Correlation of defects and crystallite size of ZnO nanoparticles synthesized by mechanical milling

Das, Sandip; Pramanik, Subhamay; Hossain, Modassar; Mukherjee, Sumit; Rajak, Chinmoy; Pal, Prabir; Kuiri, Probodh K.

doi:10.1007/s12648-023-02763-3

Cited by 3 publications

(7 citation statements)

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“…The variation of band gap as a function of content of carbon is shown in figure 3(c) as filled circle (in red color). Also the red-shift of the band gap of ZnO NPs can be due to change in particle size, which is already reported in our previous article [17]. To confirm the actual reason behind the red-shift of band gap we have compared band gap variation due to carbon with that of due to change of particle size.…”

Section: Resultssupporting

confidence: 64%

“…In other words, the presence of larger amount of CNPs in the composite (ZnO/layered carbon), process of reduction of particle size becomes less effective by ball milling. For quantitative analysis, we have estimated the average crystallite sizes of the ZnO particles employing the Debye-Scherrer formula [17]. The estimated average crystallite sizes are 19.33 nm, 21.87 nm, 24.21 nm, and 27.89 nm corresponding to the samples ZnO_0, ZnO/C_2, ZnO/C_5, and ZnO/C_10, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…where A 1 and E 1 are two polar modes which are both Raman and infrared active, E 2 -low and E 2 -high are two nonpolar modes which are only Raman active and B 1 is a Raman silent mode [22]. The E 2low mode is caused by the vibration of Zn sublattice, while the E 2 -high mode is associated with the vibration of oxygen atoms [17]. Additionally, both the A 1 and E 1 modes have two components, namely longitudinal optical (LO) and transverse optical (TO) [17].…”

Section: Resultsmentioning

confidence: 99%

“…The E 2low mode is caused by the vibration of Zn sublattice, while the E 2 -high mode is associated with the vibration of oxygen atoms [17]. Additionally, both the A 1 and E 1 modes have two components, namely longitudinal optical (LO) and transverse optical (TO) [17].…”

Section: Resultsmentioning

confidence: 99%

“…The first peak appears at ∼362 nm, which is in the UV region and originated due to band to band transition of ZnO NPs [19]. The next peak is centered at ∼393 nm, which is also in the UV region, represents the near band edge (NBE) transition of ZnO [17]. The broad and low intense hump (peak) between 417 nm to 468 nm is created due to the emissions from the defect state of ZnO NPs.…”

Section: Resultsmentioning

confidence: 99%

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Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Das,

Pramanik,

Mukherjee

et al. 2024

J. Phys.: Condens. Matter

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ZnO/layered carbon nanocomposites with varied sizes of ZnO nanoparticles (NPs) were synthesized by mechanical milling of mixture of ZnO NPs and carbon NPs. The NP size of ZnO was controlled with average particle sizes about 19.33, 21.87, 24.21, and 27.89 nm by varying the concentrations of carbon NPs viz 0, 2, 5, and 10 weight percent, respectively, in the mixture. Presence of carbon with ZnO in the form of composite also resulted in the enhanced shift of the band gap of ZnO due to the optical transitions in the impurity states or presence of carbon as compared to the ZnO size change alone. Additionally, the enhancement of absorbance in the visible region with an increase in carbon content was observed. Such an increase in absorbance can enhance the photocatalytic activity of ZnO NPs. Raman bands for ZnO NPs also were found to shift faster in the presence of layered carbon. The quenching of visible photoluminescence emission of ZnO NPs with an increase in concentration of carbon NPs in the composite indicated the phenomenon associated with transfer of electrons from ZnO to layered carbon helping the separation of photo-generated electrons and holes in ZnO and can lead to enhancement of the photocatalytic activity of ZnO NPs. In the photocatalytic studies, it was observed that the degradation of methylene blue (MB) dye was significantly enhanced by the increase of content of layered carbon in the nanocomposite. The sample containing 10% carbon showed the highest adsorption in dark conditions which was up to 60% of the starting strength and this was further enhanced to 88% in the presence of UV radiation. Enhanced adsorption of MB dye and the effective separation of electron–hole pairs due to charge transfer were believed to be the main causes behind such kind of improvement in the photocatalytic effects.

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Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Das,

Pramanik,

Mukherjee

et al. 2024

J. Phys.: Condens. Matter

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Tuning the bandgap of 2D metallic Zn nanostructures

Pramanik,

Kuiri,

Karmakar

et al. 2023

Journal of Applied Physics

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The semiconducting behavior of two-dimensional (2D) metal nanostructures has recently attracted much interest for their possible applications in optoelectronics and others. In particular, tuning the bandgap of such nanostructures can open up a new avenue for fabricating functional nano-devices. In the present article, we report the synthesis of 2D metallic Zn nanosheets at room temperature using a ball mill, which is capable of producing large-scale materials in a single run. Initially, nanoplates were formed for ball milling the octahedral-shaped Zn nanoparticles for the time of milling of 6 h. Subsequent ball milling for another 6 h leads these nanoplates to nearly uniform nanosheets. The thickness of these 2D nanostructures was found to decrease with an increase in the time of milling. Visible photoluminescence (PL) emissions centered at ∼3, ∼2.9, and ∼2.75 eV were observed from all the Zn particles showing semiconductor behavior. The origin of such semiconductor behavior was explained based on the radiative transition of electrons from the sp band to the upper states of the 3d band. This argument was confirmed through the studies of photoelectron spectroscopy and the first principle calculations employing density functional theory (DFT). Furthermore, excitation-dependent PL studies indicated that the bandgap of the 2D Zn nanostructures decreased with the increase in the ball milling time. Therefore, a redshift in the bandgap was observed with the increase in the ball milling time. Such changes in the bandgap with the thickness of 2D Zn nanostructures were also verified from the studies of DFT. Thus, the present study demonstrated that the bandgap of 2D metallic Zn nanostructures could be effectively tuned by reducing the thickness.

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Study of the effect of synthesis temperature and thermal aging on structural, dielectric properties and phase composition in NiO/NiAl₂O₄ composite ceramics

Shakirzyanov,

Borgekov,

Garanin

et al. 2024

Mater. Res. Express

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In modern materials science, a considerable amount of research is focused on obtaining new ceramic materials to create efficient functional elements. Acquiring highly efficient and highly stable ceramic catalysts for alternative energy is an important task that demands an urgent solution. Addressing this issue promptly is essential as it will facilitate the development of new technologies that can prevent future energy crises. Nickel oxide NiO or spinels of NiAl2O4 composition are excellent candidates as high temperature catalysts used in alternative energy applications. This paper studies the synthesis of NiO/NiAl2O4 composite ceramics and the effect of high-temperature aging on their phase composition, crystalline properties, and dielectric characteristics. The study found that the phase composition and microstructure of the ceramics are unchanged by thermal aging (aged at 700 °C), while the crystalline parameters and low-frequency dielectric characteristics may undergo significant changes over time, exhibiting notable fluctuations depending on the duration of aging. The observed variations were predominantly influenced by the microstructural features of the composite ceramics. As the average grain size increased and the phase transformations were completed, the crystalline parameters and low-frequency dielectric characteristics reached a stable state without further alteration. For NiO/NiAl2O4 ceramics with a sintering temperature of 1500 °C, the highest shrinkage, low dielectric loss values and acceptable hardness were observed, indicating that the fabricated ceramics are suitable for mechanical processing. In general, the obtained composite ceramics show high temperature stability and are ready for use in hydrogen energy applications as functional elements.

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Correlation of defects and crystallite size of ZnO nanoparticles synthesized by mechanical milling

Cited by 3 publications

References 69 publications

Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Tuning the bandgap of 2D metallic Zn nanostructures

Study of the effect of synthesis temperature and thermal aging on structural, dielectric properties and phase composition in NiO/NiAl₂O₄ composite ceramics

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Correlation of defects and crystallite size of ZnO nanoparticles synthesized by mechanical milling

Cited by 3 publications

References 69 publications

Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Vibrational, optical, and photocatalytic properties of ZnO/layered carbon nanocomposite synthesized by ball milling

Tuning the bandgap of 2D metallic Zn nanostructures

Study of the effect of synthesis temperature and thermal aging on structural, dielectric properties and phase composition in NiO/NiAl2O4 composite ceramics

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Product

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Study of the effect of synthesis temperature and thermal aging on structural, dielectric properties and phase composition in NiO/NiAl₂O₄ composite ceramics