To better understand dopant segregation and its influence on grain boundary structures and properties, the segregation of Y, Mg and La dopants to α-alumina mirror twin grain boundaries was simulated using classical energy minimisation [1, 2]. To make a link to experimental observations (e.g. grain size) a new Monte Carlo based method in conjunction with a microstructural model [link to YAG page?] has been developed to calculate the nominal solubility of the dopants as a function of the grain size [3]. The result show very satisfactory correspondence with experimental data – allowing atomistic scale interpretation of macroscopic ceramic behaviour – important for transport and optical properties.
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| Structure of a simulated Σ7(01.2) α-alumina grain boundary containing Mg dopants (green)[2]. | Atomistic based theoretical (lines) and experimental (points) for the solubility limit of Mg in α-alumina as a function of the grain size [2]. |
Publications
[1] Galmarini S., Aschauer U., Bowen P., Parker S.C., Atomistic Simulation of Y-Doped α-Alumina Interfaces, Journal of the American Ceramic Society, 91(11), (2008), 3643-51, (Link to article)
[2] Galmarini S., Aschauer U., Tewari A., Aman Y., Van Gestel C., Bowen P., Atomistic modeling of dopant segregation in α-alumina ceramics: Coverage dependent energy of segregation and nominal dopant solubility. Journal of the European Ceramic Society (2011),31:2839–52 (Link to article)
[3] Tewari A., Galmarini S., Stuer M., Bowen P., Atomistic modeling of the effect of codoping on the atomistic structure of interfaces in α-alumina. Journal of the European Ceramic Society (2012),32:2935–48 (Link to article)
[4] A. Tewari, F. Nabiei, S. C. Parker, M. Cantoni, M. Stuer, P. Bowen, C. Hébert Towards Knowledge Based Grain Boundary Engineering of Transparent Polycrystalline Alumina Combining Advanced TEM and Atomistic Modeling” J. Am. Ceram. Soc., in press (2015) DOI: 10.1111/jace.13552
[5] Aschauer U., Bowen P., Parker S.C., Oxygen vacancy diffusion in alumina: New atomistic simulation methods applied to an old problem, Acta Materialia, 57(16), (2009), 4765-72, (Link to article)
[6] A. Tewari, U. Aschauer, P. Bowen, “Atomistic Modeling of Effect of Mg on Oxygen Vacancy Diffusion in [alpha]-Alumina” J.Amer.Ceram.Soc., 97(8) 2596-2601 (2014)