Journal of Sol-Gel Science and Technology

, Volume 75, Issue 3, pp 602–616 | Cite as

Microstructure and transmittance of silica gels for application as transparent heat insulation materials

  • Friederike Klenert
  • Jens Fruhstorfer
  • Christos G. Aneziris
  • Ulrich Gross
  • Dimosthenis Trimis
  • Iris Reichenbach
  • Dig Vijay
  • Anja Horn
Original Paper


Transparent heat insulation materials (TIMs) exhibit great potential for different solar applications. Despite this fact, they are not used widely, since they are either very expensive (aerogel) or made from organic materials and, thus, are not resistant to higher temperatures. Xerogel, obtained from silica gel by drying at ambient pressure, is a promising material for the production of TIMs. This study investigates different treatments applied during the production of silica gel and their influence on its optical and structural properties. To this end, silica sol was gelled and the resulting silica gel was aged before it was either hydrothermally treated or fired. Subsequently, radiation transmission measurements from 400 to 2700 nm as well as porosity, specific surface area, and scanning electron microscopic/transmissions electron microscopic measurements were conducted. It was found that under certain conditions, the transmittance can be improved by firing as well as by hydrothermal treatment. Firing at 600 °C with 10-min dwell time and hydrothermal treatment at 120 °C with 5-h dwell time resulted in the silica gels with the highest transmittance of 63 up to 66 %. The porosity (24–76 %), the pore radii (3–26 nm), and the specific light absorption by embedded water and SiOH molecules could be adjusted over a wide range.

Graphical abstract


Silica gels Xerogels Transparent heat insulation materials Transmittance Porosity Hydrothermal treatment Firing treatment 



The authors are grateful to Dr. G. Schmidt from the Institute of Ceramic, Glass and Construction Materials for conducting scanning electron microscopy measurements as well as to Dr. V. Klemm from the Institute of Material Science, for the transmission electron microscopy measurements, both at TU Bergakademie Freiberg. Furthermore, Dr. R. Dittrich from the Institute Electronic and Sensor Materials is gratefully acknowledged for conducting the nitrogen adsorption and desorption measurements, also from TU Bergakademie Freiberg. The authors would like to gratefully acknowledge the financial support of the European Commission through the European Social Fund (ESF) and the Saxon State Ministry of Science and the Arts for the project ANWan (No. SAB 100109651).


  1. 1.
    Stieglitz R, Heinzel V (2012) Thermische Solarenergie: Grundlagen, Technologie, Anwendung. Springer, Berlin, HeidelbergCrossRefGoogle Scholar
  2. 2.
    Reiter C, Trinkl C, Zörner W (2011) Solarthermie 2000plus: Kunststoffe in solarthermischen Kollektoren- Anforderungsdefinition. Konzeptentwicklung und Machbarkeitsbewertung, IngolstadtGoogle Scholar
  3. 3.
    Voss K (1997) Transparente Wärmedämmung: Stand der Technik. Sonnenenergie und Wärmetechnik 1:18–21Google Scholar
  4. 4.
    Fachverband Transparente Wärmedämmung e.V. (2000) Transparente Wärmedämmung: Eigenschaften und Funktionen, GundelfingenGoogle Scholar
  5. 5.
    Klein G (2008) Energieeffizient bauen. Innovationen mit Kunststoff. Kunststoffe 12:80–84Google Scholar
  6. 6.
    Wei G, Liu Y, Zhang X et al (2011) Thermal conductivies study on silica aerogel and its composite insulation materials. Int J Heat Mass Transf 54:2355–2366CrossRefGoogle Scholar
  7. 7.
    Steiner S (2014) Silica aerogel. Accessed 17 Jun 2014
  8. 8.
    Reichenauer G, Noisser T, Ebert HP, Weigang L (2009) Poröses SiO2 Xerogel mit charakteristischer Porengröße, dessen trocknungsstabile Vorstufen und dessen Anwendungen (DE10 2009 053782A1)Google Scholar
  9. 9.
    Pilz A (2012) Innovativ dämmen mit Aerogel. Applica 9:14–21Google Scholar
  10. 10.
    Lee JK, Gould GL (2007) Polydicyclopentadiene based aerogel—a new insulation material. J Sol-Gel Sci Technol 44:29–40CrossRefGoogle Scholar
  11. 11.
    Hauer A (2002) Beurteilung fester Adsorbentien in offenen Sorptionssystemen für energetische Anwendungen. Technische Universität Berlin, BerlinGoogle Scholar
  12. 12.
    Titulaer MK, den Exter MJ, Talsma H et al (1994) Control of the porous structure of silica gel by the preparation pH and drying. J Non-Cryst Solids 170:113–127CrossRefGoogle Scholar
  13. 13.
    Christy AA (2011) Effect of hydrothermal treatment on adsorption properties of silica gel. Ind Eng Chem Res 50:5543–5549CrossRefGoogle Scholar
  14. 14.
    Titulaer MK, Jansen J, Geus JW Fluid composition effects on silica gel aging. J Non-Cryst Solids 170:11–20Google Scholar
  15. 15.
    Schmitz JO (2000) Zum Einfluss der hydrothermalen Alterung auf die Sorptionseigenschaften von Trägergelen für die heterogene Katalyse. Dissertation, Gerhard Mercator Universität DuisburgGoogle Scholar
  16. 16.
    Tschritter H, Daßler B, Knölle G, Herbst A, Wiesner R (2006) Verfahren zur Herstellung von hochreinem Silicagel (DE102006022685A1)Google Scholar
  17. 17.
    Iler RK (1979) The chemistry of silica. solubility, polymerization, colloid and surface properties and biochemistry. Wiley, CanadaGoogle Scholar
  18. 18.
    Schießl C (2008) Thermische Analyse- Möglichkeiten zur Untersuchung von dentalen Kunststoffen. Dissertation, Universität RegensburgGoogle Scholar
  19. 19.
    Shi F, Wang L, Liu J et al (2007) Effect of heat treatment on silica aerogels prepared via ambient drying. J Mater Sci Technol 23(3):402–406Google Scholar
  20. 20.
    Davis PJ, Deshpande R, Smith DM et al (1994) Pore structure evolution in silica gel during aging/drying. IV. Varying pore fluid pH. J Non-Cryst Solids 167(3):295–306. doi: 10.1016/0022-3093(94)90252-6 CrossRefGoogle Scholar
  21. 21.
    Brinker CJ, Mukherjee SP (1981) Conversion of monolithic gels to glasses in a multicomponent silicate glass system. J Mater Sci 16:1980–1988CrossRefGoogle Scholar
  22. 22.
    Fournier RO, Rowe JJ (1977) The solubility of amorphous silica in water at high temperatures and high pressures. Am Miner 62:1052–1056Google Scholar
  23. 23.
    Brinker CJ, Scherer GW (1990) Sol–gel science. The physics and chemistry of sol–gel processing. Academic Press, New YorkGoogle Scholar
  24. 24.
    Pramanik A, Bhattacharjee K, Mitra MK et al (2013) A mechanistic study of the initial stage of the sintering of sol–gel derived silica nanoparticles. Int J Mod Eng Res 3(2):1066–1070Google Scholar
  25. 25.
    Brinker C, Roth E, Scherer G et al (1985) Structural evolution during the gel to glass conversion. J Non-Cryst Solids 71(1–3):171–185. doi: 10.1016/0022-3093(85)90286-8 CrossRefGoogle Scholar
  26. 26.
    Kondo S, Tomoi K, Pak C (1979) The characterization of the hydroxyl surface of silica gel. Bull Chem Soc Jpn 52(7):2046–2050CrossRefGoogle Scholar
  27. 27.
    Zarzycki J, Prassas M, Phalippou J (1982) Synthesis of glasses from gels: the problem of monolithic gels. J Mater Sci 17:3371–3379CrossRefGoogle Scholar
  28. 28.
    Modest MF (2003) Radiative heat transfer, 2nd edn. Academic PressGoogle Scholar
  29. 29.
    Krol DM, van Lierop JG (1984) The densification of monolithic gels. J Non-Cryst Solids 63(1–2):131–144. doi: 10.1016/0022-3093(84)90392-2 CrossRefGoogle Scholar
  30. 30.
    Scherer GW, Calas S, Sempéré R (1998) Densification kinetics and structural evolution during sintering of silica aerogel. J Non-Cryst Solids 240(1–3):118–130. doi: 10.1016/S0022-3093(98)00696-6 CrossRefGoogle Scholar
  31. 31.
    Yoldas BE (1993) Technological significance of sol–gel process and process-induced variations in sol–gel materials and coatings. J Sol-Gel Sci Technol 1:65–77CrossRefGoogle Scholar
  32. 32.
    Davis PJ, Brinker C, Smith DM (1992) Pore structure evolution in silica gel during aging/drying I. Temporal and thermal aging. J Non-Cryst Solids 142:189–196. doi: 10.1016/S0022-3093(05)80025-0 CrossRefGoogle Scholar
  33. 33.
    Kondo S, Fujiwara F, Muroya M (1976) The effect of heat-treatment of silica gel at high temperature. J Colloid Interface Sci 55(2):421–430. doi: 10.1016/0021-9797(76)90052-7 CrossRefGoogle Scholar
  34. 34.
    Ohmacht R, Matus Z (1984) Hydrothermal treatment of silica gel. Chromatographia 19:473–476CrossRefGoogle Scholar
  35. 35.
    Leboda R, Mendyk E, Tertykh VA (1995) Effect of the hydrothermal treatment method in an autoclave on the silica gel porous structure. Mater Chem Phys 42(1):7–11. doi: 10.1016/0254-0584(95)01561-2 CrossRefGoogle Scholar
  36. 36.
    Montgomery DC (2001) Design and analysis of experiments. Wiley, New YorkGoogle Scholar
  37. 37.
    Aines RD, Kirby SH, Rossman GR (1984) Hydrogen speciation in synthetic quartz. Phys Chem Miner 11:204–212CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Friederike Klenert
    • 1
  • Jens Fruhstorfer
    • 1
  • Christos G. Aneziris
    • 1
  • Ulrich Gross
    • 2
  • Dimosthenis Trimis
    • 2
  • Iris Reichenbach
    • 2
  • Dig Vijay
    • 2
  • Anja Horn
    • 2
  1. 1.Institute of Ceramic, Glass and Construction MaterialsTU Bergakademie FreibergFreibergGermany
  2. 2.Institute of Thermal EngineeringTU Bergakademie FreibergFreibergGermany

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