Microstructure Properties Of ZnO Research Articles

Influence of the shaker mill in the properties of ZnO processed by high energy milling

This work evaluates how the High Energy Ball Milling (HEBM) in a shaker mill influences the optical, physical, and microstructural properties of ZnO. The procedure also combines Fe inclusion from the grinding medium with particle size reduction. ZnO powder was milled by 1, 2, 3, 4, and 5 h, which resulted in a particle size reduction to the nanometric scale with a mean size of around 50 nm and a crystallite size reduction by three times when processed from 4 h. Milling has proven to be an efficient process for obtaining nanoparticles with an incredibly short processing time and changed the morphology of the particles from random to spherical shapes. Results also indicate the processing progressively expanded the ZnO hexagonal structure due to the imposed strain and Fe inclusion, which can help to decrease the bandgap and slow down the recombination rate of the electron-hole pairs, improving the photocatalysis activity. The optical results showed no additional band appeared due to milling processes and diminished the bandgap from 3.37 to 3.21 eV. Milling also led to an increase in the c value from 5.2076 to 5.2112 Å, which is one of the most important factors for improved antibacterial activity. HEBM has proved to be a suitable process for obtaining ZnO nanoparticles with properties useful for various applications.

Структурные и микроструктурные свойства тонких пленок ZnO, полученных методом спрей-пиролиза

Структурные и микроструктурные свойства тонких пленок ZnO, полученных методом спрей-пиролиза

Microstructure Properties of ZnO/ Indium Tin Oxide and ZnO/CuInSe2 grown by Electrochemical Deposition

In this research, we grew a ZnO film as a buffer layer on indium tin oxide (ITO) substrates and CuInSe2/ITO (CIS/ITO) substrates by electrochemical deposition. To examine material quality of ZnO films, multiple material and optical analyses including scanning electron microscope images, electron probe microanalyzer images, UV-VIS, and x-ray diffraction were conducted. The results indicate that an appropriate amount of H2O2 might enhance the growth of ZnO films on the ITO substrate. Furthermore, triethanolamine addition might suppress the reaction between KCl and the CIS substrate to enhance the growth of the ZnO film on the CIS substrate. The ZnO/CIS structure may replace the toxic CdS/CIS structure for the further development for the CIS solar cell.

Influence of the substrate and nitrogen amount on the microstructural and optical properties of thin r.f.-sputtered ZnO films treated by rapid thermal annealing

N-doped ZnO (ZnO:N) thin films, intended to be used as one of the layers in solar cell applications were deposited by r.f. sputtering, using ZnN target (99.9% purity), on silicon and fused silica substrates. In the gas flow composition, Ar was kept constant (50%) and the O2/N2 ratio was varied as: 40%/10%, 25%/25% and 10%/40%. After deposition, rapid thermal annealing (RTA) at 400 and 550°C for 1min in N2 ambient has been performed. The RTA impact on the optical and microstructural properties of ZnO:N thin films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX), UV–vis–NIR spectroscopy, UV–vis–NIR spectroscopic ellipsometry (SE) and infrared ellipsometry (IR-SE). The as-deposited (ad) ZnO:N films are polycrystalline with preferentially oriented columnar crystals. After RTA we found ZnO:N films with improved crystallinity and fewer boundary defects. We report optical constants of ZnO:N from UV to IR spectral range as well as the infrared active phononic modes.

The influences of high energetic oxygen negative ions and active oxygen on the microstructure and electrical properties of ZnO:Al films by MF magnetron sputtering

In this paper, ZnO:Al transparent conducting films were prepared on glass substrate by magnetron sputtering from Al doped ZnO ceramic targets. By measuring and analyzing the structure and electrical properties of films in front of targets at different target-to-substrate distance, it was concluded that the bombardment of energetic oxygen negative ions decreased with increasing target-to-substrate distance, dominating variation of resistivity and the microstructure in erosion area, while numbers of active oxygen decrease with increasing target-to-substrate distance, explaining variation of resistivity in non-erosion area. The influence of target-to-substrate distance on electrical and microstructure properties of ZnO:Al films on drum was also investigated in order to confirming our result. The result indicated that both energetic oxygen negative ions and numbers of active oxygen determined the properties of films on drum. While target-to-substrate distance is less than 95mm, the numbers of energetic oxygen ions are the key factor and vice versa. The optimum resistivity of post-annealed films on drum was 5.1×10−4Ωcm at target-to-substrate distance of 95mm.

Microstructural properties of ZnO:Sn thin films deposited by intermittent spray pyrolysis process

Zinc oxide films have been prepared via spray pyrolysis using a perfume atomizer. ZnCl2 has been used as precursor. The influence of the precursor solution and dopant concentration has been investigated. Homogeneous films are obtained with a precursor concentration ranging between 0.3 and 0.4 M and a SnCl2 dopant concentration of 1–2%. The films exhibit broad band gaps and small conductivity. The microstructural properties of these films have been compared with that of films deposited using a classical nozzle. Films deposited by perfume atomizer are rougher, with smaller grain size, compared to films deposited with a classical nozzle.

Ageing of ZnO–NiO ceramics

Investigation of electrical, mechanical and microstructural properties of ZnO–NiO two-phase ceramics with respect to the ageing process of the material were performed. Two constituent phases, ZnOss and NiOss were identified in those ZnO–NiO ceramics which exhibit a positive temperature coefficient of electrical resistivity (PTCR anomaly). The origin of the PTCR anomaly was explained as a consequence of the different linear thermal expansion of the ZnOss and NiOss constituent phases. The ageing observed in the material is exhibited as an increase in resistivity of the samples and a smaller PTCR anomaly after heating the samples up to the temperature of the resistivity maximum, and cooling them again to room temperature. According to this study, the different linear thermal expansion of ZnOss and NiOss could also cause ageing of the material. © 1998 Kluwer Academic Publishers