Preparation, structural characterization, semiconductor and photoluminescent properties of zinc oxide nanoparticles in a phosphonium-based ionic liquid

A convenient microwave method in preparation of zinc oxide nanoparticles (ZnONPs) using an ionic liquid, trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide, [P-66614][NTf2], as a green solvent is described in this paper. To the best of our knowledge, there is no report for synthesizing any nanoparticle using this ionic liquid. Trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide has low interface tension and thus it can enhance the nucleation rate, which is favorable to the formation of smaller ZnONPs. The fabricated ZnONPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis spectroscopy. The XRD pattern reveals that the ZnONPs have hexagonal wurtzite structure. The strong intensity and narrow width of ZnO diffraction peaks indicate that the resulting nanoparticles are of high crystallinity. The synthesized ZnONPs show direct band gap of 3.43 eV. The UV-vis absorption spectrum of ZnONPs dispersed in ethylene glycol at room temperature revealed a blue-shifted onset of absorption. (C) 2011 Elsevier Ltd. All rights reserved.

Synthesis of Zinc oxide nanorods via conductive polymeric template and its potential application in hybrid solar cells.

Tesis (Doctorado en Ciencias con orientación en Química de los Materiales) UANL, 2014.

Spray Pyrolysed Zinc Oxide Thin Films : Effects of Doping and Ion Beam Irradiation

In recent years scientists have made rapid and significant advances in the field of semiconductor physics. One of the most important fields of current interest in materials science is the fundamental aspects and applications of conducting transparent oxide thin films (TCO). The characteristic properties of such coatings are low electrical resistivity and high transparency in the visible region. The first semitransparent and electrically conducting CdO film was reported as early as in 1907 [1]. Though early work on these films was performed out of purely scientific interest, substantial technological advances in such films were made after 1940. The technological interest in the study of transparent semiconducting films was generated mainly due to the potential applications of these materials both in industry and research. Such films demonstrated their utility as transparent electrical heaters for windscreens in the aircraft industry. However, during the last decade, these conducting transparent films have been widely used in a variety of other applications such as gas sensors [2], solar cells [3], heat reflectors [4], light emitting devices [5] and laser damage resistant coatings in high power laser technology [6]. Just a few materials dominate the current TCO industry and the two dominant markets for TCO’s are in architectural applications and flat panel displays. The architectural use of TCO is for energy efficient windows. Fluorine doped tin oxide (FTO), deposited using a pyrolysis process is the TCO usually finds maximum application. SnO2 also finds application ad coatings for windows, which are efficient in preventing radiative heat loss, due to low emissivity (0.16). Pyrolitic tin oxide is used in PV modules, touch screens and plasma displays. However indium tin oxide (ITO) is mostly used in the majority of flat panel display (FPD) applications. In FPDs, the basic function of ITO is as transparent electrodes. The volume of FPD’s produced, and hence the volume of ITO coatings produced, continues to grow rapidly. But the current increase in the cost of indium and the scarcity of this material created the difficulty in obtaining low cost TCOs. Hence search for alternative TCO materials has been a topic of active research for the last few decades. This resulted in the development of binary materials like ZnO, SnO2, CdO and ternary materials like II Zn2SnO4, CdSb2O6:Y, ZnSO3, GaInO3 etc. The use of multicomponent oxide materials makes it possible to have TCO films suitable for specialized applications because by altering their chemical compositions, one can control the electrical, optical, chemical and physical properties. But the advantages of using binary materials are the easiness to control the chemical compositions and depositions conditions. Recently, there were reports claiming the deposition of CdO:In films with a resistivity of the order of 10-5 ohm cm for flat panel displays and solar cells. However they find limited use because of Cd-Toxicity. In this regard, ZnO films developed in 1980s, are very useful as these use Zn, an abundant, inexpensive and nontoxic material. Resistivity of this material is still not very low, but can be reduced through doping with group-III elements like In, Al or Ga or with F [6]. Hence there is a great interest in ZnO as an alternative of ITO. In the present study, we prepared and characterized transparent and conducting ZnO thin films, using a cost effective technique viz Chemical Spray Pyrolysis (CSP). This technique is also suitable for large area film deposition. It involves spraying a solution, (usually aqueous) containing soluble salts of the constituents of the desired compound, onto a heated substrate.

The metabolic impact of zinc oxide on porcine intestinal cells and enterotoxigenic Escherichia coli K88

Pharmacological levels of zinc oxide (ZnO) incorporated into the post-weaning piglet diet reduce the incidence of diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) K88. The mechanism for this is not understood. Here, Intestinal Porcine Epithelial Cells (IPEC) J2 were used as an in vitro model of the porcine intestine. ZnO reduced IPEC J2 viability at concentrations >= 200 mu M, and ETEC adhesion to the host cell was unaffected by ZnO. Characterisation of the metabolism of IPEC J2 cells and ETEC established the effects of ZnO treatment on the metabolic profile of both. Although 100 mu M ZnO did not inhibit growth of either host or pathogen in fully supplemented media, metabolic profiles were significantly altered. Glucose and mannose were essential energy sources for IPEC J2 cells in the presence of ZnO, as the ability to utilise other sources was compromised. The increase in specificity of requirements to support respiration in ETEC was more pronounced, in particular the need for cysteine as a nitrogen source. These findings indicate that ZnO impacts on both host cell and pathogen metabolism and may provide insight into the mechanism for diarrhoea reduction. (C) 2010 Elsevier B.V. All rights reserved.

Luminescent properties and lattice defects correlation on zinc oxide

The ZnO luminescent properties are strongly influenced by the preparation method and they are principally related to electronic and crystalline structures. This work reports about the correlation among luminescence properties of ZnO, obtained from zinc hydroxycarbonate, and crystalline lattice defects, microstrain, as function of thermal treatment. The crystallite size increase and the qualitative microstrain, obtained by Williamson-Hall plots, decrease as function of temperature. The evolution of electronic defects is analyzed by luminescence spectroscopy based on energy of the electronic transitions. From excitation spectrum, it is verified two bands around 377 nm and 405 nm attributed to the transitions between valence-conduction bands and valence band to interstitial zinc level, respectively. The emission spectra of sample treated at 600 degreesC shows large band at 670 nm. However, the green emission around 530 nm is observed for samples treated at 900 degreesC. The intensities of excitation and emission bands are associated with the increase of the electronic defects that depend on the strain lattice decrease. The lowest strain lattice results on the best green luminescent properties of zinc oxide. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Electroluminescence of zinc oxide thin-films prepared via polymeric precursor and via sol-gel methods

Zinc oxide (ZnO) is an electroluminescent (EL) material that can emit light in different regions of electromagnetic spectrum when electrically excited. Since ZnO is chemically stable, inexpensive and environmentally friendly material, its EL property can be useful to construct solid-state lamps for illumination or as UV emitter. We present here two wet chemical methods to prepare ZnO thin-films: the Pechini method and the sol-gel method, with both methods resulting in crystalline and transparent films with transmittance > 85% at 550 nm. These films were used to make thin-film electroluminescent devices (TFELD) using two different insulator layers: lithium fluoride (LiF) or silica (SiO2). All the devices exhibit at least two wide emission bands in the visible range centered at 420 nm and at 380 nm attributed to the electronic defects in the ZnO optical band gap. Besides these two bands, the device using SiO2 and ZnO film obtained via sol-gel exhibits an additional band in the UV range centered at 350 nm which can be attributed to excitonic emission. These emission bands of ZnO can transfer their energy when a proper dopant is present. For the devices produced the voltage-current characteristics were measured in a specific range of applied voltage. (C) 2007 Elsevier B.V. All rights reserved.

Low voltage electroluminescence of terbium- and thulium-doped zinc oxide films

Strong interest in developing technology for visual information. stimulates research for thin film electroluminescent devices. Here, for the first time, we report that thulium- and terbium-doped zinc-oxide films are suitable for electroluminescence applications. Two different devices were assembled as lTO/LiF/ZnO:RE/LiF/Al or ITO/SiO2/ZnO:RE/SiO2/Al, where ZnO:RE is a film of zinc oxide containing 10 at% of Tb3+ or Tm3+. Electroluminescence spectra show that besides a broad emission band with maximum around 650 nm assigned to ZnO, also emission lines from Tb3+ at 484 nm (D-5(4) -> F-7(6)), 543 nm (D-5(4) -> F-7(6)), and 589 nm (D-5(4) -> F-7(4)), or from Tm3+ at 478 nm ((1)G(4) -> H-3(6)), and 511 mn (D-1(2) -> H-3(5)) were detected. Intensity of emission as function of applied voltage and current-voltage characteristic are shown and discussed. (c) 2005 Elsevier B.V. All rights reserved.

Wettability and photodegradation activity of sol-gel dip-coated zinc oxide films

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Study of crystallite size and strain as a function of morphological evolution in zinc oxide powder obtained from hydroxycarbonate precursor

In this work, zinc oxide samples were obtained from hydroxycarbonate by thermal decomposition at 300°C. Zinc hydroxycarbonate samples were produced by homogeneous precipitation over different periods of time. The method used to obtain zinc oxide produces different morphologies as a function of the precursor precipitation time. Among the obtained particle shapes were porous spherical aggregates, spherulitic needle aggregates, and single acicular particles. This work investigated spherulitic needle-aggregate formation and the correlation among morphology, domain size, and microstrain. Transmission electron microscopy data revealed that the acicular particles that form the spherulitic needle aggregates consist of nanometer crystallites. Apparent crystallite size and microstrain in the directions perpendicular to (h00), (h0l), (hk0), and (00l) planes were invariable as a function of precursor precipitation time. From the results, it was possible to conclude that the precursor precipitation period directly influenced the morphology of the zinc oxide but did not influence average crystallite size and microstrain for ZnO samples. Therefore, using this route, it was possible to prepare zinc oxide with different morphologies without microstructural alterations. © 2001 International Centre for Diffraction Data.

Use of nicarbazin, salinomycin and zinc oxide as alternative molting methods for commercial laying hens

An experiment was carried out to evaluate the performance, egg quality and morphometry of the reproductive tract, liver, pancreas and tongue of laying hens submitted to different molting methods. Two hundred and eighty eight 72-week-old Isa brown layers were distributed according to a completely randomized design with six treatments (molting methods) and six replicates of eight birds each. Layers were fed diets containing 3000 ppm zinc oxide, 60 ppm or 120 ppm nicarbazin, 30 ppm or 60 ppm salinomycin, or were submitted to feed fasting. Data were submitted to analysis of variance and means were compared by the test of Tukey at 5% probability level. Molting methods alternative to feed fasting were effective to induce molting in layer and provided good performance results in the second laying cycle.

Laser emission of a Nd-doped mixed tellurite and zinc oxide glass

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of zirconium oxide and zinc oxide nanoparticles on physicochemical properties and antibiofilm activity of a calcium silicate-based material

The aim of the present study was to evaluate the antibiofilm activity against Enterococcus faecalis, compressive strength. and radiopacity of Portland cement (PC) added to zirconium oxide (ZrO2), as radiopacifier, with or without nanoparticulated zinc oxide (ZnO).The following experimental materials were evaluated: PC, PC + ZrO2, PC + ZrO2 + ZnO (5%), and PC + ZrO2 + ZnO (10%). Antibiofilm activity was analyzed by using direct contact test (DCT) on Enterococcus faecalis biofilm, for 5 h or 15 h. The analysis was conducted by using the number of colony-forming units (CFU/mL). The compressive strength was performed in a mechanical testing machine. For the radiopacity tests, the specimens were radiographed together with an aluminium stepwedge. The results were submitted to ANOVA and Tukey tests, with level of significance at 5%. The results showed that all materials presented similar antibiofilm activity (

Use of nanoparticulate zinc oxide as intracanal medication in endodontics: pH and antimicrobial activity

The aim of this study was to evaluate the pH and antimicrobial activity of micro or nanoparticulate zinc oxide (ZnO) pastes with or without calcium hydroxide (CH). The following medications were evaluated: microparticulate ZnO + polyethylene glycol (PEG) 400; nanoparticulate ZnO + PEG 400; PEG 400; CH + microparticulate ZnO + PEG 400 and CH + nanoparticulate ZnO + PEG 400. The pH was assessed between 12 hours and 28 days, using a digital pH meter. The antimicrobial activity against Enterococcus faecalis (ATCC-9212), Candida albicans (ATCC-10231), Pseudomonas aeruginosa (ATCC-27853), Staphylococcus aureus (ATCC-6538) and Kocuria rhizophila (ATCC-9341) was determined in triplicate using agar diffusion test. The results were submitted to Kruskal-Wallis/Dunn and ANOVA/Tukey tests with 5% significance. The highest pH values were found for CH+ZnO, with higher values for nanoparticulate ZnO after 12 hours and 21 days (p<0.05). CH+ZnO medication promoted higher growth inhibition against P. aeruginosa and lower against E. faecalis. Calcium hydroxide pastes have higher pH and antimicrobial activity when associated with either micro- or nanoparticulate zinc oxide.