Energy Gap Evaluation in Microcrystalline m-HfO2 Powder

Shilov, A. O.; Savchenko, S. S.; Вохминцев, А. С.; Чукин, А. В.; Карабаналов, М. С.; Vlasov, Maksim; Weinstein, I. A.

doi:10.17516/1997-1397-2021-14-2-226-231

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…The authors claim that the indirect bandgap in amorphous as-grown films is 5.60 eV, which decreases as the annealing temperature grows, reaching 5.13 eV for thin films annealed at 600 • C with a monoclinic crystal structure. Nevertheless, the values obtained are reconciled with previous estimates of direct E g for amorphous and monoclinic hafnia in various structural modifications, such as nanopowder (in range of 5.5-5.8 eV) [7,25,39,40], thin films (5.3-5.8 eV) [41][42][43], bulk single crystal (5.89 eV) [44], etc.…”

Section: Estimation Of the Bandgap Widthsupporting

confidence: 84%

Luminescence in Anion-Deficient Hafnia Nanotubes

Shilov,

Kamalov,

Karabanalov

et al. 2023

Nanomaterials

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Hafnia-based nanostructures and other high-k dielectrics are promising wide-gap materials for developing new opto- and nanoelectronic devices. They possess a unique combination of physical and chemical properties, such as insensitivity to electrical and optical degradation, radiation damage stability, a high specific surface area, and an increased concentration of the appropriate active electron-hole centers. The present paper aims to investigate the structural, optical, and luminescent properties of anodized non-stoichiometric HfO2 nanotubes. As-grown amorphous hafnia nanotubes and nanotubes annealed at 700 °C with a monoclinic crystal lattice served as samples. It has been shown that the bandgap Eg for direct allowed transitions amounts to 5.65 ± 0.05 eV for amorphous and 5.51 ± 0.05 eV for monoclinic nanotubes. For the first time, we have studied the features of intrinsic cathodoluminescence and photoluminescence in the obtained nanotubular HfO2 structures with an atomic deficiency in the anion sublattice at temperatures of 10 and 300 K. A broad emission band with a maximum of 2.3–2.4 eV has been revealed. We have also conducted an analysis of the kinetic dependencies of the observed photoluminescence for synthesized HfO2 samples in the millisecond range at room temperature. It showed that there are several types of optically active capture and emission centers based on vacancy states in the O3f and O4f positions with different coordination numbers and a varied number of localized charge carriers (V0, V−, and V2−). The uncovered regularities can be used to optimize the functional characteristics of developed-surface luminescent media based on nanotubular and nanoporous modifications of hafnia.

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Section: Estimation Of the Bandgap Widthsupporting

confidence: 84%

Luminescence in Anion-Deficient Hafnia Nanotubes

Shilov,

Kamalov,

Karabanalov

et al. 2023

Nanomaterials

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“…From the point of view of the experimental study of perfect simulation objects, only one work is today known for the authors to judge synthesized and investigated optical properties of monoclinic single crystal hafnium dioxide [13]. Meanwhile, commercial high-purity-degree powders (99.9%) are often used for analyzing physical and chemical properties [14][15][16]. Moreover, there are widespread methods to synthesize HfO 2 thin films supported on quartz and silicon substrates by atomic layer deposition and magnetron sputtering [9,[17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Thermal quenching of self-trapped exciton luminescence in nanostructured hafnia

Shilov

Savchenko

Вохминцев

et al. 2022

Journal of Luminescence

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Quantum dots: modern methods of synthesis and optical properties

Rempel,

Ovchinnikov,

Weinstein

et al. 2024

RUSS CHEM REV

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Quantum dots are the most exciting representatives of nanomaterials. They are synthesized by modern methods of nanotechnology pertaining to both inorganic and organic chemistry. Quantum dots possess unique physical and chemical properties; therefore, they are used in very different fields of physics, chemistry, biology, engineering and medicine. It is not surprising that the Nobel Prize in chemistry in 2023 was given for discovery and synthesis of quantum dots. In this review, modern methods of synthesis of quantum dots, their optical properties and practical applications are analyzed. In the beginning, a short historical background of quantum dots is given. Many gifted scientists, including chemists and physicists, were engaged in these studies. The synthesis of quantum dots in solid and liquid matrices is described in detail. Quantum dots are well-known owing to their unique optical properties, that is why the attention in the review is focused on the quantum-size effect. The causes for fascinating blinking of quantum dots and techniques for observation of a single quantum dot are explained. The last part of the review describes important applications of quantum dots in biology, medicine and quantum technologies.<br> Bibliography — 772 references.

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Energy Gap Evaluation in Microcrystalline m-HfO2 Powder

Cited by 3 publications

References 10 publications

Luminescence in Anion-Deficient Hafnia Nanotubes

Luminescence in Anion-Deficient Hafnia Nanotubes

Thermal quenching of self-trapped exciton luminescence in nanostructured hafnia

Quantum dots: modern methods of synthesis and optical properties

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