Dislocations and particle size governed band gap and ferromagnetic ordering in Ni doped ZnO nanoparticles synthesized via co-precipitation

Chattopadhyay, Saikat; Misra, Kamakhya Prakash; Agarwala, Arunava; Shahee, Aga; Jain, S. K.; Halder, N. C.; Rao, Ashok; Babu, P. D.; Saran, Mukesh; Mukhopadhyay, Anoop Kumar

doi:10.1016/j.ceramint.2019.08.034

Cited by 49 publications

(18 citation statements)

References 60 publications

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“…As for the latter reason, it was shown in Ref. [35] that the effect of dislocations on the bandgap of ZnO is only minor, i.e. an increase in dislocations density form ∼ 2.4 × 10 15 to ∼ 5.3 × 10 15 1/m 2 causes a minor bandgap narrowing from 3.26 to 3.20 eV, one order of magnitude smaller than observed in the present work.…”

Section: Resultscontrasting

confidence: 46%

“…Further possible reasons for the observed bandgap narrowing include: (i) Cu diffusion into ZnO during HPT processing and its chemical modification [34], and (ii) gradient of dislocations density across the ZnO particle and concomitant variation of the bandgap [35]. As for the former reason, our previous study reveals that no intermixing occurred between the cladding Cu disk and ZnO clusters [10].…”

Section: Resultsmentioning

confidence: 93%

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Gradient bandgap narrowing in severely deformed ZnO nanoparticles

Kauffmann

Kosinova

et al. 2020

Materials Research Letters

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Gradient nanostructured metallic materials with a gradual change of grain boundary and dislocation density display unprecedent mechanical properties. Herein, we uncover a gradient of point defects concentration and concomitant gradient bandgap (E g) narrowing in metal oxide nanoparticles processed by a combination of severe shearing and frictional sliding deformation. Using the valence electron-energy loss spectroscopy technique, we find a gradual decrease of E g from 2.93 eV in the interior to 2.43 eV at the edge of the high-pressure torsion processed ZnO flake-shaped particle. This work paves the way to strain engineering of gradient-structured metal oxide semiconductors for unique functional properties. IMPACT STATEMENT We uncover a gradient of oxygen vacancy concentration and concomitant bandgap narrowing in an individual metal oxide nanoparticle processed by a combination of severe shearing and frictional sliding deformation.

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Section: Resultscontrasting

confidence: 46%

Section: Resultsmentioning

confidence: 93%

Gradient bandgap narrowing in severely deformed ZnO nanoparticles

Kauffmann

Kosinova

et al. 2020

Materials Research Letters

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“…To estimate the band gap of pure ZnO and ZnO/psyllium husk hybrid samples, Tauc’s plot is performed. The absorption coefficient α for direct band gap materials relates to optical band gap energy according to the expression [ 31 ].…”

Section: Methodsmentioning

confidence: 99%

Psyllium-Husk-Assisted Synthesis of ZnO Microstructures with Improved Photocatalytic Properties for the Degradation of Methylene Blue (MB)

et al. 2022

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Wastewater from the textile industry is chronic and hazardous for the human body due to the presence of a variety of organic dyes; therefore, its complete treatment requires efficient, simple, and low cost technology. For this purpose, we grew ZnO microstructures in the presence of psyllium husk, and the role of psyllium husk was to modify the surface of the ZnO microstructures, create defects in the semiconducting crystal structures, and to alter the morphology of the nanostructured material. The growth process involved a hydrothermal method followed by calcination in air. Additionally, the psyllium husk, after thermal combustion, added a certain value of carbon into the ZnO nanomaterial, consequently enhancing the photocatalytic activity towards the degradation of methylene blue. We also investigated the effect of varying doses of photocatalyst on the photocatalytic properties towards the photodegradation of methylene blue in aqueous solution under the illumination of ultraviolet light. The structure and morphology of the prepared ZnO microstructures were explored by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) techniques. The degradation of methylene blue was monitored under the irradiation of ultraviolet light and in the dark. Also, the degradation of methylene blue was measured with and without photocatalyst. The photodegradation of methylene blue is highly increased using the ZnO sample prepared with psyllium husk. The photodegradation efficiency is found to be approximately 99.35% for this sample. The outperforming functionality of psyllium-husk-assisted ZnO sample is attributed to large surface area of carbon material from the psyllium husk and the synergetic effect between the incorporated carbon and ZnO itself. Based on the performance of the hybrid material, it is safe to say that psyllium husk has high potential for use where surface roughness, morphology alteration, and defects in the crystal structure are vital for the enhancing the functionality of a nanostructured material. The observed performance of ZnO in the presence of psyllium husk provides evidence for the fabrication of a low cost and efficient photocatalyst for the wastewater treatment problems.

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“…[18] Alternatively, the combination of different semiconductors gives rise to p-n or p-p heterojunction. [19,20] A number of different metal oxides have so far been shown to form heterojunctions with NiO, such as zinc, tin, iron, and copper oxides. [21] The CuO-based heterojunctions are of great interest since copper oxide is a p-type semiconductor and offers a very narrow bandgap in the range of 1.2-1.5 eV along with conductivity around 10 À4 s cm À1 [22,23] These outstanding properties have drawn increasing attention for wide range of applications such as semiconductor, catalysis, and gas sensors.…”

Section: Introductionmentioning

confidence: 99%

Composition Dependence of Structural, Optical, Magnetic and Photodegradation Properties of Nanocrystalline NiO/CuO Heterostructured Powders

Tangcharoen

Klysubun

Kongmark

2022

Physica Status Solidi (a)

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Nanocrystalline NiO/CuO solid solutions and heterostructured powders are prepared by a sol–gel auto combustion method. Herein, the NiO/CuO compounds at various molar ratio, including 100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10, 80/20, 50/50, 20/80, 10/90, 5/95 and 0/100, are investigated. The structures, morphologies, optical, and magnetic properties of all samples are explored. The detailed structures of the NiO/CuO system are deduced from Rietveld refinements of X‐ray diffraction (XRD) data and the combination of experimental and simulation studies of X‐ray absorption spectroscopy (XAS) spectra. It is found that a small addition of CuO in NiO enhances the formation of rock salt CuxNi1–xO solid solutions with 0 ≤ x ≤ 0.1. The NiO/CuO composites with CuO mole fractions (m) of 20% ≤ m ≤ 95% are affirmed by the coexistence of NiO rock salt and CuO tenorite phases. The composites rich in CuO exhibit strong adsorption in the visible and ultraviolet spectral regions, while the absorption of composites rich in NiO is absent in certain regions of visible and infrared light. In addition, the superparamagnetism of NiO can be tuned to ferromagnetism by a small addition of CuO. The photocatalytic degradation efficiencies of rhodamine B, methylene blue, methyl orange, and methyl red over NiO/CuO reach 92%–97% within a period of 150 min under sunlight irradiation.

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Dislocations and particle size governed band gap and ferromagnetic ordering in Ni doped ZnO nanoparticles synthesized via co-precipitation

Cited by 49 publications

References 60 publications

Gradient bandgap narrowing in severely deformed ZnO nanoparticles

Gradient bandgap narrowing in severely deformed ZnO nanoparticles

Psyllium-Husk-Assisted Synthesis of ZnO Microstructures with Improved Photocatalytic Properties for the Degradation of Methylene Blue (MB)

Composition Dependence of Structural, Optical, Magnetic and Photodegradation Properties of Nanocrystalline NiO/CuO Heterostructured Powders

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