Elastic Properties and Hardness of Mixed Alkaline Earth Silicate Oxynitride Glasses

Abstract

The incorporation of nitrogen as a second anion species into oxide glasses offers unique opportunities for modifying glass properties via changes in glass polymerization and structure. In this work, the compositional dependence of elastic properties and the nanoindentation hardness of mixed alkaline-earth silicate oxynitride glasses containing a high amount of nitrogen (>15 at.%, c.a. 35 e/o) were investigated. Three series of silicon oxynitride glass compositions AE–Ca–Si–O–N glasses (where AE = Mg, Sr, and Ba) having varying amounts of modifiers were prepared using a new glass synthesis route, in which a precursor powder of metal hydrides was used. The obtained glasses contained high amounts of N (19 at.%, c.a. 43 e/o) and modifier cations (26 at.%, c.a. 39 e/o). Mg–Ca–Si–O–N glasses had high values of nanohardness (12–16 GPa), along with a reduced elastic modulus (130–153 GPa) and Young’s modulus (127–146 GPa), in comparison with the Sr–Ca- and Ba–Ca-bearing oxynitride glasses. Both the elastic modulus and the nanohardness of AE–Ca–Si–O–N glasses decreased with an increase in the atomic number of the AE element. These property changes followed a linear dependence on the effective cation field strength (ECFS) of the alkaline earth (AE) modifier, according to their valences and ionic radii. No mixed alkaline-earth effect was observed in the current investigation, indicating that the properties were more dictated by the nitrogen content.

BO3/BO4 Intermixing in Borosilicate Glass Networks Probed by Double-Quantum 11B NMR: What Factors Govern BO4–BO4 Formation?

“…Notwithstanding a non-negligible { P B pq } data scatter within each relatively small K –0.75 and 2.0–2.1 glass series, once considering both the M z + content ( x M ; eq ) and the CFS, a significant impact from the network modifier reservoir on the borate group intermixing becomes evident across the full BS glass ensemble. Focusing on the B [4] –O–B [4] linkages, the { P B 44 } set correlated well with the effective CFS defined by , (Tables and S5)­ yielding the following empirical best-fit expression which is displayed in Figure a. Notably, the exponent 0.425 ≈ 1/2 of eq (with uncertainty ±0.033) implies that the deviation from a perfect B [4] –O–B [4] avoidance ( P B 44 = 0) grows approximately as .…”

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

“…Out of the alkaline‐earth bearing M–(Al)–Si–O–N glass families, those with M 2+ = {Ca 2+ , Mg 2+ } have received most attention, 7,9,11,13,19,26–29 but a few studies also targeted Sr 2+ and Ba 2+ bearing glasses 7,19,30–34 . The formation of Ca–Al–Si–O–N glasses and related ones have primarily been examined for specimens prepared by melting oxides and nitrides of Si and/or Al in N 2 atmosphere; then, a traditional melt‐quench procedure may produce glasses with N contents reaching up to ≈7 at.%, which corresponds roughly to ≈16 equivalent percent (eq.%) of N out of all anions (O and N) 5,11,19,21 .…”

Impact of the Atomic Packing Density on the Properties of Nitrogen-Rich Calcium Silicate Oxynitride Glasses

“…25 e/o. Recently, few studies have reported that AE/RE–Si–O–N (where “AE” is alkaline-earth and “RE” is rare-earth) glasses can be formed by incorporating a metal modifier such as metal hydride or even pure metal in the reaction mixture rather than using metal oxides, as typically used with silicon nitride (Si 3 N 4 ) as the N source yielding oxynitride glasses, with N content of up to 60 e/o with exceptional thermal, mechanical, and optical properties [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”