Particle size effect on the dielectric properties of ZnO nanoparticles

Ahmad, Md. Parvez; Rao, A. T.; Babu, K. Suresh; Rao, G. Narsinga

doi:10.1016/j.matchemphys.2018.12.002

Cited by 73 publications

(15 citation statements)

References 17 publications

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“…In our experimental results, we attain one semicircle, which concludes that maximum conduction is through grain boundary in all Ni 1−x Zn x Fe 2 O 4 samples [73,80]. Moreover, it may occur also due to transport of charge carriers, conduction band overlapping in bulk, or electrode interfaces [52,81]. The oxygen stoichiometry also significantly affects the electric, magnetic, or magnetoelectric properties of nanoferrites, hexaferrites, and complex oxides [24,82].…”

Section: Resultsmentioning

confidence: 81%

Influence of Zn+2 Doping on Ni-Based Nanoferrites; (Ni1−x ZnxFe2O4)

2019

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Nickel zinc nanoferrites (Ni1−xZnxFe2O4) were synthesized via a chemical co-precipitation method having stoichiometric proportion (x) altering from 0.00 to 1.00 in steps of 0.25. The synthesized nanoparticles were sintered at 800 °C for 12 h. X-ray diffraction patterns illustrate that the nanocrystalline cubic spinel ferrites have been obtained after sintering. The Scherrer formula is used to evaluate the particle size using the extreme intense peak (311). The experimental results demonstrate that precipitated particles’ size was in the range of 20–60 nm. Scanning electron microscopy (SEM) is used to investigate the elemental configuration and morphological characterizations of all the prepared samples. FTIR spectroscopy data for respective sites were examined in the range of 300–1000 cm−1. The higher frequency band ν1 were assigned due to tetrahedral complexes while lower frequency band ν2 were allocated due to octahedral complexes. Our experimental results demonstrate that the lattice constant a0 increases while lattice strain decreases with increasing zinc substitution in nickel zinc nanoferrites.

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Section: Resultsmentioning

confidence: 81%

Influence of Zn+2 Doping on Ni-Based Nanoferrites; (Ni1−x ZnxFe2O4)

2019

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“…The deviation from the linearities of MS plots could be due to the presence of large concentration surface states of the sample and the surface roughness of the nanoparticle thin film. The donor density of pure ZnO and Co-doped ZnO nanoparticles was estimated using the dielectric constant 3.8 reported for 22 nm sized ZnO NPs . As seen in Figure c, the donor density of doped zinc oxide gradually increases with doping compared to pure zinc oxide, and this could be due to cobalt ions reducing or passivating defects, which leads to larger carrier densities.…”

Section: Resultsmentioning

confidence: 99%

“…The donor density of pure ZnO and Co-doped ZnO nanoparticles was estimated using the dielectric constant 3.8 reported for 22 nm sized ZnO NPs. 65 As seen in Figure 9c, the donor density of doped zinc oxide gradually increases with doping compared to pure zinc oxide, and this could be due to cobalt ions reducing or passivating defects, which leads to larger carrier densities. A further increase in doping will create cobalt-based defects, which will reduce the carrier density.…”

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confidence: 88%

Suppression of Visible Emission in Low-Temperature Synthesized Cobalt-Doped ZnO Nanoparticles and Their Photosensing Applications

Devi Chandra,

Veena,

Gopchandran

2023

Inorg. Chem.

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Cobalt (Co)-doped ZnO nanoparticles have been synthesized at 100 °C using a simple chemical technique, without post-deposition annealing. These nanoparticles are of excellent crystallinity and show a significant reduction in defect density upon Co-doping. By varying the Co solution concentration, it is observed that oxygen-vacancy-related defects are suppressed at lower Co-doping, while the defect density shows an increasing trend at higher doping densities. This suggests that mild doping can significantly suppress the defects in ZnO for electronic and optoelectronic applications. The effect of Co-doping is studied using X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), electrical conductivity, and Mott–Schottky plots. Photodetectors fabricated using pure and Co-doped ZnO nanoparticles show a noticeable reduction in the response time upon Co-doping, which again affirms the reduction in the defect density after Co-doping.

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“…However, this value has to be screened, and very different values of the dielectric constant ε s can be found in the literature. For bulk ZnO ε s = 8–10 , but it can range from 5 to 50 for nanoparticles, − depending on their size. Hence, the screened values of U could range between 2ω 0 and 15ω 0 .…”

Section: Resultsmentioning

confidence: 99%

Electron–Electron and Electron–Phonon Interactions in the Dynamics of Trap-Filling in Charged Quantum Dots

Monreal

2024

J. Phys. Chem. C

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We analyze theoretically the effects of electron− electron and electron−phonon interactions in the dynamics of a system of a few electrons that can be trapped in a localized state and detrapped in an extended band state of a small quantum dot (QD) using a simple model. In our model, the QD is described by one or two single-particle energy levels, while the trap is described by one single-particle level connected to the QD by a hopping Hamiltonian. Electron−electron Coulomb repulsion and electron− phonon interactions are included in the localized trap state. In spite of its simplicity, the time-dependent model has no analytical solution, but a numerically exact one can be found at a relatively low computational cost. Using values of the parameters appropriate for defects in semiconductor QDs, we find that the electronic motion is quasi-periodic in time, with oscillations around mean values that are set in time scales of typically a few tenths of picoseconds. We increase the number of electrons initially in the QD from one to four and find that one electron is transferred to the trap state for three electrons in the QD. At the more efficient values of the electron−phonon coupling, these characteristics are quite independent of the value of the electron−electron Coulomb repulsion in the trap up to the value above which its infinite limit is reached. We conclude that strong electron−phonon interaction is an efficient mechanism that can provide the complete filling of a deep trap state on a sub-to picosecond time scale, faster than radiative exciton decay and Auger recombination processes. This leads to a complete suppression of the luminescence to the deep trap state and the accumulation of electrons in the QD.

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Particle size effect on the dielectric properties of ZnO nanoparticles

Cited by 73 publications

References 17 publications

Influence of Zn+2 Doping on Ni-Based Nanoferrites; (Ni1−x ZnxFe2O4)

Influence of Zn+2 Doping on Ni-Based Nanoferrites; (Ni1−x ZnxFe2O4)

Suppression of Visible Emission in Low-Temperature Synthesized Cobalt-Doped ZnO Nanoparticles and Their Photosensing Applications

Electron–Electron and Electron–Phonon Interactions in the Dynamics of Trap-Filling in Charged Quantum Dots

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