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Zinc Oxide-Based Nanocomposites for Photocatalytic Conversion of Organic Pollutants in Water
Published in Chaudhery Mustansar Hussain, Ajay Kumar Mishra, Nanocomposites for Pollution Control, 2018
Zinc oxide (ZnO) is an oxidic compound naturally occurring as the rare mineral zincite, which crystallizes in three different structures: wurtzite, zincblende, and rocksalt. It usually appears as a white powder, nearly insoluble in water but soluble in acids and alkalis. ZnO is the most frequently used among the zinc compounds and commercially produced using the French process—the metallic zinc is vaporized in a large container by external heating. In an adjoining off-take pipe or combustion chamber, the vapor is burned off in the air to a fine ZnO powder [1] and American process—oxidized ores of roasted sulfide concentrates are mixed with anthracite coal (carbon additive) and smelted in a furnace. The coal together with the products of partial combustion mainly carbon monoxide reduced the ore to metallic zinc, which is released as vapor. The zinc vapor is then re-oxidized by lower temperature air and formed ZnO particulate. The purity of the ZnO produced by this process is normally rather inferior to that from the French process as it contained low levels of lead and sulfur [1,2].
The Future of Electronics
Published in John D. Cressler, Silicon Earth, 2017
Zinc oxide (ZnO) is a material to consider. ZnO is a white powder which is insoluble in water, and occurs naturally as the mineral zincite. Turns out, though, that most zinc oxide is produced synthetically. Why? Well, it is widely used as an additive in making rubber, plastics, ceramics, glass, cement, lubricants, paints, ointments (remember that screaming-white sunscreen your folks smeared across your nose while at the beach!), adhesives, sealants, pigments, foods, batteries, ferrites, fire retardants, and first-aid tapes. You get the idea. Lots of apps. Why add ZnO? Helps their properties, of course. BUT, it turns out that ZnO is also a wide-bandgap semiconductor (direct bandgap of about 3.3 eV). A Group II–VI semiconductor, to be specific. The native doping of ZnO is due to oxygen vacancies or zinc interstitials, making it naturally n-type, though controllable to suit our needs). Importantly, ZnO has interesting electrical and optical properties, including transparency, high electron mobility, wide bandgap, and strong room-temperature luminescence; properties which can be used to help enable emerging applications such as transparent electrodes for liquid crystal displays (LCDs), energysaving or heat-protecting windows, thin-film transistors, and light-emitting diodes. Nope, not a CMOS replacement, but still cool and potentially important in the grand scheme of the micro/nano world.
Zinc Oxide (ZnO)
Published in Zbigniew Galazka, Transparent Semiconducting Oxides, 2020
The substance ZnO occurs in nature as the rare mineral zincite. Its crystals are typically needles with hexagonal cross section. The color varies mainly from yellow to red, which is the result of iron or manganese impurities. Zincite is sometimes formed also in zinc smelters, because liquid zinc (melting point 419.6°C) evaporates easily (boiling point 908°C under atmospheric pressure) and reacts with oxygen if air is introduced through leaks. Such “artificial zincite” needles are sometimes more than 5 cm long.
Analysis of the physicochemical properties of antimicrobial compositions with zinc oxide nanoparticles
Published in Science and Technology of Advanced Materials, 2019
Jolanta Pulit-Prociak, Jarosław Chwastowski, Laura Bittencourt Rodrigues, Marcin Banach
Bacterial and microbial infections are considered to be a serious threat to human health because of mutations and the resistance developed by these microorganisms through years of overexposure to antibiotics. Researchers are constantly working on the development of antimicrobial agents, and they often revisit known biocide components to study their mechanisms of action or to search for new ways to apply such substances. Owing to its microbicide properties, nano-ZnO can be used in food packing, textiles, cosmetics, personal care products, and biomedical applications [6,7]. Zinc oxide (ZnO) is a naturally occurring metal oxide found in mineral form as zincite. It is commonly used in industry for the production of rubbers, concrete, and paints [8]. Because of its electrical properties, it is widely studied in semiconductor research and development. In the pharmaceutical industry, ZnO is currently found in many applications such as in lotions, sunscreens, and other healthcare products [9]. According to the U.S. Food and Drug Administration (U.S. FDA) [10], zinc oxide is a Generally Recognized As Safe (GRAS) substance. Zinc oxide has a tendency to grow self-organized nanostructures. The unique and enhanced properties of ZnO nanoparticles (NPs) have opened more fields of study and applications for the material, such as in ceramics, pharmaceutical formulations, bioimaging and antimicrobial treatments. Similar to other nano-sized substances, nano-scaled ZnO presents new physicochemical, electrical, optical and structural properties, because the surface area/volume ratio is increased. Because of that, small quantities of ZnO NPs can present powerful properties when compared to the bulk material [9,11].
Use of nanomaterial for asphalt binder and mixtures: a comprehensive review on development, prospect, and challenges
Published in Road Materials and Pavement Design, 2021
Prabin Kumar Ashish, Dharamveer Singh
ZnO is an oxide form of inorganic compound zinc present in white coloured powdered crystalline form. ZnO also occurs naturally as the mineral “zincite”. ZnO crystal exists in two different forms: hexagonal wurtzite and cubic zincblende (Fierro, 2006). Out of these two forms, hexagonal wurtzite is most commonly available ZnO due to its stability against the ambient temperature-pressure condition. Ordinary ZnO white powder can be produced at laboratory scale through electrolysing a solution of sodium bicarbonate with a zinc anode as expressed by Equations (2) and (3).
Growth temperature on ZnO:Al thin films morphology and optical properties
Published in Surface Engineering, 2021
This study investigated the effect of Al incorporation and the bath growth temperature on the structure, morphology, and optical properties of pure and Al-doped ZnO films. The pure and Al-doped ZnO thin films were synthesized through a sol–gel deposition route and grown on glass substrates by spin coating then water bath treatment. XRD patterns revealed that all samples have Zincite ZnO crystal structure and exhibited (002) preferential orientation. The patterns also indicated that Al-doping decreases the crystallite size of the ZnO samples and increases their lattice strain and dislocation density at the bath growth temperature of 40 and 60°С, and lattice strain decreases at 90°С. It confirmed good incorporation of the Al dopant into the lattice of ZnO. Also, the EDS spectra at bath growth temperature of 40°С approved incorporation of Al into the Al-doped ZnO samples. The 3% Al-doping sample with bath growth temperature only at 40°С exhibited a nano-rod structure (the mean diameter of 14 nm, length 80 nm). UV-vis spectroscopy represented all the films absorbed UV well and optical transparency in the visible range. The optical band gap of films changed with Al-doping and bath growth temperatures. The optical band gap decreased after Al-doping at 40°С and increased after Al-doping at 60 and 90°С bath growth temperatures. Which corresponds to the lattice strain value along the c axis. PL spectra were measured at room temperature. All films showed a blue band set at 421 and 440 nm. The peaks were assigned to the surface defects of the samples, such as zinc interstitials and oxygen vacancies. The results showed that Al incorporation is closely related to the bath growth temperature and it also affects the structure, morphological and optical properties of ZnO thin films. Indicate the nanostructured Al-doped ZnO thin films have potential applications in the nanosized blue light source in the display, solar cell window materials and sunscreens.