In this study new compositions of polyphosphate coacervates were obtained with the ions Ni (2+) and Co (2+). Samples of the glassy systems were prepared with proportions P/M (+2) varying between 0.5 and 10. The qualitative and quantitative description of the first coordination shells of the transition metal were obtained through extended X-ray absorption fine structure spectroscopy (EXAFS) analysis, performed at the Ni (2+) and Co (2+) K-edges. An analysis of the symmetric stretching vibrations of terminal P-O t and bridging P-O b groups performed through Raman spectroscopy revealed the different phases of the coacervation process in terms of bond strengths and corroborates the EXAFS results. The results obtained permitted a detailed structural description of these materials as well as the role played by the metallic ions on the coacervation process.

Molecular dynamics (MD) simulations of binary Cd(x)Pb(1-x)F(2) alloys have been carried out, using a two-body Buckingham interaction potential, leading to a correct description of structural properties as a function of composition and pointing towards an understanding of the eutectic phenomenon. The simulation data can be analyzed in terms of five local fluorine environments Q((n)) (4> or =n> or =0), where n is the number of Pb nearest-neighbor environments. The results suggest a highly nonstatistical population distribution, suggesting an intrinsic phase segregation tendency in the undercooled melt, during the cooling process. This prediction has been tested experimentally for six representative compositions (0.2< or =x< or =0.7) on the basis of high-resolution (19)F solid state NMR data, revealing important similarities between theory and experiment. While the NMR data confirm that the population distribution is, indeed, nonstatistical for all compositions, the results are only found to be consistent with an intrinsic segregation tendency of PbF(2)-rich domains. This tendency manifests itself in substatistical populations of Q((3)) units, resulting in preferred Q((2)) and Q((4)) formations.

Production of oxide glasses containing CuII, CuI and Cu0 nanoparticles by redox process during melting without subsequent thermal treatment.

The vitreous domain was established in the PbF 2 -CdF 2 -B 2 O 3 system from melting and quenching experiments. Er 3+ containing glasses were prepared and glass ceramics were obtained by selected heat-treatments. Lead fluoride was identified (b-PbF 2 ) as the crystalline phase. Structural studies were performed in some glassy and partially crystallized samples by means of X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) measurements. The role of Cd 2+ and Pb 2+ atoms on the glass network formation and also on the crystallization behavior was put forward by these techniques. After crystallization Er 3+ atoms segregated in the crystal phase.

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