Atomistic simulations of displacement cascades in Y2O3 single crystal

• Published in: Journal of nuclear materials Vol. 454; no. 1-3; pp. 96 - 104
• Main Authors: Dholakia, Manan, Chandra, Sharat, Valsakumar, M.C., Mathi Jaya, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2014
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2014.07.044

(a) The averaged distortion index and the Y–O bond length of the Y2O3 octahedra as a function of the simulation time for 5keV PKA. (b) Shows the nearest neighbourhood of one of the Y ions as a function of simulation time, showing the destruction and the recovery of the YO6 octahedron during the cascade corresponding to 5keV Y PKA. [Display omitted] •Qualitative difference in displacement cascades exists for Y and O PKA.•Nearest neighbour correlation between Y and O ions exists even at cascade peak.•Cascade core in Y2O3 does not undergo melting.•Topological connectivity of YO6 polyhedra plays important role in stability of Y2O3. We study the characteristics of displacement cascades in single crystal Y2O3 using classical molecular dynamics. There are two possible ways to generate the cascades in yttria, using either the Y or the O atoms as the primary knock-on (PKA) atom. It is shown that there is a qualitative difference in the characteristics of the cascades obtained in these two cases. Even though the crystal is seen to be in a highly disordered state in the cascade volume, as seen from the plots of radial distribution function, the correlation between the Y and O atoms is not completely lost. This facilitates a quick recovery of the system during the annealing phase. Topological connectivity of the YO6 polyhedral units plays an important role in imparting stability to the Y2O3 crystal. These characteristics of the cascades can help explain the stability of the yttria nanoparticles when they are dispersed in oxide dispersion strengthened steels.