Grain Boundary Segregation of Single Dopants (Y, La, Mg)

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.

 

 
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)