Utilization of Estremoz marbles sawing sludge in ceramic industry – Preliminary Approach

Portugal is in forefront of world marble production, the marble quarries and processing industries in Estremoz region has an important role in economic life. The amount of waste produced by this activity is massive and cause several problems. The aim of this study is to investigate the suitability and the effect of Estremoz marble sawing sludge in mixtures with clay to ceramic industry. Another main concern is the manufacture of environmental friend ceramics. Plasticity behavior of clay mixtures with 2.5, 5, 10, 15 and 20wt% of marble powder were evaluated. The incorporation of waste reduces the liquid limit and plastic index of pastes. Clay bodies were molded by uniaxial pressure and fired at maximum temperature of 950ºC. The results reveal that the addiction of marble powder increases the water absorption, apparent porosity while the bulk density decreases. Due to their influence in the melted phase an improvement in mechanical strength characteristics was registered, namely in rupture modulus. This preliminary study shows that the use such mixtures are promising in term of ceramics technological properties. Keywords: Estremoz marbles, clay, reuse, ceramics

Anticoagulants utilization in Portugal: are there inequalities?

Communication presented at the 2nd International Congress of CiiEM: Translational Research and Innovation in Human and Health Sciences. 11-13 June 2017, Campus Egas Moniz, Caparica, PortugalN/

Muon implantation experiments in films: obtaining depth-resolved information

Implanted positive muons with low energies (in the range 1-30 keV) are extremely useful local probes in the study of thin films and multi-layer structures. The average muon stopping depth, typically in the order of tens of nanometers, is a function of the muon implantation energy and of the density of the material, but the stopping range extends over a broad region, which is also in the order of tens of nanometers. Therefore, an adequate simulation procedure is required in order to extract the depth dependence of the experimental parameters. Here, we present a method to extract depth-resolved information from the implantation energy dependence of the experimental parameters in a low-energy muon spin spectroscopy experiment. The method and corresponding results are exemplified for a semiconductor film, Cu(In,Ga)Se2, covered with a thin layer of Al2O3, but can be applied to any heterostructure studied with low-energy muons. It is shown that if an effect is present in the experimental data, this method is an important tool to identify its location and depth extent.publishe

Muon diffusion and trapping in chalcopyrite semiconductors

The diffusion parameters of diamagnetic muons in chalcopyrites CuInSe2, CuInS2, CuInTe2, CuGaTe2 and (Ag0.25Cu0.75)InSe2 were obtained by [mu]SR methods. The variations among the different compositions were found to validate the anion-antibonding localization model. The application of a two-state model to the zero-field data revealed muon trapping by defects. The dipolar width at the trap and the number of jumps before trapping were determined. The Cu vacancy is identified as the trapping center in CuInSe2 and the energy depth of the trap has been determined.http://www.sciencedirect.com/science/article/B6TVH-47K37XD-1/1/c6039f1a6212b2c9af977ddf9c54886

Muonium in nano-crystalline II-VI semiconductors

http://www.sciencedirect.com/science/article/B6TVH-4V2NP2J-Y/2/3738c97c2d99528da5d86b486571793

Oxide muonics: A new compendium

A new survey of muonium states brings the total of binary non-magnetic oxides studied to 30, with normal muonium--the interstitially trapped atomic state--found in 15 of these. The number of shallow-donor states of the type known in ZnO now also totals 15, but there are hints of several others. Tantalizingly, the shallow-donor and deep-atomic states are found to coexist in several of the candidate high-permittivity dielectrics. Highly anisotropic states, resembling anomalous muonium in semiconductors and including examples of muonium trapped at oxygen vacancies, complete a spectrum of hyperfine parameters covering five powers of ten. Effective ionization temperatures range from 10 K for shallow to over 1000 K for deep states, with corresponding activation energies between several meV and several eV. The oxide band gap emerges as a parameter controlling the systematics of the deep-to-shallow transition for muonium and, by inference, monatomic hydrogen.http://www.sciencedirect.com/science/article/B6TVH-4HYV078-K/1/89f7584f76f4b62f6fa92e3c5a7d121

Paramagnetic rare earth oxide Nd2O3 investigated by muon spin spectroscopy

In the context of a systematic study of oxide materials with the muon spin spectroscopy amp; 956;SR technique, we report here on an investigation of paramagnetic Nd2O3. The question was whether the magnetism of Nd3 has an influence on the observed signals. In Nd2O3, as in the other oxides, a weakly paramagnetic component is observed besides the pure diamagnetic fraction. The paramagnetic part is assigned to a transient state formed between the initial atomic and the final bound muonium configuration. In addition, a fast relaxing signal amp; 955; amp; 8764; 7 amp; 956;s amp; 8722;1 with 10 to 20 fraction is seen in longitudinal field. Contrary to this general behavior of the oxide materials, in the present magnetic compound, a resonancelike structure is seen in the temperature range around 40 K.We assign it tentatively to a dynamical process related to the population of the first excited Kramers doublet of the Nd3 ion at 2.6 me

Electronic structure of interstitial hydrogen in lutetium oxide from DFT+U calculations and comparison study with μsR spectroscopy

The electronic structure of hydrogen impurity in Lu2O3 was studied by first-principles calculations and muonium spectroscopy. The computational scheme was based on two methods: first, a semi-local functional of conventional density-functional theory (DFT) and secondly a DFT+U approach which accounts for the on-site correlation of the 4f electrons via an effective Hubbardtype interaction. Three different types of stable configurations were found for hydrogen depending upon its charge state. In its negatively-charged and neutral states, hydrogen favors interstitial configurations residing either at the unoccupied sites of the oxygen sublattice or at the empty cube centers surrounded by the lanthanide ions. In contrast, the positively-charged state stabilized only as a bond configuration, where hydrogen binds to oxygen ions. Overall, the results between the two methods agree in the ordering of the formation energies of the different impurity configurations, though within DFT+U the charge-transition (electrical) levels are found at Fermi-level positions with higher energies. Both methods predict that hydrogen is an amphoteric defect in Lu2O3 if the lowest-energy configurations are used to obtain the charge-transition, thermodynamic levels. The calculations of hyperfine constants for the neutral interstitial configurations show a predominantly isotropic hyperfine interaction with two distinct values of 926 and 1061 MHz for the Fermi-contact term originating from the two corresponding interstitial positions of hydrogen in the lattice. These high values are consistent with the muonium spectroscopy measurements which also reveal a strongly isotropic hyperfine signature for the neutral muonium fraction with a magnitude slightly larger (1130 MHz) from the ab-initio results (after scaling with the magnetic moments of the respective nuclei)

Detailed hyperfine structure of muoniated radicals in planar phthalocyanines

http://www.sciencedirect.com/science/article/B6TVH-4V2NP2J-20/2/625b6e64a430f4e722e4eec1de4d54a