Search results for " SOLID"

Emissions of Greenhouse Gases and Climate Politics in the Latvian Waste Sector

2015

According IPCC guidelines for determination of greenhouse gases in waste management (IPCC 2006) the quantity of greenhouse gases must be determined for the emissions of CO2, CH4, N2O for such treatment activities: disposal of solid waste, biological treatment of solid waste and incineration and open burning of waste. Presented report reviles the current situation of this field in Latvia and conclusions on its minimization actions. The data received from Latvian environmental data bases shows that the quantity of disposed unsorted municipal waste is rising and created sanitary landfill system with anaerobic digestion of bio mas (the content of it in the disposed waste reaches 40–50 %) is pro…

MISURA DELLA CONCENTRAZIONE DI SOLIDI PARTICELLARI IN SISTEMI SOLIDO-LIQUIDO AGITATI MEDIANTE LASER PULSATO E ANALISI DI IMMAGINI

2008

Development of LIBS for online analysis of solid nuclear materials

2015

With the objective to implement a fast, online analysis technique for control of solid metal nuclear materials, laser-induced breakdown spectroscopy (LIBS) technique is developed for quantitative analysis in uranium and plutonium. Since these matrices have a very dense emission spectrum in the UV-Visible range, the Vacuum Ultra-Violet (VUV) spectral range, less rich in lines, is explored. The aim of this thesis is to perform the analytical development of VUV-LIBS for quantitative analysis between 500 and 5000 ppm with an uncertainty of 3%. For that purpose, four steps were defined. First, for practical and safety reasons, it is generally better to perform experiments on surrogate materials.…

Amorphous TiO2 in LP-OMCVD TiNxOy thin films revealed by XPS

2001

Abstract TiN(O)–TiO 2 thin films were prepared on Si(1 0 0) by the low pressure organo metallic chemical vapor deposition (LP-OMCVD) method, using ammonia and titanium isopropoxide as precursors. In order to complete previous characterizations, an Ar + bombardment/XPS coupled study was carried out. This method is based on the fact that the behavior of a compound towards an ion bombardment is a function of its composition. In particular, Ar + bombardment of TiO 2 (whatever its form) leads to a preferential sputtering of oxygen atoms with subsequent reduction of titanium and formation of Ti 3+ and Ti 2+ easily detectable by XPS from a significant broadening of the Ti 2p lines. In the opposite…

Amorphous, nanocrystalline and crystalline calcium carbonates in biological materials

2010

Raman spectroscopy is a powerful tool in identifying different calcium carbonate polymorphs. Here, the method is applied to cultured pearls from freshwater (genus Hyriopsis) and marine bivalve species (Pinctada maxima) as well as to shells of Diplodon chilensis patagonicus bivalves. Raman spectra for vaterite, detected for the first time in an adult shell, and amorphous calcium carbonate (ACC) are discussed. Results for ACC are compared with those of synthetically produced ACC and with the Raman spectroscopic features of stable biogenic ACC from the crustacean Porcellio scaber. Decomposition of the most intense signal of all calcium carbonate polymorphs—the ν1 symmetric stretching mode of t…

Effect of the Mo atom flow on the molybdenum growth on TiO2 (110) surface

2004

Abstract Molybdenum has been deposited at room temperature on stoichiometric TiO 2 (1 1 0) surfaces with two deposition rates: 0.1 equivalent monolayer (eqML) and 1.5 eqML min −1 . X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy studies clearly reveal an effect of the deposition rate upon the growth mode and the interfacial reaction. Indeed, whereas a strong interfacial reaction between Mo and TiO 2 involves a Stranski–Krastanov growth mode with the formation of amorphous molybdenum oxide monolayers for the lowest deposition rate, no reaction can be observed for the highest deposition rate. Moreover in this latter case, the growth mode seems to be a 3D …

A structural investigation of titanium dioxide photocatalysts

1991

Abstract A study of the structure and the morphology of a titanium dioxide photocatalyst (Degussa P25) reveals multiphasic material consisting of an amorphous state, together with the crystalline phases anatase and rutile in the approximate proportions 80 20 . Transmission electron microscopy provides evidence that some individual particles are a mixture of the amorphous state with either the anatase phase or with the rutile phase, and that some particles, which are mostly anatase, are covered by a thin overlayer of rutile which manifests its presence by the appearance of Moire fringes. The photocatalytic activity of this form of titanium dioxide is reported as being greater than the activi…

The influence of the anatase nanoparticles boundaries on the titania activity performance

2014

Metal oxides structures, formed by ordered self-assembling of crystalline nanoparticles aggregates, are attracting growing attention in fields such as catalysis or solar cells. The properties of these structures are influenced not only by their morphology and nanoparticles composition but also by the assembled particles boundaries. In order to determine the influence of these boundaries on the structures properties, the present investigation has been devoted to study the characteristics of anatase nanoparticles boundaries in titania aggregates prepared by TiCl4 hydrolysis at low temperature. Proton magic angle spinning nuclear magnetic resonance and high resolution transmission electron mic…

Reactive direct current magnetron sputtered TiO2 thin films with amorphous to crystalline structures.

2008

International audience; TiO2 thin films were deposited on soda–lime glass substrates by reactive direct current magnetron sputtering in a mixture of pure argon and oxygen. The influence of both the deposition time, td, and the post-annealing treatments on the films morphology, composition and structure was analyzed by scanning electron microscopy, ellipsometry, X-ray photoelectrons spectroscopy, X-ray diffraction (XRD) and Raman spectroscopy. Amorphous TiO2 was obtained for the shortest deposition time, td=15 min. Increasing td up to 30 min, poorly crystallized anatase and rutile phases were formed together with amorphous TiO2, as was revealed by complementary XRD patterns and Raman spectra…

Anatase nanoparticles boundaries resulting from titanium tetrachloride hydrolysis

2017

An important factor that governs solar energy transformation into electrical or chemical energy, when using nanoparticles-based devices, is the spatial location of traps limiting electron transport. Evidences have been presented indicating that the electron diffusion is strongly influenced by nanoparticle boundaries, whose characteristics depend on the particles preparation. In the present work we have studied the role of hydrated excess proton structures in the formation of anatase nanoparticles boundaries in samples prepared by TiCl4 hydrolysis at low temperature and strong acidic conditions. The samples, constituted by anatase nanocrystals but, mainly, by amorphous titania, are studied b…