Magnesium-doped zinc oxide "ZnO:Mg" nanocrystals (NCs) were fabricated using a sol gel method. The Mg concentration impact on the structural, morphological, electrical, and dielectric characteristics ...of ZnO:Mg NCs were inspected. X-ray diffraction (XRD) patterns display the hexagonal wurtzite structure without any additional phase. TEM images revealed the nanometric size of the particles with a spherical-like shape. The electrical conductivity of the ZnO NCs, thermally activated, was found to be dependent on the Mg content. The impedance spectra were represented via a corresponding circuit formed by a resistor and constant phase element (CPE). A non-Debye type relaxation was located through the analyses of the complex impedance. The conductivity diminished with the incorporation of the Mg element. The AC conductivity is reduced by raising the temperature. Its plot obeys the Arrhenius law demonstrating a single activation energy during the conduction process. The complex impedance highlighted the existence of a Debye-type dielectric dispersion. The various ZnO:Mg samples demonstrate high values of dielectric constant with small dielectric losses for both medium and high-frequency regions. Interestingly, the Mg doping with 3% content exhibits colossal dielectric constant (more than 2 × 10
) over wide temperature and frequency ranges, with Debye-like relaxation. The study of the electrical modulus versus the frequency and at different temperatures confirms the non-Debye relaxation. The obtained results reveal the importance of the ZnO:Mg NCs for device applications. This encourages their application in energy storage.
In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al
O
(10:2 wt %) material. The films were ...deposited on glass and silicon substrates at the different working pressures of 0.21, 0.61, 0.83 and 1 Pa, 300 °C and 250 W of power. X-ray diffraction patterns (XRD), atomic force microscopy (AFM), UV-vis absorption and Hall effect measurements were used to evaluate the structural, optical, morphological and electrical properties of thin films as a function of the working pressure. The optical properties of the films, such as the refractive index, the extinction coefficient and the band gap energy were systematically studied. The optical band gap of thin films was estimated from the calculated absorption coefficient. That parameter, ranged from 3.921 to 3.655 eV, was hardly influenced by the working pressure. On the other hand, the lowest resistivity of 8.8 × 10
Ω cm
was achieved by the sample deposited at the lowest working pressure of 0.21 Pa. This film exhibited the best optoelectronic properties. All these data revealed that the prepared thin layers would offer a good capability to be used in photovoltaic applications.
•ZnO nancrystals doped with Mg were prepared from sol–gel method.•Structural and optical properties of ZnO:Mg nanocrystals were investigated.•Good crystalline quality of ZnO nanocrystals was reported ...after Mg doping.•Good photocatalytic activity of Mg doped ZnO nanocrystals was demonstrated under sun light illumination.
Undoped and Mg doped ZnO nanocrystals (NCs) ZnO:x%Mg (x=1, 2, 3, and 5) were synthesized using sol–gel method. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectivity, and photoluminescence (PL). XRD analysis demonstrates that all prepared samples present pure hexagonal wurtzite structure without any Mg related phases. The NCs size varies from 26.82nm to 42.96nm with Mg concentrations; it presents an optimal value for 2% of Mg. The Raman spectra are dominated by the E2high mode. For highly Mg doping (5%), the occurrence of silent B1(low) mode suggested that the Mg ions do substitute at Zn sites in the ZnO lattice The band gap energy was estimated from both Tauc and Urbach methods and found to be 3.39eV for ZnO:2%Mg. The PL spectra exhibit two emission bands in the UV and visible range. Their evolution with Mg doping reveals the reduction of defect density in ZnO at low Mg doping by filling Zn vacancies.
In addition, it was found that further Mg doping, above 2%, improves the photocatalytic activity of ZnO NCs for photodegradation of Rhodamine B (RhB) under sunlight irradiation. The efficient electron–hole separation is the main factor responsible for the enhancement of photocatalytic performance of Mg doped ZnO NCs.
Through this work, we show that by varying the Mg contents in ZnO, this material can be a potential candidate for both optoelectronic and photocatalytic applications.
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•ZnMgO nanoparticles were successfully prepared via solgel method.•Structural and optical properties of ZnO-ZnMgO-MgO nanocomposites were investigated.•High photocatalytic activity of ...ZnO-ZnMgO-MgO nanocomposites is seen under sun light irradiation.•The presence of high amount of MgO blocked the process of charge transfer.
ZnO-ZnMgO-MgO nanocomposites have been successfully synthesized using the sol-gel method. An enlargement, with Mg content, of the XRD band relative to (002) diffraction revealed the formation of ZnMgO phase. HRTEM images prove the formation of ZnO and MgO nanocrystals. Raman spectrum show a weakened surface vibration and broadened LO peak with high Mg concentration. UV–vis measurements demonstrate the appearance of double band gap relatives to ZnO and ZnMgO phases. A high sensitivity of the UV emission band to Mg content was detected through the PL analysis. The photocatalytic activity of the samples was evaluated for aqueous Rhodamine B solution under sunlight irradiation. ZnO-ZnMgO-MgOnanocomposites with of 20% of Mg content display the best activity with a full degradation after 80 min of irradiance. The present work could provide an easy and low-cost way for the fabrication, high efficiency of ZnO-MgOphotocatalyst with the appearance of the ternary alloy ZnMgO phase.
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