Glass - Back to the Future!

Presenting Author:
Ferdinand Drünert

article posted 22 March 2016

Ferdinand Drünert graduated in chemistry in 2013. Since the start of his PhD project he is focussing on the spectroscopic analysis of historical glass samples, as well as comparison with modern, remade glass samples.

Characterization of Various Copper Microcrystals in Different Glasses - A Multi-Method Approach

Ferdinand Drünert(a)*, Magdalena Blanz(a), Stefanie Reiß,(b) Doris Möncke(a) & Lothar Wondraczek(a)
Otto Schott Institute of Materials Research, Friedrich Schiller University, Fraunhoferstraße 6, 07743 Jena, Germany (a) Otto Schott Institute of Materials Research, Friedrich Schiller University, Fraunhoferstraße 6, D-07743 Jena, Germany (b) Institute of Physics and Institute of Micro- and Nanotechnologies, TU Ilmenau, P.O. Box 100565, D-98684

Glasses with high copper concentrations do usually not have a pure amorphous glass phase: At elevated concentrations, or when melting under reducing conditions, a precipitation of crystalline structures can be observed, usually in form of cupric (CuO) or cuprous (Cu2O) oxide or even of metallic copper particles.
In the current study, the goal was to differentiate between the different Cu-containing crystals by infrared (IR) or Raman spectroscopy. Therefore, it was also necessary to identify crystallites by X-ray diffraction (XRD), their morphology by optical and electron microscopy, and the Cu-valence by photoelectron spectroscopy (XPS).
The glasses studied belong to ZnO–CuO–B2O3, PbO–CuO–B2O3, fluoride-phosphate and aluminosilicate glass systems. It could be shown, that high amounts of cupper-oxide in the glass lead to the precipitation of Cu0, Cu2O and/or CuO crystals. Using Cu(NO3)2 as raw material reduces the fraction of lower valence Cu-ions and enhances the formation of an amorphous glass phase.

Figure 1: CuO–B2O3 glass sample. The black exterieur is coloured by Cu2+ ions in the glass matrix and include only few CuO crystals, whereas the colour inside is caused by Cu2O crystals

Figure 2: Aluminosilicate glass sample. The bulk shows a brown-yellow colour caused by Cu2O crystallites