Preparation and Characterisation of Al doped ZnO Nanopowders

Chitra, M.; Uthayarani, K.; Rajasekaran, N.; Girija, E. K.

doi:10.1016/j.phpro.2013.10.024

Cited by 13 publications

(8 citation statements)

References 15 publications

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“…This effect could be owing to the fact that tantalum atoms create a compression stress inside the lattice of ZnO, and they prevents an increase in these big shapes, as generated by the difference of ionic radii between Zn and Ta, as commented before in the XRD results. In fact, this phenomenon also has been observed when ZnO is doped with tantalum by other techniques [56], or when ZnO is doped with other materials such as aluminum and lithium [35,42]. compression stress inside the lattice of ZnO, and they prevents an increase in these big shapes, as generated by the difference of ionic radii between Zn and Ta, as commented before in the XRD results.…”

Section: Sem and Eds Studiessupporting

confidence: 62%

“…compression stress inside the lattice of ZnO, and they prevents an increase in these big shapes, as generated by the difference of ionic radii between Zn and Ta, as commented before in the XRD results. In fact, this phenomenon also has been observed when ZnO is doped with tantalum by other techniques [56], or when ZnO is doped with other materials such as aluminum and lithium [35,42]. The synthesis of smaller structures means that somehow, the relation between the surface/volume of the film will increase, and this fact will be reflected in an increment of reactions between the existing species on the surface of structures, and also a possible increment in the adsorption and resorption of the species in these kind of porous films, and moreover, an increment of cations or anions on the surface of the film, as has been reported in other works; in fact, the role of the surface area has been observed to affect various mechanisms such as gas sensors, biological cells, and the effects of fluorescence emission [28,[59][60][61].…”

Section: Sem and Eds Studiesmentioning

confidence: 74%

“…The luminescence was ascribed mainly to the existence of oxygen vacancies. Other transition metals when introduced to ZnO, such as Al, Li, Co, Mn, and Zn, have also been reported to exhibit emissions in different ranges; however, the wavelengths of emission and intensity depended on the process and technique of the growth [10,[33][34][35]. Similarly, yellow emission was been observed when the ZnO synthesis was performed by chemical techniques.…”

Section: Introductionmentioning

confidence: 99%

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Highly Visible Photoluminescence from Ta-Doped Structures of ZnO Films Grown by HFCVD

et al. 2018

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Tantalum-doped ZnO structures (ZnO:Ta) were synthesized, and some of their characteristics were studied. ZnO material was deposited on silicon substrates by using a hot filament chemical vapor deposition (HFCVD) reactor. The raw materials were a pellet made of a mixture of ZnO and Ta2O5 powders, and molecular hydrogen was used as a reactant gas. The percentage of tantalum varied from 0 to 500 mg by varying the percentages of tantalum oxide in the mixture of the pellet source, by holding a fixed amount of 500 mg of ZnO in all experiments. X-ray diffractograms confirmed the presence of zinc oxide in the wurtzite phase, and metallic zinc with a hexagonal structure, and no other phase was detected. Displacements to lower angles of reflection peaks, compared with those from samples without doping, were interpreted as the inclusion of the Ta atoms in the matrix of the ZnO. This fact was confirmed by energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) measurements. From scanning electron microscopy (SEM) images from undoped samples, mostly micro-sized semi-spherical structures were seen, while doped samples displayed a trend to grow as nanocrystalline rods. The presence of tantalum during the synthesis affected the growth direction. Green photoluminescence was observed by the naked eye when Ta-doped samples were illuminated by ultraviolet radiation and confirmed by photoluminescence (PL) spectra. The PL intensity on the Ta-doped ZnO increased from those undoped samples up to eight times.

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Section: Sem and Eds Studiessupporting

confidence: 62%

Section: Sem and Eds Studiesmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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Highly Visible Photoluminescence from Ta-Doped Structures of ZnO Films Grown by HFCVD

et al. 2018

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“…The increase in absorbance in the visible region for the Al-doped ZnO may be due to different factors including particle size and defects in crystal structure (Mir & Batoo, 2016). It is well known that Al atoms located on ZnO particles surface exhibit surface plasmon resonance and can show an intense absorption in the visible region (Chitra, Uthayarani, Rajasekaran, & Girija, 2013). The optical band gap (E g ), determined from the absorbance spectrum which is equal to the difference between the HOMO and LUMO energy levels, corresponds to the first optical transition of lower energy that can be absorbed by the material [Z].…”

Section: Resultsmentioning

confidence: 99%

Particularities of pure and Al-doped ZnO nanostructures aerogels elaborated in supercritical isopropanol

Mouzaia

Djouadi

Chelouche

et al. 2020

Arab Journal of Basic and Applied Sciences

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Undoped and Al-doped ZnO nanoparticles are synthesized in supercritical isopropanol using zinc acetate di-hydrate, aluminum nitrates and methanol as precursor, dopant source and solvent, respectively. The atomic ratio [Al]/[Zn] is fixed to 3%. X-ray diffraction (XRD) results indicate that the synthesized ZnO nanoparticles possess hexagonal wurtzite structure. Aldoping of ZnO aerogel leads to the improvement of the crystalline quality due to the occupation of Zn 2þ sites by Al 3þ ions. The crystallites size is found to be 32 nm in pure ZnO and 50 nm in the doped aerogel. Fourier-transform infrared spectroscopy spectra reveal that the intensity of the absorption bands in ZnO decreases and the Zn-O vibration band position shifts towards higher wave numbers upon Al-doping. UV-Visible measurements show a reduction in the band gap and a shift towards long wavelength side of the absorbance with Al-doping. Scanning electron microscopy images reveal that aerogel grains are quasi-spherical in pure ZnO and have different and random forms of morphologies in the doped sample. Room temperature photoluminescence (PL) studies put into evidence that the PL emission peaks are influenced by the Al-doping, in particular, a decrease in the green emission at 535 nm is observed.

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“…It is well-known that doping treatment is usually initiated to induce luminescence modifications resulting in the improvement of material properties thereby higher performance for potential applications [7]. It has been reported that ZnO was doped by various dopant such as In [8], Al [9,10], Mn [11], Eu [12], Ti [13], Fe [14], Mg [15], etc. Besides of all the dopants, the ZnO:Ca 2+ system is very interesting because Ca 2+ element have a higher ionic size than the host Zn 2+ cation and doping of ZnO using Ca 2+ species in particular is more effective for the stabilization of lattice systems and increases the ionicity of chemical bonds in ZnO system [16].…”

Section: Introductionmentioning

confidence: 99%