Silver-enhanced nucleation and morphology control of surface crystallized Ba0.5Sr0.5Zn2Si2O7 from 8 BaO·8 SrO·34 ZnO·50 SiO2 glass
| Autor: | Katrin Thieme, Christian Rüssel, Michael Kracker, Thomas Höche, Christian Thieme |
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| Přispěvatelé: | Publica |
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Surface (mathematics) Materials science Process Chemistry and Technology Nucleation 02 engineering and technology Thermal treatment 021001 nanoscience & nanotechnology 01 natural sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Metal Negative thermal expansion Phase (matter) visual_art 0103 physical sciences Materials Chemistry Ceramics and Composites Perpendicular visual_art.visual_art_medium Composite material 0210 nano-technology Layer (electronics) |
| Zdroj: | Ceramics International. 45:18760-18766 |
| ISSN: | 0272-8842 |
| DOI: | 10.1016/j.ceramint.2019.06.102 |
| Popis: | Glass samples were polished and coated with a 10 nm thick silver layer. Both, silver-coated and uncoated samples were thermally treated at 750 °C for 4 h or at 790 °C for 2 h. In both types of samples, the phase Ba0.5Sr0.5Zn2Si2O7 crystallized, which exhibits a negative thermal expansion. After thermal treatment, the uncoated sample showed a low number of crystals at the surface and even less if a crystallization temperature of 790 °C was supplied. By contrast, the silver-coated sample exhibited much more crystals at the surface. The number of crystals did not considerably depend on the crystallization temperature. The crystals in the silver-coated sample grew into the bulk with a highly unique orientation. Their crystallographic c-axes are perpendicular to the surface. The orientation of the crystals of the uncoated sample was not as strict. The uncoated sample showed numerous cracks, while the silver-coated sample did not show any cracks. In a first step, the metallic silver layer is dewetted and forms a structure composed by silver islands. During further heating, the islands are oxidized to Ag2O, which diffuses in the glass. Since Ag2O is incorporated in the glass as a network modifier, the network connectivity of the glass and hence also Tg decreases. This results in a higher nucleation rate in surface near regions. |
| Databáze: | OpenAIRE |
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