Review: Elaboration, structure, and mechanical properties of oxynitride glasses

Abstract

Oxynitride glasses are glasses where threefold coordinated nitrogen atoms substitute for twofold oxygen ones, hence resulting in a larger interatomic crosslinking degree. Such glasses were first observed at the grain boundary in silicon nitride ceramics, where they govern the high-temperature behavior. Later, they were prepared as bulk materials and motivated numerous researches, thanks to their large viscosity, glass transition range, elastic moduli, hardness, and fracture toughness among inorganic and non-metallic glasses. In different chemical systems that were investigated, the synthesis routes and the sources for these exceptional mechanical properties are reviewed. Oxynitride glasses are not easy to process and suffer from the loss of transparency as nitrogen is incorporated over some critical content. Nevertheless, they are attractive "specialty" glasses in various niche areas, thanks to their large refractive index and dielectric constant, improved chemical durability, high softening point, etc., and majorly to their exceptional mechanical properties.

Zirconia‐containing glass‐ceramics: From nucleating agent to primary crystalline phase

“…The introduction of nitrogen and simultaneous incorporation of zirconia into a glass-ceramic has been shown to result in overall improved mechanical properties. 37,38 Stabilization occurs as dopants lower the phase transformation temperatures. As an example, yttria, one of the more popular stabilization agents, is substituted at the zirconia cation creating one oxygen vacancy for every two yttrium ions.…”

“…Specifically, the spherical morphology of tetragonal zirconia precipitated at higher nitrogen contents in MgO–CaO–Al 2 O 3 –SiO 2 oxynitrate glass suppresses the occurrence of the martensitic transformation. The introduction of nitrogen and simultaneous incorporation of zirconia into a glass‐ceramic has been shown to result in overall improved mechanical properties 37,38 …”

Viscous healing of Vickers indentation–induced cracks in glass

“…However, crack healing data for different glasses do not necessarily merge into the same master curve because γ and mechanical properties change with glass composition, and crack geometry varies greatly depending on the crack patterns induced by the Vickers indentation, for example, Palmqvist or Half-penny radial cracks and lateral cracks. [30][31][32][33] Therefore, in the present work, viscous radial crack healing in three different sodium silicate glasses is investigated. To prevent surface crystallization during viscous crack healing, only glasses for which low crystallization tendency could be deducted from literature 26,34,35 were selected.…”

Elucidating photoluminescent properties of Eu‐doped Ca–Al–Si–O(–N) glasses and the local structures of Eu ions

“…Silicon oxynitride glasses are prepared by heating powdered mixtures of the modifier oxide(s) and nitride compounds in crucibles under an Ar or N 2 atmosphere. [14][15][16] Recently, hydrides and metals were utilized for the synthesis of oxynitride glasses with considerably higher nitrogen content than those obtained via conventional melting, owing to their high reactivity with nitrogen upon heating. However, the utilization of metal/metal hydrides reduced the oxides, such as silica in the melts, leading to the formation of metallic microparticles, including silicides, which resulted in decreased transparency and glass blackening.…”

“…Silicon oxynitride glasses are prepared by heating powdered mixtures of the modifier oxide(s) and nitride compounds in crucibles under an Ar or N 2 atmosphere 14–16 . Recently, hydrides and metals were utilized for the synthesis of oxynitride glasses with considerably higher nitrogen content than those obtained via conventional melting, owing to their high reactivity with nitrogen upon heating.…”