Abstract:ZnO, as an important semiconductor material, has attracted much attention due to its excellent physical properties, which can be widely used in many fields. Notably, the defects concentration and type greatly affect the intrinsic properties of ZnO. Thus, controllable adjustment of ZnO defects is particularly important for studying its photoelectric properties. In this work, we fabricated ZnO ceramics (ZnO(C)) with different defects through spark plasma sintering (SPS) process by varying sintering temperature a… Show more
“…Therefore, structural defects engineering based on the formation of intrinsic defects is a way to modify the structural and luminescent properties of materials. For example, the generation of defects in ZnO allows modifying its luminescence spectra [8][9][10][11]. In addition to the formation of such defects as vacancies, interstitial hydrogen or other elements, it is possible to change smaterials' properties by using the partial substitution of some ions by ions with similar properties [12][13][14][15].…”
Fine-dispersed YGdAG:Ce nanopowders with various degrees of isomorphic substitution of yttrium by gadolinium were synthesized. The structure and luminescent properties were studied by X-ray diffraction, attenuated total reflection Fourier-transform infrared spectroscopy, luminescence spectroscopy and scanning electron microscopy. The possibility of synthesis of YGdAG:Ce nanopowders with a degree of gadolinium substitution up to 60% and nanocrystals with average sizes of 25–30 nm were shown. The red-shift of the cerium luminescence band with an increase in Gd content was studied. The CIE diagram for emission of YGdAG:Ce synthesized by the polymer–salt method shows that the degree 30–40% substitution of Y by Gd is optimal for the fabrication of a white light source based on LED with an emission wavelength of 470 nm.
“…Therefore, structural defects engineering based on the formation of intrinsic defects is a way to modify the structural and luminescent properties of materials. For example, the generation of defects in ZnO allows modifying its luminescence spectra [8][9][10][11]. In addition to the formation of such defects as vacancies, interstitial hydrogen or other elements, it is possible to change smaterials' properties by using the partial substitution of some ions by ions with similar properties [12][13][14][15].…”
Fine-dispersed YGdAG:Ce nanopowders with various degrees of isomorphic substitution of yttrium by gadolinium were synthesized. The structure and luminescent properties were studied by X-ray diffraction, attenuated total reflection Fourier-transform infrared spectroscopy, luminescence spectroscopy and scanning electron microscopy. The possibility of synthesis of YGdAG:Ce nanopowders with a degree of gadolinium substitution up to 60% and nanocrystals with average sizes of 25–30 nm were shown. The red-shift of the cerium luminescence band with an increase in Gd content was studied. The CIE diagram for emission of YGdAG:Ce synthesized by the polymer–salt method shows that the degree 30–40% substitution of Y by Gd is optimal for the fabrication of a white light source based on LED with an emission wavelength of 470 nm.
“…Наличие структурных дефектов также оказывает существенное влияние на оптические, электрические и фотокаталитические свойства ZnO [9,10]. Для оксида цинка характерны такие структурные дефекты, как кислородные вакансии (V o ), межрешеточный цинк (Zn i ) и водород (H i ) [11,12].…”
The synthesis of ZnO-MgO nanocomposite via modified Pechini method was performed. The crystalline structure and the morphology of nanocrystals were studied by X-ray diffraction analysis and scanning electron microscopy. The study on the kinetics of diazo dye adsorption and its photocatalytic decomposition on the surface of nanocomposite was performed. It was shown that the rate of adsorption process in aqueous solution is described by a kinetic equation of the first order. The application of the nanocomposite allows to significantly increase the efficiency of UV water treatment and its purification from the dye. However, a brief deviation of experimental data on the rate of photocatalytic degradation from the values of the widely used kinetic equation of the first order is observed.
“…In electrochemical devices, oxidation and reduction occur on the surfaces of photosensitive electrodes with the help of extra photoinduced charged carriers, which can be used to enhance chemical reactions and sensing performance. Therefore, the most common materials, including titanium oxide (TiO 2 ) [ 12 , 13 ], ferric oxide (Fe 2 O 3 ) [ 14 , 15 ] and zinc oxide (ZnO) [ 16 , 17 ], have been investigated widely for decades due to their natural abundance, high chemical stabilities, low costs and low toxicities, especially for realizing superior performance by means of various nanostructures [ 18 ]. TiO 2 is the most promising material due to its various fabrication techniques and biocompatibility [ 19 ].…”
In this study, a new anodic oxidation with a step-bias increment is proposed to evaluate oxidized titanium (Ti) nanostructures on transparent fluorine-doped tin oxide (FTO) on glass. The optimal Ti thickness was determined to be 130 nm. Compared to the use of a conventional constant bias of 25 V, a bias ranging from 5 V to 20 V with a step size of 5 V for 3 min per period can be used to prepare a titanium oxide (TiOx) layer with nanohollows that shows a large increase in current of 142% under UV illumination provided by a 365 nm LED at a power of 83 mW. Based on AFM and SEM, the TiOx grains formed in the step-bias anodic oxidation were found to lead to nanohollow generation. Results obtained from EDS mapping, HR-TEM and XPS all verified the TiOx composition and supported nanohollow formation. The nanohollows formed in a thin TiOx layer can lead to a high surface roughness and photon absorbance for photocurrent generation. With this step-bias anodic oxidation methodology, TiOx with nanohollows can be obtained easily without any extra cost for realizing a high current under photoelectrochemical measurements that shows potential for electrochemical-based sensing applications.
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