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- Grund Bäck, Lina, 1974-, et al.
(författare)
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Mixed alkali/alkaline earth‐silicate glasses : Physical properties and structure by vibrational spectroscopy
- 2019
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Ingår i: International Journal of Applied Glass Science. - : American Ceramic Society. - 2041-1286 .- 2041-1294. ; 10:3, s. 349-362
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Tidskriftsartikel (refereegranskat)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)Na2O–xK2O–10CaO–70SiO2 (x = 0, 5, 10, 15, 20)] or on the mixed alkaline earth effect [20Na2O–(10−y)CaO–yBaO–70SiO2 (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 Q3 group compared to the Q2 and Q4 groups as the high field strength ions Na+ or Ca2+ are substituted by their low field strength analogs K+ or Ba2+. 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.
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| 2. |
- Wójcik, Natalia A., et al.
(författare)
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The effect of nitrogen on the structure and thermal properties of beryllium-containing Na-(Li)-Si-O-N glasses
- 2019
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 522, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Two oxynitride glass series with the composition of 35Na2O-5BeO-(60-x)SiO2-xSi3N4 and 9Li2O- 27Na2O-5BeO-(59-x)SiO2-xSi3N4, were prepared. The glasses' topography and structure were studied by Scanning Electron Microscopy and Raman spectroscopy. The composition was analyzed by Inductively Coupled Plasma Optical Emission Spectrometer, SEM-EDS and nitrogen and oxygen elemental analyzer. Na-(Li)-Be-silicate glasses were found to contain up to approximately 3.4 (or 5.2 for EDS measurements) at.% of N, respectively. The samples were homogenous in their topography and compositions of their cross-sections.The presence of three-fold coordinated nitrogen atoms in Na-Be-Si-O-N glasses results in higher degree of polymerization as was observed by Raman spectroscopy. The spectrum of analogous glasses with lithium did not show a significant decrease in Q2 units but exhibit the presence of Q4 units which also indicates a polymerization of the network. The incorporation of nitrogen in these glasses leads to the increase of the glass transition temperature and thermal stability.
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