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Redox reactions and structure - properties relations in mixed alkali/alkaline earth glasses: - The role of antimony oxides during the fining process- A structural study of copper(I) and copper(II)
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET). (Glass group)
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

It is important to optimize glass compositions for their specific purpose but also for the efficiency of the production process, the manufacturing of glass. This will be beneficial economically and environmentally. Today many processes and glass compositions are already optimized, but due to more strict legislation on toxic elements and substances there must be changes in many glass compositions. One of these elements is antimony; the oxide is used as fining agent to obtain a bubble free glass within a reasonable process time. One aim with this thesis is to obtain a deeper understanding of the fining mechanism in 20R2O-10MO-70SiO2 (R=Na and/or K, M = Ca and/or Ba, Mg, Sr) glasses in order to minimise the amount of Sb2O3. Another intention is to study the structure of 20R2O-10CaO-70SiO2 (R = Na, K) with Cu2+ as probe ion and thus get a deeper knowledge of the surrounding glass matrix.  The optical basicity scale is used to determine the acid/base character of the different glass compositions.

 

Fining efficiency results showed a remarkable increase of the number of remaining bubbles when the glass contains either approximately equal amounts of Na and K or Ca and Ba, Mg or Sr. The much higher number of bubbles in the potassium containing glasses compared to the sodium containing is explained by the increase in viscosity, the increase in optical basicity and thus lower oxygen activity. The differences in the fining efficiency when altering alkaline earth ions cannot be explained by the optical basicity values, it seems to be a more complicated situation.

 

This thesis also reports maximum in Vickers hardness and packing density as well as minimum in glass transition temperature for the mixed alkali glasses. The mixed alkaline earth glasses do not exhibit any clear nonlinear behaviour. Raman spectroscopy measurements showed a variation in the network connectivity which has a clear relation to the optical basicity of the different glass compositions. The combination of UV-Vis-NIR and X-ray absorption spectroscopy measurements showed that the coordination sphere for Cu(II) is a tetragonal distorted octahedron with two elongated Cu-O bonds along the z axis. There were no trends in the degree of tetragonal distortion, thus it was about the same for all the investigated glass compositions. Cu(I) is found to be coordinated by two oxygen ligands in mainly linear coordination sphere, evidenced from X-ray absorption spectroscopy.

Ort, förlag, år, upplaga, sidor
Växjö: Linnaeus University Press, 2015. , s. 73
Serie
Linnaeus University Dissertations ; 231
Nyckelord [en]
Fining, oxygen activity, redox reactions, mixed alkali effect, mixed alkali silicate glasses, copper, antimony
Nationell ämneskategori
Samhällsbyggnadsteknik
Forskningsämne
Teknik, Glasteknologi
Identifikatorer
URN: urn:nbn:se:lnu:diva-46782ISBN: 978-91-87925-82-5 (tryckt)OAI: oai:DiVA.org:lnu-46782DiVA, id: diva2:861631
Disputation
2015-11-06, Södrasalen, Universitetsplatsen 1, Växjö, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2015-10-20 Skapad: 2015-10-19 Senast uppdaterad: 2018-12-12Bibliografiskt granskad
Delarbeten
1. Compositional effect on fining and oxygen activity in mixed alkali silicate glasses
Öppna denna publikation i ny flik eller fönster >>Compositional effect on fining and oxygen activity in mixed alkali silicate glasses
2009 (Engelska)Ingår i: European Journal of Glass Science and Technology. Part A: Glass Technology, ISSN 1753-3546, Vol. 50, nr 1, s. 62-64Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This study monitors, in situ, how alterations of the glass composition affect the results of fining and the oxygen activity (aO2) of the melt. The number of bubbles in annealed glass samples was determined in order to evaluate the fining efficiency. Electrochemical measurement of aO2 was used to monitor in situ the fining charcteristics and conditions of Na2O-K2O-CaO-SiO2 glasses. The glasses investigated had a constant alkali oxide content, but a varying ratio of Na2O/(Na2O+K2O). The Sb2O3 content was o.2 mole-% and NaNO3 or KNO3 was added as oxidising agent in most of the glasses. The results show that the number of bubbles decreases from approximately 1100 to 200 bubbles/ 100 g glass and that aO2 at 1400 deg C increases from 0.2 to 1.2 bar in the glass melt when increasing the Na2O/(Na2O+K2O) ratio from 0 to 1.

Ort, förlag, år, upplaga, sidor
Society of Glass Technology, 2009
Nyckelord
glass. oxygen activity, fining
Nationell ämneskategori
Teknik och teknologier
Forskningsämne
Teknik
Identifikatorer
urn:nbn:se:vxu:diva-4240 (URN)
Tillgänglig från: 2009-03-09 Skapad: 2009-03-09 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
2. The influence of basicity on oxygen activity and antimony oxide fining efficiency in alkali alkaline earth aluminosilicate glasses
Öppna denna publikation i ny flik eller fönster >>The influence of basicity on oxygen activity and antimony oxide fining efficiency in alkali alkaline earth aluminosilicate glasses
2009 (Engelska)Ingår i: European Journal of Glass Science and Technology. Part A: Glass Technology, ISSN 1753-3546, Vol. 50, nr 5, s. 241-246Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The number of bubbles was monitored in antimony oxide fined R2O-MxOy-SiO2 and R2O-CaO-Al2O3-SiO2 glasses (R = Na, K; M = Ca, Mg, Ba, Sr, Zn, B, Al, Ti, x = 1 or 2, y = 1, 2 or 3) in order to evaluate the fining efficiency. Electrochemical measurements of oxygen activity were used to, in situ, monitor the fining characteristics and conditions in some of the investigated glass melts. The results showed that an increase of the calculated optical basicity was related to an increased number of bubbles in the glass samples. The oxygen activity in the melt during fining decreased with increased optical basicity.

Ort, förlag, år, upplaga, sidor
Sheffield: Society of Glass Technology, 2009
Nationell ämneskategori
Materialteknik
Forskningsämne
Teknik, Glasteknologi
Identifikatorer
urn:nbn:se:vxu:diva-6605 (URN)
Tillgänglig från: 2010-01-13 Skapad: 2010-01-13 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
3. Electronic spectra and molar extinction coefficient of Cu2+ in mixed alkali-alkaline earth-silica glasses
Öppna denna publikation i ny flik eller fönster >>Electronic spectra and molar extinction coefficient of Cu2+ in mixed alkali-alkaline earth-silica glasses
2015 (Engelska)Ingår i: Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B, ISSN 1753-3562, Vol. 56, nr 1, s. 8-14Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

CuO is a very common colorant in blue to turquoise-blue glasses. It is well known that the absorption peak at about 800 nm for silicate glasses is caused by Cu2+, octahedrally coordinated by 6 oxygen ions. It is also known that the [Cu+]/[Cu2+] ratio, the location of the absorption peak and the extinction coefficient of Cu2+ depends on the glass composition. Many investigations have been published with CuO as a colouring agent, but almost none with a mix of Na2O and K2O or CaO and BaO in the base glass. In this study, a base glass composition of 20R2O-10MO-70SiO2 (mol%, R=Na, K and M=Ca, Ba) is used and 0.40 mol% CuO is added. The molar extinction coefficient of Cu2+ is determined for the glasses and peak positions and heights are also presented and discussed.

Nationell ämneskategori
Materialkemi
Forskningsämne
Teknik, Glasteknologi
Identifikatorer
urn:nbn:se:lnu:diva-45917 (URN)000352247300002 ()2-s2.0-84944036401 (Scopus ID)
Tillgänglig från: 2015-08-27 Skapad: 2015-08-27 Senast uppdaterad: 2017-06-01Bibliografiskt granskad
4. Physical properties and Raman Spectroscopy of mixed alkali/alkaline earth silicate glasses
Öppna denna publikation i ny flik eller fönster >>Physical properties and Raman Spectroscopy of mixed alkali/alkaline earth silicate glasses
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Annan materialteknik
Forskningsämne
Teknik, Glasteknologi
Identifikatorer
urn:nbn:se:lnu:diva-46869 (URN)
Tillgänglig från: 2015-10-26 Skapad: 2015-10-26 Senast uppdaterad: 2019-01-18Bibliografiskt granskad
5. X-ray and UV-Vis-NIR absorption spectroscopy studies of the Cu(I) and Cu(II) coordination environments in mixed alkali-lime-silicate glasses
Öppna denna publikation i ny flik eller fönster >>X-ray and UV-Vis-NIR absorption spectroscopy studies of the Cu(I) and Cu(II) coordination environments in mixed alkali-lime-silicate glasses
Visa övriga...
2019 (Engelska)Ingår i: Journal of Non-Crystalline Solids: X, ISSN 2590-1591, artikel-id 100029Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The local structures of Cu(I) and Cu(II) in (20-x)Na2O-xK2O-10CaO-70SiO2 glasses with a copper content of 0.4 mol% have been investigated by Cu K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). Complementary data for Cu(II) was derived using UV–Vis-NIR spectroscopy. Indication for mainly linear two-fold coordination of the Cu+ ion was found by both EXAFS and XANES, but other coordination between Cu+ and O2– cannot be excluded. The Cu(I)O bond lengths were found to be 1.79–1.83 ± 0.02 Å. EXAFS results showed that Cu(II) was mostly present in a Jahn-Teller distorted environment with oxygen, an octahedron with four shorter Cu(II)O bonds and two longer in axial position. The equatorial bond lengths were found to be 1.89–1.91 ± 0.02 Å and the axial 2.20–2.24 ± 0.02 Å with no effect of the Jahn-Teller distortion of the octahedron when the glass composition was altered.

Ort, förlag, år, upplaga, sidor
Elsevier, 2019
Nationell ämneskategori
Keramteknik Materialkemi
Forskningsämne
Teknik, Glasteknologi
Identifikatorer
urn:nbn:se:lnu:diva-46870 (URN)10.1016/j.nocx.2019.100029 (DOI)2-s2.0-85068376725 (Scopus ID)
Tillgänglig från: 2015-10-26 Skapad: 2015-10-26 Senast uppdaterad: 2019-09-02Bibliografiskt granskad

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