This work has shown that the field of oxynitride glass ceramics is larger than originally thought, and that many new phases exist which merit further exploration. Whereas the properties of the materials explored in the present programme are at least comparable with current oxide glass ceramics, the present results show that further development of the newer glass ceramics studied in this programme may be beneficial.
Novel glasses and glass-ceramics are under development for devices for use in opto-electronic, biomedical/chemical and thermal/mechanical applications in a wide range of high technology industries. The ease of shaping glasses and the possibility of controlling the crystallisation to produce glass-ceramics containing more refractory crystalline phases with low coefficients of thermal expansion offer significant advantages for fabrication. In addition, the occurrence of oxynitride glasses as grain boundary phases in silicon nitride based ceramics merits their further study ad materials in their own right and as the basis for production of oxynitride glass-ceramics. This proposal combines expertise in three member states to carry out the following objectives :
1. Study of the formation and characteristics of oxynitride glasses (in M-Si-Al-O-N systems where M is Y or R.E.).
2. Study of the effect of N and the rare earth cations on properties.
3. Characterisation of the structure of the glasses using NMR,Raman scattering, XRD, EXAFS, and Neutron Diffraction.
4. Optimisation of the nucleation and crystallisation of these glasses in order to develop glass-ceramics with tailored properties and beneficial microstructures.
5. Use of the Knowledge acquired to optimise grain-boundary phases in nitrogen ceramics.
Funding SchemeCSC - Cost-sharing contracts
NE1 7RU Newcastle Upon Tyne