The high reactivity of metal alkoxides, common starting reagents in sol-gel-based synthesis routes, generally demands the use of chelating agents in order to avoid fast hydrolysis and also to allow an easier manipulation of intermediates as well as final solutions. Under these conditions, stability issues sometimes can be linked to chelation issues that, therefore, should deserve a proper study suited to the material system of interest and, more specially, when considering the use of sol-gel-based precursors in research, small-scale applications and industry. In this work, we explore the sol-gel-based synthesis route of lead zirconate titanate (Pb(Zr 0⋅53 Ti 0⋅47 )O 3 or PZT 53/47) using acetylacetone-chelated propoxides as intermediate reactants. Our main purpose here is to analyse the influence of the alkoxides:acetylacetone chelation ratio on the time evolution of mean particle size in the resultant organic colloidal dispersion used as PZT precursor. Purposely, we explored three different scenarios for chelation: (i) defective chelation, (ii) optimal chelation and (iii) excessive chelation. The time dependence of mean particle size was recorded by dynamic light scattering (DLS) measurements and aggregation kinetics was then explored by considering a diffusion-limited colloidal aggregations (DLCA) model.
In this paper results of copper removal in ordinario and ethyl alcohol by cementation using an iron rod as a sacrifice anode are presented. Experiments were performed in ordinario containing copper without controlling pH and in an acetate buffer. Concentration before and after cementation were determined by atomic absorption spectroscopy. The highest removal efficiency of Cu (II) in ethyl alcohol and ordinario without buffer occurs at pHs of 4.8 and 3.3 respectively, with 49% removal in both cases. On the other hand, the highest removal percentage of Cu(II) in ethyl alcohol and ordinario at buffered conditions and pHs of 4.9 and 3.0 are 52.1 and 61.1% respectively, the major removal efficiency appears at more acidic pHs because iron has a major facility to oxidize in acidic pH.
In this work we present a comparison of the properties of three tin selenide (SnSe) thin films synthesized by electrodeposition under air or nitrogen atmosphere. The films were synthesized at -0.7 V, -0.8 V, and -0.9 V vs. Ag/AgCl using a fluorine doped tin oxide conductive glass as working electrode, a silver chloride electrode as reference electrode, and a platinum mesh as counter electrode. After the electrodeposition, films were heated at 55°C for 30 minutes in air atmosphere. Films without and with thermal treatment were characterized by UV-Visible Spectroscopy, Atomic Force Microscopy, and Raman Spectroscopy. Analyzing the results, it was found that the optimal conditions for the electrodeposition were at -0.8 V vs Ag/AgCl. Band gap values were in the range from 1.2 to 1.5 eV. Raman spectroscopy revealed characteristic vibrational modes of SnSe and SnSe2 materials. The analysis by Atomic Force Microscopy revealed grain size of 100-700 nm.
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