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

Preparation of oxynitride glasses from woody biofuel ashes

“…A comparison of the compositions of the glasses and the starting mixtures suggests that the synthesis process involves dissociation and evaporation of some of the components, resulting in a shift from the theoretical chemical composition. Elemental losses have previously been reported for different kinds of oxynitride glasses [9,21,[32][33][34][35][36][37]. The elemental analyses show that the prepared glasses have lower contents of nitrogen and Ca metal than the starting mixtures, and that a loss of these elements thus had occurred at the relatively high melting temperatures used.…”

“…It is also known that the incorporation of nitrogen increases the glass density due to a significant fraction of three coordination N in the glass, but previous investigation in mixed alkali-earth oxynitride glasses shows that the density also depends strongly on the atomic weight of the elements and increases with increasing atomic weight of the element [9]. For silicate glasses, a high T g is associated with a high strength of chemical bonding and a high degree of polymerization of the network.…”

“…Since, the late 70's, oxynitride glasses have been the subject of many studies, from both scientific and technological points of view, as it was realized that incorporation of nitrogen into silicate glasses causes profound alteration of their mechanical properties such as strength, toughness, elastic modulus, and hardness [9][10][11][12][13][14][15][16][17][18][19]. Oxynitride glasses also show, in comparison with corresponding pure oxide glasses, higher glass transition temperatures and lower thermal expansion coefficients [17,[20][21][22].…”

Viscosity of high-nitrogen content Ca–Si–O–N glasses

“…However, an alternative synthesis method developed by us has enabled the preparation of oxynitride glasses with significantly higher concentrations of nitrogen, as well as modifier additives, in various systems. [8][9][10][11] In the synthesis route, the modifier is introduced as a metal or metal hydride, which reacts with nitrogen gas at relatively low temperatures and forms reactive nitrides with no surface oxide layer. Theses glasses retain high amounts of the electropositive elements and nitrogen and exhibit very high values of glass transition temperatures, microhardness, elastic moduli and refractive index.…”

“…Measured physical properties for the three Ca-Si-O-N glasses are given in Table 1. 11,15 In this table, the number of bridging anions per tetrahedron (n BO* ) was roughly estimated assuming all silicon atoms are 4-fold coordinated to anionic species and all anions are bonded to cationic species. This number is defined as:…”