Abstract
Oxynitride glasses are derivatives of oxide glasses, where nitrogen is partially substituted for oxygen. Glasses in the Ln-SiAlON systems are important because they appear in SiAlON ceramics as grain boundary phases. In contrast to the other lanthanides, Eu-containing glasses present specific properties. The oxidation state of europium plays an important role in the construction of the glass network and the resulting phases in the glass-ceramic. Eu-SiAlO glasses with the composition in atomic percentage 11.8%Eu:17.8%Si:6.8%Al:63.6%O, have been prepared under air and under nitrogen to reveal the influence of the atmosphere on the oxidation state of the Eu-ion. Properties such as glass transition temperature (Tg), thermal expansion coefficient, density and Young's modulus have been assessed for the glass. The glass prepared under the nitrogen atmosphere presents a very low Tg (679°C) compared to the glass prepared under air (844°C). In addition, lower values of the mechanical properties were found for the glass prepared under nitrogen. In order to reveal the real oxidation state of the Eu-ion in each glass, crystallisation studies were conducted on the glasses under air and under nitrogen, respectively, at temperatures ranging from 1050 to 1200°C. X-ray diffraction and scanning electron microscopy were conducted to reveal the crystalline phases and the microstructure. All results for the oxide glass were compared with an oxynitride glass with the same cation composition. The glasses prepared under nitrogen atmosphere possess Eu in the +11 oxidation state.
Original language | English (Ireland) |
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Pages (from-to) | 277-282 |
Number of pages | 6 |
Journal | Materials Science Forum |
Volume | 325-326 |
Publication status | Published - 2000 |
Event | Proceedings of the 1998 2nd International Symposium on Nitrides - Limerick, Ireland Duration: 9 Jun 1998 → 11 Jun 1998 |
Keywords
- Crystalline phases
- Crystallisation
- Europium
- Eusiaion
- Oxidation state
- Oxynitride glass