Effect of and the ratio on high-temperature stability of materialsJ. Houska1, J. Vlcek1, S. Hreben1, M. M. M. Bilek2 and D. R. McKenzie2
1 Department of Physics, University of West Bohemia - Univerzitni 22 30614 Plzen, Czech Republic
2 School of Physics, The University of Sydney - Sydney, NSW 2006, Australia
received 3 July 2006; accepted 8 September 2006
published online 7 October 2006
Amorphous Si-B-C-N alloys were deposited by reactive magnetron sputtering, and their high-temperature stability was investigated using a combined approach of experiment and molecular-dynamics simulations. We show that both a higher Si/C ratio and the addition of boron improve the thermal stability of the materials. We find that lifetimes of bonds of the same type are significantly longer at the higher Si/C ratio. The addition of boron results in a conversion of some of the electrons in lone pairs associated with nitrogen to bonding electrons. This increases the network's average coordination number. In both cases, the higher network coordination number and resulting lower diffusion, expressed in terms of longer bond lifetimes, shift decomposition reactions in materials to higher temperatures.
81.05.Zx - New materials: theory, design, and fabrication.
68.60.Dv - Thermal stability; thermal effects.
81.05.Je - Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides).
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