Structural dependence of threshold displacement energies in rutile, anatase and brookite TiO2
MetadataShow full item record
This is the author’s version of a work that was accepted for publication in Materials Chemistry and Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Chemistry and Physics, Volume 147, Issues 1–2, 15 September 2014, Pages 311–318. http://doi.org/10.1016/j.matchemphys.2014.05.006
Systematic molecular dynamics simulations of low energy cascades have been performed to examine how threshold displacement events are affected by changes in crystal structure. Exploiting the structural proximity of the rutile, anatase and brookite polymorphs of TiO2, a quantitative examination of defect production has been carried out including detailed defect analysis and the determination of values of the threshold displacement energy (Ed). Across all polymorphs comparable values of Ed are reported for oxygen at around 20 eV, with the value for Ti in rutile (73 ± 2 eV) significantly higher than that in brookite (34 ± 1 eV) and anatase (39 ± 1 eV). Quantifying defect formation probability as a function of Primary Knock-on Atom (PKA) energy, simulations in rutile indicate a consistent reduction in defect formation at energies higher than Ed relative to anatase and brookite. Defect cluster analysis reveals a significant proportion of di-Frenkel pairs in anatase at Ti PKA energies around Ed. These clusters, which are stabilised by the localisation of two Frenkel pairs, are associated with a recombination barrier of approximately 0.19 eV. As such, annihilation is likely under typical a experimental condition which suggests an expected increase in the measured Ti value of Ed. Identical O defect populations produced at the threshold by the O PKA in both rutile and anatase explain the comparable values of Ed. At higher O PKA energies, the commencement of defect production on both sublattices in anatase is observed in contrast to the confinement of defects to the O sublattice in rutile. The overall trends reported are consistent with in-situ irradiation experiments and thermal spike simulations, suggesting the contrasting radiation response of the polymorphs of TiO2 is apparent during the initial stages of defect production.
Showing items related by title, author, creator and subject.
Akindeju, Michael Kehinde (2013)Considering the level of current interests in the continuous synthesis of Titania, the Chemical and Manufacturing Industry is expected to benefit from the results of this work which proposed and implemented a tailor-made ...
Microstructural, trace element and geochronological characterization of TiO2 polymorphs and implications for mineral explorationPlavsa, D.; Reddy, Steven; Agangi, Andrea; Clark, Christopher; Kylander-Clark, A.; Tiddy, C. (2018)The geochemistry of rutile (TiO 2 ) has recently found its use in mineral exploration with some studies reporting anomalous concentrations of Fe, W, V, Sn and Sb in rutile associated with mineralized ore systems. However, ...
Qin, M.; Kuo, E.; Whittle, K.; Middleburgh, S.; Robinson, Marc; Marks, Nigel; Lumpkin, G. (2013)The radiation response of TiO2 has been studied using molecular dynamics. The simulations are motivated by experimental observations that the three low-pressure polymorphs, rutile, brookite and anatase, exhibit vastly ...