Synthesis and Characterization of Nanocrystalline ZnO Doped with Al3+ and Ni2+ by a Sol-Gel Method Coupled with Ultrasound Irradiation

Zinc oxide is one of the most important semiconducting metal oxides and one of the most promising n-type materials, but its practical use is limited because of both its high thermal conductivity and its low electrical conductivity. Numerous studies have shown that doping with metals in ZnO structures leads to the modification of the band gap energy. In this work, Al-doped ZnO, Ni-doped ZnO, and undoped ZnO nanocrystalline powders were prepared by a sol&-gel method coupled with ultrasound irradiation, and the results show the influence of Al3+ and Ni2+ ions in the ZnO network. The doping concentrations in ZnO of 0.99 atom % for ZnO&-Al and 0.80 atom % for ZnO&-Ni were obtained by X-ray Fluorescence (XRF). X-ray Diffraction (XRD) and Raman Spectroscopy showed a decreased intensity and broadening of main peaks, indicating metallic ions. The crystallite size of the sample was decreased from 24.5 nm (ZnO) to 22.0 nm (ZnO&-Al) and 21 nm (ZnO&-Ni). The textural and morphological properties were analyzed via Nitrogen Adsorption (BET method) and Field Emission Scanning Electron Microscopy (FESEM).The authors of this paper wish to thank Advanced Nanostructured Materials and Applications Network for its support via Secretaría de Educación Pública (SEP)

อิทธิพลของกรดอะมิโนแอลกอฮอล์ต่อลักษณะทางสัณฐานของผงซิงค์ออกไซด์ที่มีขนาดผลึกในระดับนาโนเมตรและสมบัติเชิงแสง

Thesis (M.Sc., Chemical Studies)--Prince of Songkla University, 200

Synthesis and characterization of zinc titanate nano-crystal powders obtained by mechanical activation

Development of dielectric materials for microwave frequencies is increasing with rapid progress in mobile and satellite communications systems, where zinc titanates have found application due to their semi-conducting and dielectric properties. Mechanical activation by grinding is a well-known method and common part of the powder preparation route in the field of ceramics. The aim of this work is investigation of the influence of experimental conditions for mechanochemical synthesis of zinc orthotitanate. Starting powder mixtures of ZnO and TiO2, in the molar ratio that is in accordance with the stoichiometry of zinc titanate spinel type Zn2TiO4, were mechanically activated using a high-energy planetary ball mill. The process of mechanical activation was performed during different time intervals from 0 to 300 minutes. Microstructure characterization was determined by X-ray diffraction analysis and scanning electron microscopy. Also, the specific surface area (SSA) of powders samples was measured by a nitrogen gas sorption analyzer using the BET method. The very first traces of zinc titanate are detectable after only 5 minutes of activation. The most interesting occurrence during the mechanical method of activation is that we have an almost pure phase after 90 minutes

Controlled Synthesis of Nanomaterials using Reverse Micelles

Monophasic nanosized oxides were synthesised mainly from metal oxalate nanorods obtainedusing the reverse micellar method. This paper focuses on the methodology to obtain importantmetal oxides like tin dioxide, cerium oxide (CeO2 ), zirconia, and zinc oxide. The effect of oxidationstate of the metal ion on the morphology of the oxalates was studied. Nanorods of zinc (II)oxalate (120 nm in dia and 600 nm in length) were obtained while spherical particles of size 4Œ6 nm were obtained for cerium (III) oxalate. The decomposition of these precursors at highertemperature led to the formation of their respective oxides. Mixture of nanorods and nanoparticles of CeO2 was obtained while 3Œ4 nm sized ZrO2 nanoparticles were obtained by thermaldecomposition of zirconium oxalate precursor. The dielectric constant and loss were highly stablewith frequency (at room temperature) for both ceria and zirconia nanoparticles.  ZnO nanoparticles(55 nm sized) were obtained by the decomposition of zinc oxalate nanorods. Three peaks corresponding to free excitonic emission, free-to-bound, and donor-acceptor transitions were observed in the photolumine scence studies at 20 K for ZnO nanoparticles.Defence Science Journal, 2008, 58(4), pp.531-544, DOI:http://dx.doi.org/10.14429/dsj.58.167

Electrochemical Synthesis of Rare Earth Ceramic Oxide Coatings

Rare earth ceramic oxides are used in several applications including, phosphors, gas sensors, fuel cells, catalytic converters, and corrosion protection. These materials exhibit attractive properties such as fracture toughness, stiffness, and high strength-to-weight ratios. Synthesis of rare earth oxides includes a long list of techniques, but electrodeposition is one that has not been used as extensively as other techniques. This chapter discusses in detail the electrochemical synthesis of lanthanum, cerium, and praseodymium oxides. The physical and chemical properties of the electrodeposited oxides are characterized by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, and other techniques. The electrochemical synthesis and post-treatment of other rare earth oxides, such as gadolinium, terbium, samarium, neodymium, europium, and dysprosium oxides are also covered in this chapter. Two main mechanisms of electrodeposition for rare earth oxides are discussed in detail

Al-doped ZnO ceramic sputtering targets based on nanocrystalline powders produced by emulsion detonation synthesis – deposition and application as a transparent conductive oxide material

Transparent conducting oxides (TCOs) have been largely used in the optoelectronic industry due to their singular combination of low electrical resistivity and high optical transmittance. They are usually deposited by magnetron sputtering systems being applied in several devices, specifically thin film solar cells (TFSCs). Sputtering targets are crucial components of the sputtering process, with many of the sputtered films properties dependent on the targets characteristics. The present thesis focuses on the development of high quality conductive Al-doped ZnO (AZO) ceramic sputtering targets based on nanostructured powders produced by emulsion detonation synthesis method (EDSM), and their application as a TCO. In this sense, the influence of several processing parameters was investigated from the targets raw-materials synthesis to the application of sputtered films in optoelectronic devices. The optimized manufactured AZO targets present a final density above 99 % with controlled grain size, an homogeneous microstructure with a well dispersed ZnAl2O4 spinel phase, and electrical resistivities of ~4 × 10-4 Ωcm independently on the Al-doping level among 0.5 and 2.0 wt. % Al2O3. Sintering conditions proved to have a great influence on the properties of the targets and their performance as a sputtering target. It was demonstrated that both deposition process and final properties of the films are related with the targets characteristics, which in turn depends on the initial powder properties. In parallel, the influence of several deposition parameters in the film´s properties sputtered from these targets was investigated. The sputtered AZO TCOs showed electrical properties at room temperature that are superior to simple oxides and comparable to a reference TCO – indium tin oxide (ITO), namely low electrical resistivity of 5.45 × 10-4 Ωcm, high carrier mobility (29.4 cm2V-1s-1), and high charge carrier concentration (3.97 × 1020 cm-3), and also average transmittance in the visible region > 80 %. These superior properties allowed their successful application in different optoelectronic devices

Synthesis and characterization of aluminum doped zinc oxide nanostructures via hydrothermal route

Stable crystalline aluminum doped zinc oxide (AZO) nanopowders were synthesized using hydrothermal treatment processing. Three different aluminum precursors have been used. The Al-precursors were found to affect the morphology of the obtained nanopowders. AZO nanoparticles based on zinc acetate and aluminum nitrate have been prepared with different Al/Zn molar ratios. XRD investigations revealed that all the obtained powders have single phase zincite structure with purity of about 99%. The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. The incorporation of Al in ZnO was confirmed by UV-Vis spectroscopy revealing a blue shift due to Burstein-Moss effect