2004, Muñoz, F., Pascual, L., Durán, A., Montagne, L., Berjoan, R., Marchand, R.

The development ofmicroelectronics towards lower processing temperatures needs a parallel development of lower temperatures sealing materials. Due to particular thermal properties, such as high thermal expansion coefficient, α ,and low glass transition and dilatometric softening temperatures, Tg and Ts, phosphate glasses are of interest for application as low-temperature sealing glasses. An efficient method to significantly improve the accompanying poor chemical durability of these glasses is a partial anionic Substitution of nitrogen(Ν³¯)for oxygen (O²¯), which induces crosslinking between chains through covalent P-N bonds. New Li_(0.25)Na_(0.25)Pb_(0.25)PO_(3-3x/2)N_x phosphorus oxynitride glass compositions (0 < X ≤ 0.69) have been elaborated by thermal treatment of corresponding oxide base glasses in an hydrous ammonia atmosphere, at temperatures ranging from 600 to 750°C and for times up to 30h. The introduction of nitrogenin the glass network induces also a linear decrease in α, and a linear increase in Tg andTs, however without changing them too much. Α structural study has been carried out using nuclearmagnetic resonance and x-ray photoelectron spectroscopies. ³¹P MAS NMR shows that the glass network is built up of PO₄, PO₃N and PO₂N₂ tetrahedral units. PO₄-PO₄, PO₄-PO₃N and PO₃N-PO₂N₂ connections, evidenced by ³¹P-MAS NMR, are homogeneously distributed within the glass network. XPS at the Nis core level indicates that nitrogen atoms substitute for both bridging and non-bridging oxygen atoms, as two-coordinated -N= (Nd) or three-coordinated -N< (Nt) species. Α higher amount of Nd-type than Nt-type atoms is found for the highest nitrogen contents. ²³Na and ²⁰⁷Pb NMR results show that the nitrogen-oxygen substitution does not affect oxygen atoms coordinating modifier cations. The role played by lead in these "LINaPbPON" glasses is deduced from a comparison with the nitridation study in "LINaPON" and "NaPON" systems. The presence of Pb²⁺ cations has clearly an influence on the nitridation mechanism. They behave essentially as modifier cations, however they show with the nitrogen enrichment an increased network forming character.

2004, Antoni, E., Montagne, L., Tricot, G., Palavit, G., Bernard, J. L.

[no abstract available]

2004, Palavit, G., Bekaert, E., Quoirin, G., Montagne, L.

Lead phosphate was introduced into an aluminosilicate glass for the immobilisation of the toxic heavy metal. Weight loss measurement and elemental analyses indicate that no loss occurs during the melting at 1300°C. ³¹P and ²⁹Si MAS-NMR indicate that the lead phosphate is dissociated into the aluminosilicate glass, and that the polymerisation of the silicate network increases.