The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 °C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (α). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.

For the solar energy industry to increase its competitiveness, there is a global drive to lower the cost of solar-generated electricity. Photovoltaic (PV) module assembly is material-demanding, and the cover glass constitutes a significant proportion of the cost. Currently, 3-mm-thick glass is the predominant cover material for PV modules, accounting for 10%–25% of the total cost. Here, we review the state-of-the-art of cover glasses for PV modules and present our recent results for improvement of the glass. These improvements were demonstrated in terms of mechanical, chemical and optical properties by optimizing the glass composition, including addition of novel dopants, to produce cover glasses that can provide (i) enhanced UV protection of polymeric PV module components, potentially increasing module service lifetimes; (ii) re-emission of a proportion of the absorbed UV photon energy as visible photons capable of being absorbed by the solar cells, thereby increasing PV module efficiencies and (iii) successful laboratory-scale demonstration of proof of concept, with increases of 1%–6% in Isc and 1%–8% in Ipm. Improvements in both chemical and crack resistance of the cover glass were also achieved through modest chemical reformulation, highlighting what may be achievable within existing manufacturing technology constraints. © 2020 The Authors.

Diffusion kinetics and structural properties of chemically strengthened titania-doped soda-lime silicate glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry. The glasses were ion exchanged, whereby Na+ in the glass was replaced by K+ in a molten salt bath, at four different treatment temperatures between 350 and 500 °C. The alkali diffusion coefficient, DK-Na, and corresponding activation energy were calculated to be between 3.26×10−12 and 4.47×10−11 cm2s−1 and between 101.1 kJmol−1 and 105.6 kJmol−1, respectively. DK-Na was observed to decrease as the TiO2 concentration was increased. Raman analysis showed Q3-silicate species with different bond lengths, which was attributed to surface compressive stresses, and increasing Si-O-Si bond angle with increasing ion exchange temperature. Ti3+ ions exist as a minor species in the glasses and its concentration depends on the TiO2 content. Deconvolution of the optical absorption spectra reveals Jahn-Teller compressive distortion of the Ti3+ octahedral coordination.

Diffusion kinetics and structural properties of chemically strengthened titania-doped soda-lime silicate glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry.

Chemical strengthening (CS) is frequently used to strengthen thin glasses. CS of glass is based on ion exchange of larger ions from a molten salt into glass. Both the ion and counter ion are conventionally monovalent alkali ions.

Diffusion kinetics and structural properties of chemically strengthened titania-doped (TiO2) soda-lime silicate (SLS) glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry. The glasses were ion exchanged, whereby Na+ in the glass was replaced by K+ in a molten salt bath, at four different treatment temperatures between 350 and 500 °C.

The following samples were prepared and analyzed by X-ray Photoelectron Spectroscopy (XPS): (1) SLS, (2) 4.7% TiO2, and (3) 9.9% TiO2. The ion exchange procedure was performed for 5 h at four different temperatures below Tg (350, 400, 450 and 500 °C). Before XPS measurements, the samples were wet-etched using hydrofluoric (HF) acid to produce samples with six different etching depths.

The Raman scattered light was detected in the backscattering configuration employing linear polarization and 2400 lines/mm grating, and a 100x objective lens. Depth profile spectra were collected at six different depths of 0, 10, 20, 30, 40, and 50 µm for each glass sample, employing 12 scans with a 10 s exposure time for each scan.

Spectrophotometric measurements were conducted before and after K+/Na+ ion-exchange treatmeatment for 5 h at 500 °C, collected between 300 and 2500 nm.

In the building sector, net-zero energy performance targets and reduction of CO2 emissions are the main drivers for building integrated photovoltaics. Recent market studies [10,18,19] show the history and perspective of the global market in the BIPV sector and calculate a global compound annual growth rate of ~ 40 % from 2009 up to 2020.

In Europe, the BIPV market is in a transition. The past decades of a slowly emerging BIPV market have been characterized by the original dominant value of BIPV: a building that communicates an image of sustainability and innovation. Payback time or "return on investment" have not been the major parameters in the decision process for applying BIPV. This is changing now. In most European countries, the new regulations on energy performance in buildings (derived from the European Energy Performance of Buildings Directive and the Directive on energy efficiency) have been translated in national regulations/laws, stating that all new (and freshly refurbished) buildings of the EU member states should be nearly zero energy buildings (nZEBs) by 2020. Thus, the time for the regulations to become mandatory is very near. It is expected that the energy performance regulations are now taking over as the main driving factor for the BIPV market and that should have huge consequences in removing the difference between a conventional building component and a BIPV component both in aesthetical and construction terms. This has led to intensified research and development aiming to create BIPV products that come in a variety of colours and sizes, while at the same time being as close as possible to existing building components, to its requirements and how it is considered by the construction industry.

The given market overview of state-of-the-art coloured BIPV products clearly reveals that for all parts of a BIPV module (glass, polymers, PV-active layers), there are technical solutions available for colouring. Pilot projects utilizing coloured BIPV products have been built in numerous (mainly European) cities clearly demonstrating the maturity of these solutions.

The key aspect that has been slowing down the progress of implementation of these aesthetically appealing and technically sophisticated new products into a wider market are the costs. In this respect, a lot of effort has been made to improve and optimize the relationship between colour and efficiency/power generation of BIPV elements. The results of the past and on-going innovative research and intensified fundamental considerations are also summarized in this report.

Besides the colour perception of the coloured BIPV elements under solar irradiation which is essential for the acceptance of the exterior appearance of a building, also transparency and inside visual comfort of BIPV – windows and façade elements are essential for the users and inhabitants.

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  de-creases, 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.

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 O^2– 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.

Solar energy is promising renewable energy where glass is an important material and have a significant impact on the efficiency of the photovoltaic (PV) module. The cover glass of PV-modules constitutes a large part of the total weight of the unit. In a recent Solar-ERA.NET project, LIMES (www.limes.nu), have we been aiming towards developing 1 mm thin glass for PV modules by improving the indentation mechanical properties and by investigating a novel thermo-chemical strengthening method.

Starting from traditional soda-lime-silicate float composition different components was studied in a DoE fashion. The mechanical properties were studied using nano- and microindentation, the chemical durability by P98 analysis and weathering experiments. The findings resulted in a suggested composition for improving the properties of float glass by adding small amounts of zinc and titanium oxide as well as increasing the amount of aluminum and magnesium oxide. The components found to improve the chemical resistance were alumina, zirconia, zinc, lanthanum and titanium oxide. The surface hardness, crack- and scratch resistance were improved when magnesia was replaced with zinc oxide. When magnesia was replaced with titania, the hardness was increased.

Some results from the thermo-chemical strengthening experiments will be presented. Heating and quenching in a reactive gas atmosphere using aluminum precursors have resulted in chemically modified surface in addition to the thermal strengthening.

The aim of the project presented in the report was that construction and demolition waste will be recycled or recycled to a greater extent and at the same time fulfil the quality requirements on the materials.

The purpose of the project has been to map and compile the knowledge and experience of the technical aspects of circular flows of building materials, focusing on quality issues, identifying new projects that can reduce the amount of construction and demolition waste deposited or burned, as well as creating new networks. There is widespread knowledge in the construction industry about these issues and there are also a wide range of research results in different areas. In the project, knowledge and experience have been gathered through literature studies, workshops and seminars, study visits and interviews.

The first part of the report discusses general technical experiences and challenges in different parts of the building chain, while challenges for specific material groups are discussed in the second part of the report. These material groups are polymeric materials, flat glass, stone wool, glass wool, plasterboard, crushed concrete, wood and wood-based materials. The report also presents a survey conducted by Optimera among their professional costumers, which aimed at collecting their experiences and views on sustainable construction.

In general, we can find that there are major challenges in increasing recycling rates for demolition and refurbishment waste. For installation and construction waste, the technical challenges are not as big. Challenges and conditions for increased recycling and reuse with retained good quality vary between different types of materials / products, type of construction project and intended use.

The report proposes a number of proposals in areas where work can be continued. These include improved / expanded inventory for demolition and refurbishment, routines and sampling methods, proper sorting, handling and storage to ensure the right quality, to provide the ability to separate compound materials, logistics, production technology and quality assurance. The results also show the importance of education, networks and meeting places and that research projects are conducted interdisciplinary. There are good opportunities for increased recycling through cooperation throughout the entire building chain.

Failure of photovoltaic modules frequently occurs as a result of degradation of their encapsulation material by destructive UV radiation. Transparent TiO2 and ZnO thin films could protect against these harmful wavelengths.

Failure of PV modules frequently occurs as a result of degradation of their encapsulation material by destructive UV radiation. Both the life expectancy and efficiency of PV modules can be improved by reducing the transmittance of the destructive UV radiation through the cover glass without compromising the transmittance in the visible wavelength region. In addition, if the absorbed UV photons can be down-shifted to wavelengths that can be more efficiently converted to electrical energy, an additional increase of the PV efficiency could be achieved. In this study we have investigated transparent ZnO and TiO₂ thin films deposited by spray pyrolysis on soda lime silicate float glass as functional layers on PV cover glass. The optical bandgap, UV-cutoff, UV-Vis transmittance, reflectivity (total and diffuse) and photoluminescence have been determined. The ZnO coating shifted the optical bandgap to longer wavelengths, resulting in a reduction of the transmittance of destructive UV radiation by up to ~85%. Distinct photoluminescence peaks at 377 nm and at 640 nm were observed for one of the ZnO samples. The TiO₂ coated glasses also showed an increased UV cutoff, which resulted in a reduction of transmittance of destructive UV radiation by up to 75%. However, no photoluminescence peaks could be observed from the TiO₂ films with 325 nm excitation laser, which can be explained by the fact that only indirect interband transitions are accessible at this excitation wavelength. Deposition of both ZnO and TiO₂ coatings resulted in a reduction of the transmitted light convertible by PV modules, by up to 12.3 and 21.8%, respectively. The implication of the results is discussed in terms of lifetime expectancy and efficiency of PV modules.

Antireflective coatings on glass have increasing applications, on e.g. cover glass of PV modules, display glass, spectacle lenses or window glazing’s. Sol-gel derived mesoporous coatings can be tuned both in terms of porosity and thickness, thus allowing tuning of the refractive index. Additionally, the sol-gel approach is bottom-up, which facilitates easy upscaling. In the current work we present dip-coated mesoporous silica coatings of different pore orientation and film thickness prepared on microscope glass slides and silicon wafers. The silica coatings were derived from TEOS (tetraorthosilicates) mixed with ethanol and diluted HCl. Hexagonal and cubic pore ordering of the thin films with a pore size in the range of 5-10 nm were obtained. The thin films were characterized in terms of non-contact profilometry, stylus profilometry,  nanohardness, scratch resistance, UV-Vis-NIR transmittance and UV-Vis-NIR reflectance. The thicknesses of the studied films varied from 100 nm up to several hundreds of nm without jeopardizing the film homogeneity. All the mesoporous films exhibited higher transmittance than the uncoated glass substrate. The film with hexagonal pore orientation has a somewhat higher nanohardness than the cubic one, however,  no difference was found in the scratch resistance for the films with different pore orientations.

TiO2 is an important oxide for property modifications in the conventional soda lime silicate glass family. It offers interesting optical and mechanical properties, for instance, by substituting heavy metals such as lead in consumer glasses. The compositional effects on the hardness, reduced elastic modulus and crack resistance as determined by indentation of chemically strengthened (CS) TiO2-doped soda lime silicate glass was studied in the current paper. The CS, which was performed by a K+ for Na+ ion exchange in a molten KNO3 salt bath at 450 °C for 15 h, yielded significant changes in the indentation mechanical properties. The hardness of the glass samples increased, and this was notably dependent on the SiO2, CaO and TiO2 content. The reduced elastic modulus was less affected by the CS but showed decrease for most samples. The crack resistance, an important property in many applications where glasses are subjected to contact damage, showed very different behaviors among the series. Only one of the series did significantly improve the crack resistance where low CaO content, high TiO2 content, high molar volume and increased elastic deformation favored an increased crack resistance.

Titanium oxide has been added to the conventional soda lime silicate composition that is the most used glass in different applications. Surface mechanical properties through indentation using both nano- and micro-indenter has been studied both before and after chemical strengthening of the different glass samples.

Adding alumina to the conventional soda lime silicate glass composition improves many properties, however, also increases the viscosity. Alumina doping of soda lime silicate glasses is investigated and its implications to high temperature viscosity as SiO₂ is replaced by Al₂O₃.

Soda lime silicate is an important industrial glass type, it is used in, e.g., windows, containers, household glasses, displays, cover glasses and in automotive glazing. The importance of soda lime silicate glass originates from the forming ability that enables low-cost manufacturing but also relatively high hardness, good chemical durability, and the essential transparency in the visible range. However, soda lime silicate glass suffers from brittleness and has a relatively low resistance towards surface defects. Therefore, is the practical strength of commercially available glass in the soda lime silicate glass family limited. The mechanical properties of glass is of great importance in various applications. Chemical strengthening (CS) of glass has become a successful process that today is used in many applications. It makes glass stronger by exchanging larger ions from a molten salt bath with smaller ions from the glass and thereby inducing compressive stresses in the surface. However, soda lime silicate glass is typically not well-suited for this process and therefore has the effect of dopants on surface mechanical properties as result of CS been studied. Hardness, reduced elastic modulus and crack resistance were studied. The CS was performed in a molten KNO3 salt bath at 450 °C. The results will be discussed in relation to the compositional and structural changes.

Glass materials are essential in everyone’s life by enabling daylight to reach the interior of our buildings,being the primary component for communication via optical fibers and a key component in electronic devices as protective cover and/or dielectric material. It is also an essential component in solar energy applications which comprise, e.g., photovoltaics , solar thermal collectors, greenhouses and algae reactors, by acting as a protective and light transmitting barrier. Adding functionalities to glass in an intelligent way creates opportunities to enhance the properties of the glass material for its use. There are several possibilities to add functionalities and the wider concept Transparent Intelligence will be briefly introduced and how it can aid our efforts to overcome today’s societal challenges. Glass as a cover material for solar energy applications constitutes a significant part of the costs and isan important component for efficient light capture and protection to the environment. The research and development of cover glass for solar energy applications have so far received limited attention eventhough it is an important material for our future sustainable development. Recent research efforts have provided knowledge of which properties that needs to be optimized ‐ balancing efficiency, service lifetime and cost. The challenges of cover glass for different solar energy applications differs somewhat but all have in common the efficient solar light capture and protection to the environment. Thus, theknow‐how can be used in several different industrial sectors. The fundamentals of cover glasses for solarenergy applications as well as previous and on‐going project concepts will be presented. This includes i) state‐of‐the‐art of cover materials for greenhouses, ii) results on optimization of cover glass for photovoltaics, iii) initial results on how to provide both anti‐reflective and anti‐soiling properties,iv) results on broadband antireflective coatings for solar thermal energy, and v) other promising concepts. At last will some future challenges and needs be discussed, e.g., in relation to the concept ofideal material choices for PV.

Glass materials are an essential component in solar energy applications which comprise, e.g., photovoltaics, solar thermal collectors, greenhouses, and algae reactors, by acting as a protective and light transmitting barrier [1, 2]. Adding functionalities and optimizing the glass and coatings in an intelligent way creates opportunities to enhance the properties of the cover glass material for its use. 

Glass as a cover material for solar energy applications constitutes a significant part of the costs and a major part of the weight. However, glass is an important component for efficient light capture and protection to the environment. The R&D of cover glass for solar energy applications have so far received limited attention even though it is an important material for our future sustainable development and will likely require an increase of the flat glass production in the future. Recent research efforts have provided knowledge of which properties that needs to be optimized - balancing efficiency, service lifetime and cost. The challenges of cover glass for different solar energy applications differs somewhat but all have in common the efficient solar light capture and protection to the environment. Thus, the know-how can be used in several different industrial sectors. The fundamentals of cover glasses for solar energy applications as well as previous and on-going project concepts will be presented. This includes i) state-of-the-art of cover materials for greenhouses [2], ii) results on optimization of cover glass for photovoltaics [3, 4], iii) initial results on how to provide both anti-reflective and anti-soiling properties, iv) results on broadband antireflective coatings for solar thermal energy [5], and v) other promising concepts. At last, will some perspective of matters for further research be presented.

[1] J. Deubener, et al., Glasses for solar energy conversion systems. Journal of the European Ceramic Society, 2009. 29(7): p. 1203-1210. DOI: http://dx.doi.org/10.1016/j.jeurceramsoc.2008.08.009.

[2] M. Teitel, et al., Greenhouse and screenhouse cover materials: literature review and industry perspective. Acta Horticulturae, 2018. 1227: p. 31-44. DOI: https://doi.org/10.17660/ActaHortic.2018.1227.4.

[3] B.L. Allsopp, et al., Towards improved cover glasses for photovoltaic devices. Progress in Photovoltaics: Research and Applications, 2020. 28(11): p. 1187-1206. DOI: https://doi.org/10.1002/pip.3334.

[4] P. Sundberg, et al., Simultaneous chemical vapor deposition and thermal strengthening of glass. Thin Solid Films, 2019. 669: p. 487-493. DOI: https://doi.org/10.1016/j.tsf.2018.11.028.

[5] E. Zäll, et al., Aerosol-based deposition of broadband antireflective silica coating with closed mesoporous structure. Solar Energy Materials and Solar Cells, 2023. 250: p. 112078. DOI: https://doi.org/10.1016/j.solmat.2022.112078.

Solceller har länge varit ett lovande alternativ förelproduktion men har hittills begränsats av kostnad och effektivitet. Förstörre installationer har man för några år sedan kunnat nå samma pris som fördet rörliga elpriset och sedan 2002 har solcellsinstallationerna fördubblats för varje år som gått.

Thermal strengthening of glass is common for many different purposes including architecture, automotive, glasses for solar energy, tableware and occasionally also containers. It is an easy and relatively cheap method to make glasses stronger, however, with an Achilles heel that it can spontaneously fracture without the slightest applied external force. Though, fracture due to applied external force is the most common case, spontaneous fracture is rare. The current paper reviews the literature of spontaneous fracture and NiS inclusions and what kind of mitigation measures that have been done in order to reduce the frequency of spontaneous fracture. Finally is also an outlook for the alternative mitigation measures and their advantages as well as disadvantages. A personal perspective is given in discussions and gives an outlook to the most promising alternative methods to reduce and hopefully eliminate the NiS inclusions. These include multi-functional methods where not only the NiS inclusion issue is solved. 

Alla somhar läst Homeros epos Iliaden känner till Akilles, den grekiska mytologinsstörste hjälte som dessvärre hade en sårbar punkt, akilleshälen. Termiskthärdat glas är nästintill en perfekt produkt där man får både ett starkare glasoch ett betydligt säkrare glas genom den karaktäristiska sprickbildningen somger kantiga glasbitar som inte är så vassa och som ofta kallas granuler

Glass as a cover material for solar energy harvesting constitutes a significant part of the cost. Furthermore, is glass an important component for efficient light capture and protection to the environment. Research and development of cover glass is needed to increase the service lifetime and to reduce the cost per watt peak. Recent research efforts have provided knowledge of which properties that needs to be optimized balancing efficiency, service lifetime and cost. Challenges with the development of cover glass for efficient harvesting of solar energy will be discussed. Some recent results related to optimization of the glass composition for enhancing properties for the purpose and the deposition of functional thin films will be presented. The failure modes for PV modules and how glass can improve the resistance to failure will be discussed. Developments of transparent and robust multifunctional coatings that provide anti-reflective and anti-soiling properties on the outer glass surface are desired. On the interior surface are anti-reflective and chemical barrier multifunctional coatings desirable to increase transmission and reducing potential induced degradation (PID). Replacing the conventional silver strings in PV modules with transparent conductive materials and back-reflecting backsheet materials are among the promising techniques for further maximizing the efficiency.

The effect of TiO₂ on the high-temperature viscosity of soda-lime-silicate glass have been investigated. The silica-rich part of quaternary can be taken as a template for a wide variety of technical glasses. The measurements were performed using a rotational viscometer. The viscosities were recorded from 1550 °C downwards to 930 °C. The entire viscosity-temperature curves were fitted to the Angell-Rao viscosity equation and thermodynamic data were calculated using the method of Ojovan and the liquid fragility according to Angell. As TiO2 is replacing SiO2 it has a slight suppressing effect on the viscosity until the limit when Na2O/TiO2 ratio is less than 2, indicating a transformation of the structure of TiO₂, a remarkable increase in the fragility and viscosity is observed for the calculated low temperature region. The change is not as evident for the high-temperature region. CaO replaced by TiO2 gives almost no effect on the viscosity, however, as it approaches Na₂O/TiO₂≈2 it tends to crystallize at temperatures of 1000-1050 °C.

Theoretically is glass one of the strongest materials. However, due to surface defects inevitably formed during manufacturing, transport, handling and use of glass, the practical strength is greatly limited by stress-concentrations at crack tips under tension. Glass has limited fracture toughness which gives a practical strength that spans over several orders of magnitude. Despite this is glass used in a wide range of applications, where architectural and automotive are among the most apparent applications for the general public. The unreliable strength requires an unnecessary thick glass and this has a direct consequence on the sustainability fingerprint. The recent advances and an outlook on improving the practical strength of glass are presented including the improvement of surface quality, improving mechanical properties, and strengthening of glass together with a concept of non-destructive testing (NDT) of the glass strength. NDT of glass is a game-changer that, among other things, enables quality-sorting in the glass industry.

Glas är ett material med många tilltalande egenskaper vilket har medfört att det har ett stort antal användningsområden. Trots detta har materialet studerats förhållandevis lite och nu behövs en ny generation forskare som utmanar egenskaperna. Exempelvis den att glaset i vissa applikationer kan vara sprött och medföra att ”skadat” glas kan gå sönder vid liten belastning, något de flesta människor förmodligen upplevt någon gång. Ett faktum som till viss del begränsar tillämpningen och gör att glas har behövt vara ”onödigt” tjockt. Starkare och tåligare glas är och förblir därför ett viktigt forskningsområde.

Adding alumina to the conventional soda lime silicate glass composition improves many properties, however, also increases the melting temperature. In the current paper, alumina doping of soda lime silicate glasses and its implications to high temperature viscosity are investigated in order to verify the linearity when replacing SiO₂ for Al₂O₃. An anomaly in the linearly increasing viscosity was found when the ratio CaO/Al₂O₃ is <1, which is explained by Ca²⁺ acting as an inhibitor for viscous flow. The Angell and Rao and the Waterton-MYEGA models show very similar results, even for the extrapolated Tg. Thermodynamic data extracted using the Ojovan method generally increases linearly with the Al₂O₃ content. The Doremus fragility index shows a deviation in the linearity while the Angell fragility index on the other hand shows a linear increase with the Al₂O₃ content.

Glass is a common material in the everyday life. It is widely used in a variety ofapplications e.g. architectural, automotive, containers, drinking vessels, displays,insulation and optical fibers due to its universal forming ability, transparency, chemicaldurability, form stability, hardness and relatively low price. Flat glass is a wide market ofthe glass industry and generally ninety percent of all flat glass produced worldwide ismanufactured using the float forming process. There is a large market strive for thinnerand stronger glass in order to reduce costs, save energy, reduce environmental footprint,find new applications and to improve the working environment for labour working withmounting flat glass.

This study comprises the modification of flat/float glass surface by a novel route;exchange of ionic species originating from in-line vapour deposition of salt compared tothe conventional route of immersing the glass in molten salt baths. The aim of this workis to develop a novel process in order to improve the mechanical strength of flat/floatglass by introducing external material to the surface in a process with the obviouspotential to be automatic in industrial processes. Chemical strengthening has beenperformed by applying potassium chloride to the glass surface by vapour deposition andthermally activated ion exchange. The method presented here is anticipated to be used inproduction in the future and would make it possible to produce larger quantities ofchemically strengthened flat glass to a considerably lower cost.

Glass is a unique but unfortunately brittle material whose strength is primarily limited by the presenceof cracks on the surface [1]. The strength of glass is limited by the fact that very high stresses arise atthe crack tips when subjected to tensile load. In principle, without the presence of surface cracks, glasswould have a strength far exceeding many other structural materials, e.g., steel. The size and thedistribution of surface cracks vary greatly, which results in the strength of glass exhibit a great variationand thus requires that large safety margins must be applied for glass in practical applications, e.g., whenused as a load bearing building material.Today, there are no methods to determine the strength of flat glass non-destructively. Instead, thestrength is determined by different experimental methods requiring >10 samples for sufficient statistics.This procedure requires both lots of glassy materials and time. The future aim is to investigate if the useof nonlinear acoustic waves (NAW) could be an alternative for developing a standardized designstrength value. Developing a non-destructive inspection method for determining the glass strength is ascientific breakthrough that will have a great industrial impact for the sustainable development of glassmanufacturing.With the use of NAW it is possible to detect and quantify the defects in materials [2,3]. The nonlinearwaves are transmitted through the object and the nonlinear effects, caused by the defects in thematerial, corresponds to the level of damage in the material. This work present result from samplescontaining relatively precise defects. The defects were created using a microindenter with a sufficientload to cause indentation induced cracking in the glass. The indentations were created using a Vickersdiamond tip in the middle of commercial 4 mm float glass samples of the dimensions 10x10 cm2. Theapplied loads were 0.5N, 1N, 2N, 5N and 10N. The “damage value” of the sample series was thenquantified using the NAW technique. The fracture strength of the samples was correlated destructivelyusing a conventional ring-on-ring setup.The results show that there is a clear correlation between the indenter load, the damage value from theNAW inspection and the fracture strength. We noted that the standard deviation for the ring-on-ringtests for the 1N, 2N, 5N and 10N was low while the 0.5N and the reference samples presented a highstandard deviation. A possible explanation for this observation is that for 0.5N not all indents give radialcracks but in some cases the indentation produces only plastic deformation. The main conclusion fromthe research is that is possible to detect realistically large defects in glass using the non-destructive NAWmethod and these defects cannot be seen with the naked eye. Moreover, the results can be directlycorrelated with the strength of glass [4].

References[1] Veer, F.A. and Y.M. Rodichev, The structural strength of glass: hidden damage. Strength of Materials, 2011.43(3): p. 302-315. DOI: 10.1007/s11223-011-9298-5.[2] Persson, K., K. Haller, S. Karlsson, and M. Kozłowski, Non-destructive testing of the strength of glass by a nonlinearultrasonic method. Challenging Glass Conference Proceedings, 2020. 7. DOI: 10.7480/cgc.7.4498.[3] Haller, K., Doctoral Thesis: Acoustical measurements of material nonlinearity and nonequilibrium recovery.2008: Department of Mechanical Engineering, Blekinge Institute of Technology.[4] Karlsson, S., L. Grund Bäck, S. Andersson, K. Haller, M. Kozłowski, and K. Persson, Strength classification of flatglass for better quality – validation of method by well-defined surface defects and strength testing, in ÅForskReport,19-479. 2021: http://dx.doi.org/10.13140/RG.2.2.32992.40962.

Harvesting of solar energy through photovoltaic (PV) modules is an essential technology for increasing the share of renewable energy sources, both immediately and in the future. The glass cover material constitutes a significant part of the cost. Research and development of the cover glass is needed to increase the service lifetime and to reduce the cost per watt peak [1]. Recent research efforts in the LIMES project show that the addition of optically active components absorb harmful UV light and simultaneously convert those UV photons into visible light [2]. Thus, the profit is two-fold, increasing both service lifetime and efficiency by up to 4%. Further, the cover glass composition can be optimized to enhance the mechanical and chemical durability. It has been shown that it is possible to increase the indentation crack resistance [2] and the hydrolytic durability by three and four times respectively by modifying the glass composition. Thermal strengthening of glass for PV modules are required for mechanical durability. However, there is an increasing demand of light-weight PV modules, therefor is thermal strengthening of thin cover glass needed to meet the increasing demand. In-situ chemical vapour deposition (CVD) of Al₂O₃ and thermal strengthening of the cover glass provides an additionally crack resistant and chemically durable glass surface. Developments of transparent and robust multifunctional coatings that provide anti-reflective and self-cleaning properties on the outer glass surface are desired [4]. Thereby is maximal transmission and reduced soiling achieved. On the interior surface are anti-reflective and chemical barrier multifunctional coatings desirable to increase transmission and reducing potential induced degradation (PID) [5]. The LIMES concept has been demonstrated by quantitative measurements and as Si solar cells. The scale-up of the LIMES concept and additional material challenges to increase the efficiency and service lifetime will be discussed. Replacing the conventional silver strings in PV modules with transparent conductive tape and back-reflecting backsheet materials are among the promising techniques for further maximizing the efficiency.

Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Extraction of solar energy through solar cells is a promising technology for increasing the share of renewable energy sources, both now and in the future. Glass for solar cells is a significant part of the cost, and a necessity to develop to increase life expectancy and reduce the cost per watt recovered. In the LIMES project have adding optically active components been studied, these absorb harmful UV light and simultaneously converts those UV photons into visible light, which in turn can be converted into energy in solar cells. Thus, the profit is twofold, increasing both the lifetime and efficiency by up to 4%. Further, it has been studied how to optimize the mechanical and chemical properties of glass by optimizing the glass composition in order to increase the mechanical and chemical lifetime. It has shown that resistance to cracking of the new composition increases by a factor of 3 and that the chemical resistance is increased by a factor of 4. Novel thermo-chemical strengthening of glass has been demonstrated in the lab and giving rise to at least equal strengthening level and increases the crack resistance by a factor of 2. It enables the use of thinner glass and thus significantly lighter photovoltaic modules. In the thermo-chemical strengthening process, the glass surface composition is modified significantly by increasing the content of aluminum oxide and thus gives rise to improved properties. The thermo-chemical treatment increases the glass surface contact angle of water, which contributes to a self-cleaning glass. Multifunctional glass surfaces that are both anti-reflective and self-cleaning have been studied by two different approaches, nanostructured surface modification and porous antireflective coatings with photocatalytic degradation ability. Nanostructured glass surfaces gives rise to an increased light scattering and can thus effectively guide diffused light to the solar cells and simultaneously change the glass contact angle with water. The LIMES-concept has been demonstrated by quantitative measurements and manufacturing of small silicon photovoltaic modules. The project has significantly increased the potential for commercialization by increasing the TRL (Technology Readiness Level) level from 2-4 to 4-6. Investigations on how to scale up manufacturing flat glass in order to take the next step towards commercialization is on-going.

The current project was a collaborative project between the involved partners: RISE Glass, Lund University and Acoustic Agree. It is funded by ÅForsk (Grant No. 19-479). The project is a follow-up project from a Smart Housing Småland (Grant No. 2016-04218) pre-study where we used a nonlinear acoustic wave (NAW) to determine the damage value in float glass simultaneously with four-point bending tests. Glass is a brittle material whose strength is primarily determined by its surface characteristics i.e., the presence of flaws, defects or cracks on the surface. The strength of glass is greatly limited by stress-concentrations at the crack tips generating very high stresses when the glass is under load. The size and distribution of surface defects vary greatly, this gives a great variation of strength of glasses so that conventionally very large safety measures must be employed for glass products. If these defects and/or cracks could be detected in a non-destructive way, it would be beneficial for glass manufacturers as well as final building users. Nonlinear acoustic wave (NAW) techniques can be used to detect defects in materials. In these methods, acoustic waves are transmitted through an object and nonlinear effects, caused by the defects in the material, is analysed from the signal obtained at the receiver. The aim of the current project was to establish a calibration and a clear correlation between nonlinear acoustic wave measurements and the ultimate strength of annealed glass samples with controlled defects. Controlled defects were made as indentation imprints with a microindenter, equipped with a Vickers diamond head, in the middle of float glass samples with the dimensions 4×100×100 mm3. The applied loads were 0.5N, 1N, 2N, 5N and 10N. The indents were inspected with a microscope in order to see the cracks and the depth of the indents were also determined. The formed defects (cracks) were detected with NAW technique. Analysing the waves after propagating in the glass the nonlinear content in the wave was analysed. Due to the objects damage, the propagated wave distorts proportionally to the damage. After the NAW-inspection the strength of the glass samples were tested with ring-on-ring tests. Using the results from NAW-inspection, a clear correlation between the nonlinear response and the indenter load was found. There was also an obvious correlation between the failure load on the ring-on-ring-tests and the indenter load. The standard deviation for the ring-on-ring-tests for the 1N, 2N, 5N and 10 N was low but for the 0.5 N load was very high. A possible explanation is that the indenter imprint in most of the cases only gave rise to plastic deformation and in some samples, cracks were formed too. There were visible cracks for all the higher indenter loads and thus a lower scatter of the results. The main conclusion of the project is that it is possible to detect small cracks, which cannot be seen with the naked eye, with NAW technique and it can be directly correlated to the strength of the glass.

Titania is widely considered as an alternative constituent for replacing heavy metal oxides in optical glasses. Its effect on optical properties, however, is complex. This is due to the dielectric properties of the prevalent ionic species, Ti⁴⁺, the potential co-existence of trivalent titanium, Ti³⁺, giving rise to intrinsic and extrinsic charge transfer reactions, and the existence of different coordination polyhedra, depending on matrix composition. Here, we present a systematic study of the optical properties of the soda-lime-silicate glass system as a function of TiO₂ addition. We consider the silica-rich region of the SiO₂-Na₂O-CaO-TiO₂ quaternary, which may be taken as model for a variety of technical glasses. Trends are described in the refractive index, the Abbe number, the optical bandgap and the Urbach energy. The addition of TiO₂ increases the refractive index and the optical dispersion while it lowers the optical bandgap and the Urbach Energy. Results are discussed in relation to relevant literature data towards using titania silicate glasses as high-index replacements for heavy metal – containing oxide glasses.

The effect of single-side ion exchange (using a KNO3:KCl mixture) on the ring-on-ring flexural strength of float glass has been studied. Two ion exchanged series, treated at 450 and 515°C, were investigated. The ion exchanged samples showed approximately 160 respectively 100% increases in their arithmetic mean strength compared to as-received float glass. Furthermore, a series of samples containing drilled holes were studied in order to investigate the effect of singleside ion exchange on such common construction elements. The samples that contained drilled holes were ion exchanged at 450°C and showed around 140% increase of the fracture load compared to the untreated samples containing drilled holes. As a general observation, the ion exchange treatment induced ∼110 MPa compressive stresses (515°C) and ∼180 MPa compressive stresses (450°C). The ion exchanged samples showed no significant increase in stiffness.

In this paper, colouration of the tin side of commercial soda-lime-silica float glass by copper ion exchange is described and characterised. Data on the resulting concentration versus depth profiles, absorbance versus depth profiles, UV-Vis spectra and CIE-Lab colour coordinates are reported. Fundamental aspects of the process of colouration are described and discussed. Optimum saturation of the colour is achieved after ion exchange at 520°C for 10 h or at 500°C for 20 h. The depth of the coloured layer increases with increasing treatment time. At the same time, a linear dependency is found between the values of a and b in the CIE-Lab colour space for variations of treatment time and temperature. The later indicates broad tunability of colouration between different shades of ruby and varying colour saturation. It is shown that colour arises from a redox reaction between copper species and residual tin ions, and that the depth of the coloured layer is governed by the position of the tin hump. The critical concentration of tin and copper to achieve colour formation was found to be ∼0·25 mol% and >1 mol%, respectively.

The methods of chemical strengthening for improving the mechanical properties of oxide glasses are reviewed. Chemical strengthening is compared with thermal strengthening and different methods of measuring strength are discussed. Different ions, salts and other related methods for improving the ion exchange process and mechanical properties are described as well as applications of strengthening.

The surface ablation cell (SAC), a laboratory equipment for determining surface concentration profiles, has been utilised to characterise surface ion exchange processes in float glass. In this paper, single-side ion exchange is reported. Data on the ion concentration profiles were used to calculate diffusion coefficients as well as the activation energy for K +-Na+ ion exchange. The air-sides of float glass samples were treated with two different salt mixtures, (I) 2:1 KNO3:KCI, and (II) 1:2 KNO3:KCl, (both by weight), and heated to different temperatures below Tg, 460-520°C. The diffusion coefficients calculated using a Green's function approach were in the ranges (I) 1.4×10-11 to 6.8×10-11 and (II) 1.8×10-11 to 6.0×10-11 cm2/s while those calculated using Boltzmann-Matano were in the ranges (I) 5.7×10 -11 to 14×10-12 and (II) 3.4×10-12 to 6.0×10-12 cm2/s. Average values of the activation energies obtained through the Green's function were (I) 111.0 kJ/mol and (II) 99.8 kJ/mol for the different salt mixtures.

För att slippa vänta på plusgrader håller en samling forskare på RISE på attutveckla och testa nya ytbeläggningar för solceller som ska göra att snö och isinte fäster på dem. Snö och is kan leda till stopp i elproduktionen - en solcellsmodulsom är täckt av snö och is generar i praktiken ingen elektricitet eftersomsolljuset inte tränger igenom i tillräcklig omfattning. Dessutom kan rejälasnömängder leda till stora belastningar på underliggande konstruktioner.

I ett nyligen avslutat forskningsprojekt har Absolicon Solar Collector tillsammans med RISE Research Institutes of Sweden och Umeå universitet utvecklat en ny toppmodern antireflektiv beläggning som kan göra Absolicons solfångare än mer effektiva. Nu siktar man på ett nytt projekt för att skala upp metoden.

Ett förekommande problem under byggprocessen är betongrinning. Innebörden av betongrinning är att vatten varit i kontakt med färsk betong och därefter påverkat glasytor till fasader/balkonger/fönster. Påverkan på glaset kan vara fysisk och ibland även kemisk. Resultatet blir droppfläckar, rinnmärken och utfällningar som försämrar glasets ljusgenomsläpplighet och estetiska intryck. Så länge påverkan enbart är fysisk är denna skada relativt lätt att ta bort antingen med hjälp av mekanisk polering eller genom att torka glaset med utspädd syra. Ofta fortskrider dock processen till ett kemiskt angrepp på glaset, vilket är permanent och inte går att avlägsna helt med ovan nämnda metoder. Kemiska reaktioner har då skapat etsningar i glasytan som på sikt blir i storleksordningen mikrometer djupa.

I denna förstudie har vi försökt simulera betongrinningsangrepp dels under kontrollerade förhållanden i laboratoriemiljö och dels i utomhusmiljö. Försöksvariablerna var två olika betongvarianter samt glas med respektive utan ett på marknaden befintligt glasskyddande medel. Resultatet av försöken har analyserats genom okulär bedömning, mikroanalys med svepelektronmikroskop och energidispersiv röntgenspektroskopi samt yttopografimätningar med optisk profilometer. Testerna resulterade i utfällningar på glasytan innehållande ämnena svavel, kalium och kalcium, vilka bedöms härstamma från betongen. Efter inomhusförsöken, som pågick i fyra månader, gick utfällningarna att tvätta bort med saltsyralösning, och inga djupgående, permanenta korrosionsskador syntes på glaset. Utomhusförsöken utsträcktes till elva månader, varpå bestående skador kunde konstateras på glasytorna efter att utfällningarna tvättats bort. Djupet på skadorna uppmättes som mest till cirka en halv mikrometer. Varken sänkning av pH i betongen eller skyddsbehandling av glaset bidrog till att hindra uppkomst av fläckighet eller etsningar på glaset. I diskussioner med industrirepresentanter konstaterades att betongrinning är ett ganska vanligt problem, som är oberoende av geografi. Tidigare försök med behandling av både betong och glas varit verkningslösa. I majoriteten av fall handlar problemen om inglasade balkonger alternativt glasräcken i kombination med balkongplatta i betong. Det man vet fungerar är att använda en korrekt konstruktion som hindrar vattnet från att droppa ned på glaset. Regelbunden rengöring av glasen hjälper också och kommer förmodligen hamna som ett underhållskrav mot kunder.