Complex Oxynitrides

Hardness of Oxynitride Glasses: Topological Origin

“…10,11 This increase of the degree of the network cross-linking, along with the more covalent nature of the nitrogen-modifier cation bonding, contracts 12 and rigidifies the glass network. 13 While the Si−O single bond strength (∼452 kJ/mol) is somewhat higher than that of the Si−N bond (355 kJ/mol), the increase in local bond density results in a net increase of local bond energy, what is best visible in the associated increase in Young's modulus.…”

“…Oxynitride glasses, in which the 2-fold coordinated oxygen atoms have been partially substituted by 3-fold coordinated nitrogen atoms, are of interest in this respect. , These glassy materials were first observed as grain-boundary phases in silicon-nitride based ceramics; now their potential applications include use as passive coatings on electronic substrates, high-speed hard disk drive substrates, bioglasses, solid-state lithium batteries, improved ballistic resistance for transparent armor materials, and host material for LED phosphors . Partial exchange of the 2-fold coordinated oxygen atoms with the 3-fold coordinated nitrogen atoms results in a greater degree of cross-linking of the anion sub-network of the glass. , This increase of the degree of the network cross-linking, along with the more covalent nature of the nitrogen-modifier cation bonding, contracts and rigidifies the glass network . While the Si–O single bond strength (∼452 kJ/mol) is somewhat higher than that of the Si–N bond (355 kJ/mol), the increase in local bond density results in a net increase of local bond energy, what is best visible in the associated increase in Young’s modulus.…”

Composition–structure–property relationships of transparent Ca–Al–Si–O–N oxynitride glasses: The roles of nitrogen and aluminum

“…3,4,15 Hence, the herein observed concurrently enhanced glass properties with the Al and N contents of the glasses must originate from the AlO 4 tetrahedra, despite that Al-O bonds are expected to be weaker than those of Si-O/N. 3,17 Our somewhat puzzling findings demand further research to shed light on the precise structural role of Al for governing mechanical and thermal properties of M-Al-Si-O-N glasses. We suggest that although such a road map may benefit from employing alkaline-earth-based systems, optimized mechanical properties are most likely offered by RE-Al-Si-O-N glasses rich in N and Al but devoid of NBO species.…”

“…Cooling of the system then results in amorphous intergranular components, the composition and structure of which strongly influence the material properties 6–8 . The experimental complications of selectively probing these grain boundary phases triggered research in the early 1970s toward the production and characterization of silicate‐based oxynitride glasses in bulk form to improve the understanding of their structures and composition–property relationships 3–17 …”

“…[1][2][3][4][5] The preparation of crystalline Si-(Al)-O-N phases typically characterization of silicate-based oxynitride glasses in bulk form to improve the understanding of their structures and composition-property relationships. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Following the pioneering developments of oxynitride glasses, 6,7,9,12,18,19 a large number of studies are reported on the glass formation of silicate-based oxynitride glasses incorporating glass-network modifiers, such as various alkaline-earth and RE metal cations. [3][4][5] The glass preparation is facilitated by including alumina, which besides lowering the melt temperature also expands the composition region that yields homogeneous amorphous phases by suppressing the liquid immiscibility zones.…”