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Metaphosphate glasses such as LiPO3 and NaPO3 are known to incorporate nitrogen in the molten state under NH3 flow to form (Li/Na)PON glasses through the reaction: (Li/Na)PO3 + xNH3 → (Li/Na)PO3−(3x/2)Nx + (3x/2)H2O, by partially replacing two‐coordinated oxygen with two‐ and three‐coordinated nitrogen. After nitridation, the glasses exhibit improved properties such as increased working range, chemical durability, and ionic conductivity. In this study, LiPO3 and NaPO3 glasses were prepared by the conventional melting and casting method and used as base glasses for the ammonolysis procedure. The nitridation processes were carried out by remelting the base glasses at temperatures up to 780°C, under a constant NH3 flow. The effects on the nitrogen content in the resulting (Li/Na)PON glasses caused by different processing times and masses of powder and/or bulk materials were investigated. Nitridation was successfully confirmed by CNHS chemical analyses, Raman spectroscopy, and Differential Scanning Calorimetry. Mass loss measurements after the ammonolysis process and Raman spectroscopy were used to quantify the nitrogen content into the glass structure. A new approach using a specific Raman normalization, (P–N<)/(O–P–O)sym, has been demonstrated as a reliable, simple, and fast way to determine the amounts of N incorporated to metaphosphate glass structures.

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2008Fluoride-modified electrical properties of lead borate glasses and electrochemically induced crystallization in the glassy state JOURNAL OF APPLIED PHYSICS, v.103, n.4, 2008 http://producao.usp Lead fluoroborate glasses were prepared by the melt-quenching technique and characterized in terms of ͑micro͒structural and electrical properties. The study was conducted on as prepared as well as temperature-and/or electric field-treated glass samples. The results show that, in the as-prepared glassy-state materials, electrical conductivity improved with increasing the PbF 2 glass content. This result involves both an increase of the fluoride charge carrier density and, especially, a decrease of the activation energy from a glass structure expansion improving charge carrier mobility. Moreover, for the electric field-treated glass samples, surface crystallization was observed even below the glass transition temperature. As previously proposed in literature, and shown here, the occurrence of this phenomenon arose from an electrochemically induced redox reaction at the electrodes, followed by crystallite nucleation. Once nucleated, growth of ␤-PbF 2 crystallites, with the indication of incorporating reduced lead ions ͑Pb + ͒, was both ͑micro͒structurally and electrically detectable and analyzed. The overall crystallization-associated features observed here adapt well with the floppy-rigid model that has been proposed to further complete the original continuous-random-network model by Zachariasen for closely addressing not only glasses' structure but also crystallization mechanism. Finally, the crystallization-modified kinetic picture of the glasses' electrical properties, through application of polarization/depolarization measurements originally combined with impedance spectroscopy, was extensively explored.