Indentation moduli and microhardness of RE–Si–Mg–O–N glasses (RE=Sc, Y, La, Sm, Yb and Lu) with different nitrogen content

Structure and rheological properties of the RE–Si–Mg–O–N (RE=Sc, Y, La, Nd, Sm, Gd, Yb and Lu) glasses

“…The different valence of Eu (2+ instead of 3+) and an increase in coordination number in the case of lanthanides with high atomic numbers were considered as responsible for some anomalous changes in the properties [16]. Our previous studies on RE-Si-Mg-O-N glasses confirmed the deviations from linear dependence of microhardness and indentation moduli at room temperature in the case of Sc-and Y-containing oxynitride glasses [23,24]. However, glass transition temperatures (T g ) of Y-containing glasses fit the dependence while the T g of Yb-containing glasses does not [25].…”

“…Based on the previous conclusions (see Figs. 1(A), 2(A), 4 and 5) the deviations of various properties of Y and Sc-containing glasses seen in ionic radius dependencies [15,16,23,24,26] are the artifacts of the representation [26].…”

“…As a result, a glass network containing small lanthanides, such as Lu, has a tighter structure and better properties than the glasses containing lanthanides with greater ionic radii. For instance, the replacement of La by Lu in oxide glasses caused 0022 [21][22][23][24][25].5% and 16-22% increases in YoungÕs modulus in oxide and oxynitride glasses, respectively; hardness increased by 13-16% [17]. Glass transition temperatures in La-glasses without and with 20 eq.% of N were approximately 882 and 960°C, whereas they were $916 and $1010°C in Lu-containing glasses [17].…”

“…However, the number of detailed structural studies on the oxynitride glasses is limited and they cover only some rare-earth elements [10][11][12]. These studies provide a basic understanding of the compositional effect but they cannot explain the deviations from linearity in properties, which were observed for some lanthanides and for non-lanthanide additives [15,16,[23][24][25][26]. The different valence of Eu (2+ instead of 3+) and an increase in coordination number in the case of lanthanides with high atomic numbers were considered as responsible for some anomalous changes in the properties [16].…”

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

“…The microhardness also varies substantially with the type of modifier; e.g. Lu-and Yb-containing glasses exhibit higher hardness values than corresponding La-containing glasses [30].…”