Williamson-Hall analysis and optical properties of small sized ZnO nanocrystals

Kalita, Amarjyoti; Kalita, Manos P.C.

doi:10.1016/j.physe.2017.05.006

Cited by 36 publications

(14 citation statements)

References 35 publications

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“…Above this value, although a monotone decrease is observed, the variation of skin depth is minimal, with a slope of approximately 3.5 × 10 –2 . These computed distances are consistent with light penetration figures in strongly absorbing metallic films [ 44 ]. The big value obtained in the thinnest film can be explained resorting to the model of insularly deposited films.…”

Section: Resultssupporting

confidence: 83%

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Electrical Conductivity and Optical Properties of Pulsed Laser Deposited LaNi5 Nanoscale Films

Todoran

Szakács

et al. 2018

Materials

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This work presents pulsed laser deposition as a method to obtain unoxidized LaNi5 nanoscale films and describes their temperature and thickness dependent electrical conductivity and the spectral dispersions of some optical properties. AB5-type rare earth element (REE)-nickel compounds are currently studied from both theoretical and practical points of view. Special challenges are posed during the preparation of these nanomaterials, which can be overcome using finely tuned parameters in a preparation process that always involves the use of high energies. Film deposition was made by laser—induced vaporization, with short and modulated impulses and electro–optical tuning of the quality factor, mainly on glass and one SiO2 substrate. Deposition geometry dependent linear thickness increase, between 1.5–2.5 nm per laser burst, was achieved. Film structures and phase compositions were determined using XRD and discussed in comparison with films obtained by similar deposition procedures. Temperature and scale dependent properties were determined by studying electrical conductivity and optical properties. Electrical conductivity was measured using the four-probe method. The observed semiconductor-like conductivity for film thicknesses up to 110 nm can be explained by thermal activation of electrons followed by inter-insular hopping or quantum tunneling, which, on the other hand, modulates the material’s native metallic conductance. Films with thicknesses above this value can be considered essentially metallic and bulk-like. The spectral behaviors of the refractive index and absorption coefficient were deduced from differential reflectance spectroscopy data acquired on a broad ultraviolet, visible, near- and mid-infrared (UV-VIS-NIR-MIR) domain, processed using the Kramers-Krönig formalism. Their study led to the identification of the allowed interband transitions. Electronic behavior in the energy bands near the Fermi level and in the surface and interface-states was described, discussing the differences between experimental data and the classical free-electron theoretical model applied for the bulk intermetallic alloy, in correlation with theoretical optical properties or experimental X-ray photoelectron spectroscopy (XPS) results from references. However, the dielectric-like shape of the reflectance of the thinnest film was in accordance with the Lorentz–Drude model.

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Section: Resultssupporting

confidence: 83%

“…Nanoscale films always exhibit broadened peaks because of small crystallite sizes and the presence of microstrain distorting the crystal structure. These quantities were evaluated using Williamson-Hall analysis [ 44 ]. Broadening is amplified by the instrumental factor.…”

Section: Methodsmentioning

confidence: 99%

Electrical Conductivity and Optical Properties of Pulsed Laser Deposited LaNi5 Nanoscale Films

Todoran

Szakács

et al. 2018

Materials

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“…The crystal size was calculated from the diffractogram based on the diffraction line width using the Scherrer equation, Williamson–Hall (WH) (Kalita and Kalita, 2017) and the Halder–Wagner (HW) method (Motevalizadeh et al , 2014). Based on the XRD patterns, i.e.…”

Section: Resultsmentioning

confidence: 99%

Magnesium, aluminum and zinc co-substituted hydroxyapatite: anti-corrosion properties

Šimková

Šulcová

2019

ACMM

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Purpose The purpose of this study was to investigate the influence of doping ions Mg2+, Zn2+, Al3+ to the structure of hydroxyapatite (HAP; Ca10(PO4)6(OH)2) and subsequently to evaluate their adaptation in structure and their anticorrosive properties. Design/methodology/approach The substituted hydroxyapatite was synthesized by precipitation method that included the addition of Mg2+, Zn2+ and Al3+ containing precursors to partially replace Ca2+ ions in the hydroxyapatite structure. For precipitation synthesis, three ratios of Ca/P = 1; 1.67; 3 and two values of pH = 7 and 12 were selected. Samples 1 (Ca/P = 1; pH = 7), 2 (Ca/P = 1.67; pH = 7), 3 (Ca/P = 3; pH = 7) and 5 (Ca/P = 1.67; pH = 12) were chosen to monitor the influence of doping ions Mg2+, Zn2+ and Al3+ to the structure of hydroxyapatite and its anticorrosive properties. Findings The chosen synthesis conditions are appropriate for the formation of crystalline HAP substituted by elements Mg, Zn and Al. Only for one sample (1-Mg), two different phases (hydroxyapatite and whitlockite) were identified in the phase composition. On the basis of preliminary corrosion tests, pigments were divided into three groups pursuant to their anticorrosion effectivity: pigments with high corrosion-inhibition efficiency; pigments without anticorrosive properties; and pigments that promote corrosion processes. Originality/value In addition, no doping effect can be observed except for the sample 1-Mg, which consists of two phases (hydroxyapatite and whitlockite). Preliminary corrosion tests prove that some samples of HAP have extremely high anticorrosive effectivity as effectivity of the commercial pigments. The accelerated corrosion test showed that HAP samples have insufficient corrosion-inhibition properties for coating applications compared with the commercial pigment.

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“…Moreover, the materials prepared at lower pH has another two distinct peaks at 408 and 470 nm, in which wavelength at 408 nm named as violet emission is associated with electron relaxation process from conduction band tail to the valance band tail states (Kalita et. al 2017) and blue emission and at 470 nm is due to the electron transition from donor level to acceptor level of Zn vacancy (Wei et al 2007).…”

Section: Photoluminescencementioning

confidence: 99%

Stabilization of ZnO Nanoparticles Using Water Extract of Waste Coconut Husk and Photocatalytic Activity

Baglari

Brahma

Gautam

et al. 2021

Preprint

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Here, we report the synthesis of highly photoactive zinc oxide nanoparticles using water extract of waste coconut husk ash as a precipitating agent in a green approach which is a potential source of natural alkaline media. The formation of zinc oxide nanoparticles at different pH of the solution of coconut husk ash was confirmed through powder XRD, SEM-EDX, UV-Vis, FTIR and photoluminescence spectroscopy. The photocatalytic performance of the samples was evaluated through the degradation of methylene blue (MB)and methyl orange (MO) under solar irradiation which undergoes degradation around 98% and 56% within 120 min, respectively. The high photocatalytic activity and rate constant could be attributed to the large surface area due to small particle size that could provide quicker photon absorption and reduction of charge carrier recombination. This current work introduces a new method to reduce energy consumption for the synthesis of highly photoactive low-cost zinc oxide nanoparticles.

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Williamson-Hall analysis and optical properties of small sized ZnO nanocrystals

Cited by 36 publications

References 35 publications

Electrical Conductivity and Optical Properties of Pulsed Laser Deposited LaNi5 Nanoscale Films

Electrical Conductivity and Optical Properties of Pulsed Laser Deposited LaNi5 Nanoscale Films

Magnesium, aluminum and zinc co-substituted hydroxyapatite: anti-corrosion properties

Stabilization of ZnO Nanoparticles Using Water Extract of Waste Coconut Husk and Photocatalytic Activity

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