La-Si-O-N glasses

Composition–property relationships of the La2O3–Al2O3–SiO2 glass system

“…The nitrogen atoms substitute for oxygen atoms in the glass network and the higher negative charge of N 3À is balanced by an increased number of positive modifier ions. Density, glass transition temperature, hardness, elastic moduli and refractive index have been observed to increase for increasing nitrogen content [28,49,50,[56][57][58][59][60][61][63][64][65]67,68]. These changes have been attributed to an enhanced glass network cross-linking from the presence of three-coordinated nitrogen atoms [49,50,[57][58][59][60][61][63][64][65].…”

“…RE aluminosilicate glasses have several similarities with RE-Si-(Al)-O-N oxynitride glasses [28,49,50,[56][57][58][59][60][61][62][63][64][65][66][67]. Both display high values of the Poisson's ratio, e.g., %0.30 for La aluminosilicate glasses [53] and 0.27-0.36 for Ca-Si-O-N glasses [56].…”

“…The effects on physical properties from nitrogen and modifier elements have been reported to be additive and independent [65,68], although the variations in physical properties are believed to display a larger dependence on the nitrogen content than on the amount of the modifier cations. Nevertheless, a separation of the effects is obscured as an increase in the nitrogen content is generally correlated with a simultaneous increase in the modifier content [28,56,66,67]. For instance, in the case of nitrogen-rich La-Si-O-N glasses [28,66,67], high hardness values are observed even for compositions associated with (very) high values r P 3, which necessarily imply significantly depolymerized networks.…”

Hardness and refractive index of Ca–Si–O–N glasses

“…Largely due to the feasibility to produce refractory silicon nitride based ceramics containing oxynitride glasses as grain-boundary phases, a number of investigations have been carried out on oxynitride glass formation and properties [7][8][9]. Oxynitride glasses have since been prepared in systems including Y-Si-Al-O-N [10][11][12][13][14], Mg-Si-O-N [15,16], La-Si-O-N [17][18][19], Na-Ca-Si-O-N [20], Na-B-Si-O-N [21], Ca-Si-Al-O-N [22][23][24], Mg-Si-Al-O-N [8,24], Li-B-O-N [25], Na-B-O-N [25] and K-B-O-N [25].…”

“…30 e/ o. Recent studies by us have shown that La-Si-O-N [18,19] and Ca-Si-O-N [34] glasses can be formed over wide compositional ranges by employing the electropositive elements in their metallic state or as metal hydrides as starting materials. The glasses retain high amounts of the electropositive elements and nitrogen and exhibit very high values of glass transition temperatures, microhardness and refractive index.…”