Mixed alkali/alkaline earth‐silicate glasses: Physical properties and structure by vibrational spectroscopy

Abstract

In this article, we investigate the correlation of selected physical properties with structural changes in quaternary mixed modifier alkali/alkaline earth oxide silicate glass systems, focusing either on the mixed alkali effect [(20−x)Na 2 O-xK 2 O-10CaO-70SiO 2 (x = 0, 5, 10, 15, 20)] or on the mixed alkaline earth effect [20Na 2 O-(10−y)CaO-yBaO-70SiO 2 (y = 0, 5, 10)]. A maximum microhardness and packing density, as well as a minimum glass transition temperature were observed for mixed alkali glasses. The mixed alkaline earth glasses do not exhibit any clear extrema in any of the properties studied. The hardness and glass transition temperature decreases, while the density and molar volume increases with increasing BaO content.Raman spectroscopy showed an increase in the Q 3 group compared to the Q 2 and Q 4 groups as the high field strength ions Na + or Ca 2+ are substituted by their low field strength analogs K + or Ba 2+ . In the mixed alkali series, the high field strength ion Na + , seems to push the low field strength ion K + into lower energy sites when present simultaneously, while such an effect is not apparent for the mixed alkaline earth glasses, where the far IR spectra of mixed glasses are equivalent to the weighted averages of the pure glasses. K E Y W O R D Smixed modifier effect, silicate glass, glass transition temperature, hardness, Raman spectroscopy and IR spectroscopy 350 | GRUND BÄCK et al.

Electronic polarizability in silicate glasses by comparison of experimental and theoretical optical basicities

“…Grund Bäck et al 63 examined the structure of ternary Na 2 O/K 2 O–CaO/BaO–SiO 2 glasses from Raman scattering spectroscopy measurements and reported the relative Raman area for Q n species in SiO 4 tetrahedral units. For example, 20Na 2 O–10CaO–70SiO 2 glass has the fractions of Q 2 = 0.145, Q 3 = 0.602, and Q 4 = 0.253, indicating that the main Q n species in these glasses is SiO 4 units with three BOs and one NBO.…”

Synthesis, structural characterization, and thermal properties of Ca‐ and La‐doped soda‐lime glasses by laser melting

“…The most prominent band is centered near 1080‐1095 cm −1 and is assigned to the asymmetric stretching vibration of Si‐O bonds in Q 3 type silicate tetrahedra (for band assignments see Refs. [20‐22,25‐29] and references therein). The shoulder at about 1200 cm −1 , which is most pronounced in the IR spectra of the least modified glasses 1Ca and 1La and remains strong for all other La‐glasses analyzed, reflects the presence of a significant population of Q 4 type tetrahedra, that is, of fully bridged silicate tetrahedra.…”

“…In the far‐IR region, there is a broad envelope at about 265 cm −1 that shows a relative increase with Ca‐addition (Figure 2A). This envelop should originate from the overlap of bands due to Na + ‐site vibrations around 200‐250 cm −1 and 20‐22,27 Ca 2+ ‐site vibrations around 240‐280 cm −1 30‐32 depending on glass composition. The far‐IR profile remains almost constant for the La‐series, with no La 3+ ‐site vibration band being distinguished at ca.…”

Structural modifications of soda‐lime silicate glasses using femtosecond pulse‐laser irradiation

“…Red dash line indicates experimental data, black dash line is simulated coordination. Left, hollow points represent experimental values found in literature using similar Raman deconvolution and 29‐Si NMR; red, 20 blue, 15 green and magenta 47 . Right, hollow points represent simulated and experimental values; purple, 59 violet, 47 and orange 15 [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Similarly, Chan et al 7 and Krol 19 demonstrated densification through the formation of fewer‐membered ring structures after exposure to a tightly focused femtosecond laser pulses. Silicon coordination has been quantified using the high‐frequency region (800‐1200 cm −1 ) of Raman spectra fit primarily to Gaussian or Lorentzian bands, although the latter has not shown significant changes 20,21 …”