Surface Chemistry and its Relation to MicroelectronicsCircuits forming part of any electronic device are more efficient, but at the same time the dimension s of theircomponents are reduced constantly and they will soon reach the atomic scale. Each component has to be carefully deposited as a thin film on a surface which, on the atomic scale, is only possible if the chemical reactions involved in the process areunderstood and controlled. This article describes initially the techniques for thin film formation on substrates, emphasizingthe current importance of organometallic compounds during this process. For example, one of these compounds, tetrakis-(dimethylamido)-titanium(IV), Ti[N(CH ) ] , is used, together with ammonia (NH3), for the formation of titanium nitride films. The reaction of both compounds with a silicon surface is investigated, and it is found that in both cases the reacti...

Surface Chemistry and its Relation to MicroelectronicsCircuits forming part of any electronic device are more efficient, but at the same time the dimension s of theircomponents are reduced constantly and they will soon reach the atomic scale. Each component has to be carefully deposited as a thin film on a surface which, on the atomic scale, is only possible if the chemical reactions involved in the process areunderstood and controlled. This article describes initially the techniques for thin film formation on substrates, emphasizingthe current importance of organometallic compounds during this process. For example, one of these compounds, tetrakis-(dimethylamido)-titanium(IV), Ti[N(CH ) ] , is used, together with ammonia (NH3), for the formation of titanium nitride films. The reaction of both compounds with a silicon surface is investigated, and it is found that in both cases the reacti...

Surface Chemistry and its Relation to MicroelectronicsCircuits forming part of any electronic device are more efficient, but at the same time the dimension s of theircomponents are reduced constantly and they will soon reach the atomic scale. Each component has to be carefully deposited as a thin film on a surface which, on the atomic scale, is only possible if the chemical reactions involved in the process areunderstood and controlled. This article describes initially the techniques for thin film formation on substrates, emphasizingthe current importance of organometallic compounds during this process. For example, one of these compounds, tetrakis-(dimethylamido)-titanium(IV), Ti[N(CH ) ] , is used, together with ammonia (NH3), for the formation of titanium nitride films. The reaction of both compounds with a silicon surface is investigated, and it is found that in both cases the reacti...

In spite of the widespread use of the chemical reduction method to obtain silver nanoparticles, the nanoparticle yield is often low due to a required addition of small volumes of diluted metal ions to a solution containing a reducer. Higher yields can be obtained following an alternative method, in which the reducer is added to a greater volume of silver ions in the solution. In this study, protocols for both methods are detailed and compared, using characterization tools such as UV-vis spectrometry, dynamic light scattering (DLS), and zeta potential measurements. By using this alternative method, the amount of silver in the solution is three times greater, and nanoparticles with a narrower size distribution are formed (between 6 and 70 nm in size). In contrast, the regular method produces particles of 3 and 100 nm. Zeta potential measurements indicate that the nanoparticles synthesized ...

Understanding the changes of a mineral during ore processing is of capital importance for the development of strategies aimed at increasing the efficiency of metal extraction. This task is often difficult due to the variability of the ore in terms of composition, mineralogy and texture. In particular, surface processes such as metal re-adsorption (preg-robbing) on specific minerals are difficult to evaluate, even though they may be of importance as the re-adsorbed material can be blocking the valuable mineral and negatively affect the extraction process. Here, we show a simple yet powerful approach, through which surface processes in individual minerals are identified by combining polarization microscopy (MP) and X-ray photoelectron spectroscopy (XPS). Taking as an example a silver-containing polymetallic sulfide ore from the Peruvian central Andes (pyrite-based with small amounts of gal...

Understanding the changes of a mineral during ore processing is of capital importance for the development of strategies aimed at increasing the efficiency of metal extraction. This task is often difficult due to the variability of the ore in terms of composition, mineralogy and texture. In particular, surface processes such as metal re-adsorption (preg-robbing) on specific minerals are difficult to evaluate, even though they may be of importance as the re-adsorbed material can be blocking the valuable mineral and negatively affect the extraction process. Here, we show a simple yet powerful approach, through which surface processes in individual minerals are identified by combining polarization microscopy (MP) and X-ray photoelectron spectroscopy (XPS). Taking as an example a silver-containing polymetallic sulfide ore from the Peruvian central Andes (pyrite-based with small amounts of gal...

The presence of copper in ores containing noble metals results in a high consumption of cyanide during leaching, which is undesirable from economic and environmental standpoints. Substantial previous work targets copper-gold ores, but the present study focuses on a copper-silver ore, which will be leached following acidic pretreatment (sulfuric acid at pH 1) to assess the effect of copper in cyanide consumption and silver extraction. The ore is mainly composed of hematite/goethite and silicates, with copper (0.15%) and silver (250 ppm) mostly present as sulfides and sulfosalts. The acidic pretreatment dissolves 18% of the copper content, which in turn decreases the cyanide consumption from 7 to 3 kg NaCN/ton in a five-hour leaching. Mineralogical changes, followed by polarization microscopy, are only minimal and restricted to iron oxides, while silicates and sulfides remain unchanged. Ho...