Assessment of dissolution techniques for the analysis of ceramic samples by plasma spectrometry

In this study, 13 ceramic samples were subjected to dissolution using three different procedures: (a) acid attack in open PTFE vessels with a mixture of HF-HClO4, (b) fusion of the sample with lithium metaborate and (c) microwave digestion in PTFE bombs. The samples used in the study had been previously analyzed by neutron activation analysis (NAA), X-ray fluorescence (XRF) and X-ray diffraction (XRD) and they cover a wide range of ceramics fired in different atmospheres and temperatures as well as different mineralogical and chemical compositions. The effectiveness of each procedure is evaluated in terms of its ability to dissolve the various mineralogical phases of the samples, of the number of elements that can be determined and of the time needed for the whole scheme of analysis to be completed.

Microscopic, chemical, and molecular-biological investigation of the decayed medieval stained window glasses of two Catalonian churches

We investigated the decayed historical church window glasses of two Catalonian churches, both under Mediterranean climate. Glass surfaces were studied by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). Their chemical composition was determined by avelength-dispersive spectrometry (WDS) microprobe analysis. The biodiversity was investigated by molecular methods: DNA extraction from glass, amplification by PCR targeting the16S rRNA and ITS regions, and fingerprint analyses by denaturing gradient gel electrophoresis (DGGE). Clone libraries containing either PCR fragments of the bacterial 16S rDNA or the fungal ITS regions were screened by DGGE. Clone inserts were sequenced and compared with the EMBL database.

Thin Film Transistors obtained by Hot-Wire CVD

Hydrogenated microcrystalline silicon films obtained at low temperature (150-280°C) by hot wire chemical vapour deposition at two different process pressures were measured by Raman spectroscopy, X-ray diffraction (XRD) spectroscopy and photothermal deflection spectroscopy (PDS). A crystalline fraction >90% with a subgap optical absortion 10 cm -1 at 0.8 eV were obtained in films deposited at growth rates >0.8 nm/s. These films were incorporated in n-channel thin film transistors and their electrical properties were measured. The saturation mobility was 0.72 ± 0.05 cm 2/ V s and the threshold voltage around 0.2 eV. The dependence of their conductance activation energies on gate voltages were related to the properties of the material.

Structure of a-Si:H/a-Si1-xCx:H multilayers deposited in a reactor with automated substrate holder

This paper deals with the structural properties of a-Si:H/a-Si1-xCx: H multilayers deposited by glow-discharge decomposition of SiH4 and SiH4 and CH4 mixtures. The main feature of the rf plasma reactor is an automated substrate holder. The plasma stabilization time and its influence on the multilayer obtained is discussed. A series of a-Si:H/a-Si1-xCx: H multilayers has been deposited and characterized by secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). No asymmetry between the two types of interface has been observed. The results show that the multilayers present a very good periodicity and low roughness. The difficulty of determining the abruptness of the multilayer at the nanometer scale is discussed.

Síntesi de pólvores del superconductor GdBa2Cu3O7 a partir de dissolucions precursores de nitrats

Estudi de l’obtenció de les les pólvores del compost superconductor GdBa2Cu3O7 mitjançant la utilització de diferents mètodes partint de solucions aquoses de nitrat estabilitzades amb PEG, com son apartir del reactor Kjeldhal o a partir d’un assecatge ràpid damunt una placa calefactora.En el procés d’obtenció d’aquestes pólvores es vol fer una caracterització dels productesinicials, intermedis i finals que s’aniran obtenint durant les diferents etapes. Aquest estudi esfarà mitjançant varis tipus d’anàlisi, com la difracció de raig X (XRD), l’espectroscòpiainfraroja (IR) o la termogravimetria (TG).Finalment, també es comprovarà si els nitrats i el PEG que formen la solució aquosa espoden assecar en forma de capa, i si posteriorment, és possible la seva descomposició percombustió