The displacement energies of cations in perovskite (CaTiO 3 ) Katherine L. Smith a, * , Nestor J. Zaluzec b a Materials and Engineering Science, Australian Nuclear Science and Technology Organisation, P.M.B. 1, Menai, NSW 2234, Australia b Materials Science Division, Argonne National Laboratory, 9700 North Cass Ave, Argonne, IL 60439, USA Received 8 June 2004; accepted 29 September 2004 Abstract High angular resolution electron channelling X-ray spectroscopy (HARECXS) was used to monitor the intensity ratio of CaKa/TiKa X-rays emitted by perovskite (CaTiO 3 ) as a function of incident electron beam orientation. The collected HARECXS data suggest that the displacement energies of calcium and titanium in perovskite (CaTiO 3 ) are 82 ± 11eV and 69 ± 9eV, respectively. These values are approximately 40% larger than those currently used to con- vert ion doses applied to oxides into dpa using SRIM. Ó 2004 Elsevier B.V. All rights reserved. PACS: 61.82.Fk; 61.85.+p 1. Introduction Radiation damage can affect the chemical durability of phases and/or assemblages (waste forms) designed to host high level radioactive waste (HLW) [1]. As HLW waste forms are designed to hold actinides for geologic periods of time (10 4 –10 6 years), it is desirable to be able to predict and/or model the occurrence of radiation damage induced defects over long time peri- ods. Data to aid the development of models can be col- lected from (a) natural analogue minerals or from (b) experiments where waste forms are doped with short- lived actinides or irradiated with high-energy heavy ions or fast neutrons [2]. To compare data from these exper- iments, it is necessary to convert the various disparate dose units into the standard unit of displacements per atom (dpa). Knowledge of the displacement energies (E d values) of the ions in the actinide host phases is essential for these calculations. High angular resolution electron channelling X-ray spectroscopy (HARECXS) is a transmission electron microscope (TEM) based technique which exploits elec- tron channelling phenomena [3–10]. It was originally developed to determine crystallographic site occupancies in fully crystalline matrices but has been used to monitor the onset of radiation damage induced cation mixing in spinel [11]. HARECXS measurements involve rocking the incident electron beam under computer control along specific crystallographic axes and simultaneously monitoring the resulting characteristic X-ray emission signal as a function of orientation of the beam to the crystal. The relative intensities of characteristic peaks change as a function of channelling along crystallo- graphic directions and alter in response to local compo- sition and/or changes in the perfection of the crystal. This phenomenon is particularly useful when applied to directions in the crystalline lattices which present 0022-3115/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jnucmat.2004.09.021 * Corresponding author. Tel.: +61 (0)2 9717 3505; fax: +61 (0)2 9543 7179. E-mail address: kls@ansto.gov.au (K.L. Smith). Journal of Nuclear Materials 336 (2005) 261–266 www.elsevier.com/locate/jnucmat