral (O h ) sites, while the other half of the Ga 3+ cations occupy tetrahedral (T d ) sites . At room temperature, some Fe 2+ ions could also occupy T d sites due to cross-substitution of the Fe 2+ and Ga 3+ (T d ) cations .…”

Section: Results and Discussionmentioning

confidence: 99%

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

et al. 2023

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Plasmonic semiconductor nanocrystals (NCs) have emerged as an attractive alternative to noble metal nanoparticles. They typically exhibit localized surface plasmon resonance (LSPR) in the infrared range, which can be tuned by controlling the type and concentration of charge carriers. Compositionally and electronically complex semiconductor NCs have attracted significant attention due to their reported plasmonic properties, such as bipolar behavior (off-stoichiometric spinel-type gallium iron oxide or GFO), wide tunability (copper iron chalcogenide or Cu x Fe y S2–z Se z ), and extremely broad LSPR (oxygen-deficient WO3–x ). However, the origin of these unusual properties remains unclear. Here, we comparatively investigate the plasmonic properties of these semiconductor NC materials using magnetic circular dichroism (MCD) spectroscopy, owing to the highly specific response of LSPR to the magnetic field and light polarization. In all systems, we find indisputable evidence that the LSPR absorption bands have been mischaracterized. MCD signals that coincide with the absorption bands previously assigned to LSPR of GFO and Cu x Fe y S2–z Se z NCs show rapid saturation with the magnetic field and independence on the sign of charge carriers, indicating that the corresponding absorption bands are not due to LSPR. This behavior is consistent with intra-ionic and inter-band transitions for GFO and Cu x Fe y S2–z Se z NCs, respectively. The MCD signal corresponding to the absorption spectrum of WO3–x NCs shows Brillouin function dependence on the magnetic field at high photon energies (attributed to d–d transitions of W5+) and linear dependence in the near-infrared range (attributed to LSPR), indicating that the broad absorption spectrum of WO3–x NCs is only partly associated with LSPR. The results of this work help resolve notable discrepancies in the literature, underline the challenges in assigning absorption bands of complex semiconductor NCs to LSPR, and demonstrate that MCD spectroscopy is an invaluable tool for characterization of these materials.

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Section: Results and Discussionmentioning

confidence: 99%

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

et al. 2023

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Preface to the special section in memory of Professor Kenneth F. O'Driscoll

Cunningham

Soares

2021

Can J Chem Eng

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We are honoured to dedicate this special section of The Canadian Journal of Chemical Engineering to the memory of Professor Kenneth Francis O'Driscoll, a beloved mentor, friend, and outstanding scientist who passed away on 4 August 2020 in Kitchener,Ontario. The overwhelmingly enthusiastic response we had from former students and colleagues to the invitation to contribute to this special section is testimony to the many lives Ken touched during his career. This special section features 12 invited papers from researchers around the world, reflecting the extent and depth of Ken's scientific legacy in polymer science and engineering. [1][2][3][4][5][6][7][8][9][10][11][12] Ken was born 22 July 1931 in Staten Island, New York City. He attended the prestigious Regis High School in Manhattan and then the Pratt Institute for his BChE (1952). He moved to Princeton University for his graduate studies under the supervision of Arthur V. Tobolsky in the Department of Chemistry (MA 1957, PhD 1958. Following his doctoral studies, Ken accepted his first academic position in Chemical Engineering at Villanova University (1958-1966) and then SUNY Buffalo (1966-1970 before moving to the University of Waterloo (1970Waterloo ( -1992, where he served as Professor and Department Chair. He was the Founding Director of the Institute for Polymer Research at the University of Waterloo. In 1996, Ken was named Distinguished Professor Emeritus.Ken published over 200 research papers on a wide range of topics in polymer science, including polymer reactor engineering (with Alex Penlidis, he co-founded the journal Polymer Reaction Engineering, which has become Macromolecular Reaction Engineering), hydrogels (he developed the hydrophilic contact lens, better known as the soft contact lens), and

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A facile route to synthesize β‐Ga₂O₃ nanoparticles from γ‐polymorph through a rapid microwave route and their optical properties

Nazir,

Masood,

Shivashankar

et al. 2024

Vietnam Journal of Chemistry

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Due to the wide bandgap, monoclinic structure and thermodynamic stability, β‐polymorph form of Ga2O3 nanomaterials is well‐received for various applications. However, as the γ‐Ga2O3 is difficult to synthesize, less attention has been paid towards it and its conversion to β‐polymorph. This paper reports the single‐step synthesis of γ‐Ga2O3 using a microwave‐assisted procedure. In this regard, γ‐Ga2O3 powders are synthesized in minutes using benzyl alcohol as the solvent using gallium acetylacetone as the precursor. The XRD of the as‐prepared powders indicates the formation of the γ‐Ga2O3 phase, the very broad peaks indicative of the small crystallite size as confirmed by TEM. The γ‐Ga2O3 powders were annealed at different temperatures and the complete phase conversion of γ‐Ga2O3 phase to β‐Ga2O3 phase happens at 700 °C. The TEM analysis shows the crystallite size to be ≈10 nm for the annealed β‐Ga2O3 phase. The as‐prepared nanopowders show very weak luminescence under excitation and in contrast, a blue‐green emission is observed in case of annealed powders. This confirms the presented strategy as having the potential to use β‐Ga2O3 nanopowders for different optoelectronic applications.

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Defects and impurities in colloidal Ga₂O₃ nanocrystals: new opportunities for photonics and lighting

Cited by 5 publications

References 89 publications

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

Preface to the special section in memory of Professor Kenneth F. O'Driscoll

A facile route to synthesize β‐Ga₂O₃ nanoparticles from γ‐polymorph through a rapid microwave route and their optical properties

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Defects and impurities in colloidal Ga2O3 nanocrystals: new opportunities for photonics and lighting

Cited by 5 publications

References 89 publications

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

Revisiting Plasmonic Properties of Complex Semiconductor Nanocrystals Using Magnetic Circular Dichroism Spectroscopy: A Cautionary Tale

Preface to the special section in memory of Professor Kenneth F. O'Driscoll

A facile route to synthesize β‐Ga2O3 nanoparticles from γ‐polymorph through a rapid microwave route and their optical properties

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Defects and impurities in colloidal Ga₂O₃ nanocrystals: new opportunities for photonics and lighting

A facile route to synthesize β‐Ga₂O₃ nanoparticles from γ‐polymorph through a rapid microwave route and their optical properties